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| author | antirez <antirez@gmail.com> | 2009-03-22 10:30:00 +0100 |
|---|---|---|
| committer | antirez <antirez@gmail.com> | 2009-03-22 10:30:00 +0100 |
| commit | ed9b544e10b84cd43348ddfab7068b610a5df1f7 (patch) | |
| tree | 1a5e9ace4bf21ad1a754907b703debe5b3e87842 /doc | |
| download | redis-ed9b544e10b84cd43348ddfab7068b610a5df1f7.tar.gz | |
first commit
Diffstat (limited to 'doc')
52 files changed, 2552 insertions, 0 deletions
diff --git a/doc/Benchmarks.html b/doc/Benchmarks.html new file mode 100644 index 000000000..e33e7b71a --- /dev/null +++ b/doc/Benchmarks.html @@ -0,0 +1,121 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>Benchmarks: Contents</b><br> <a href="#How Fast is Redis?">How Fast is Redis?</a><br> <a href="#Latency percentiles">Latency percentiles</a> + </div> + + <h1 class="wikiname">Benchmarks</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="How Fast is Redis?">How Fast is Redis?</a></h1>Redis includes the <code name="code" class="python">redis-benchmark</code> utility that simulates SETs/GETs done by N clients at the same time sending M total queries (it is similar to the Apache's <code name="code" class="python">ab</code> utility). Below you'll find the full output of the benchmark executed against a Linux box.<br/><br/><ul><li> The test was done with 50 simultaneous clients performing 100000 requests.</li><li> The value SET and GET is a 256 bytes string.</li><li> The Linux box is running <b>Linux 2.6</b>, it's <b>Xeon X3320 2.5Ghz</b>.</li><li> Text executed using the loopback interface (127.0.0.1).</li></ul> +Results: <b>about 110000 SETs per second, about 81000 GETs per second.</b><h1><a name="Latency percentiles">Latency percentiles</a></h1><pre class="codeblock python" name="code"> +./redis-benchmark -n 100000 + +====== SET ====== + 100007 requests completed in 0.88 seconds + 50 parallel clients + 3 bytes payload + keep alive: 1 + +58.50% <= 0 milliseconds +99.17% <= 1 milliseconds +99.58% <= 2 milliseconds +99.85% <= 3 milliseconds +99.90% <= 6 milliseconds +100.00% <= 9 milliseconds +114293.71 requests per second + +====== GET ====== + 100000 requests completed in 1.23 seconds + 50 parallel clients + 3 bytes payload + keep alive: 1 + +43.12% <= 0 milliseconds +96.82% <= 1 milliseconds +98.62% <= 2 milliseconds +100.00% <= 3 milliseconds +81234.77 requests per second + +====== INCR ====== + 100018 requests completed in 1.46 seconds + 50 parallel clients + 3 bytes payload + keep alive: 1 + +32.32% <= 0 milliseconds +96.67% <= 1 milliseconds +99.14% <= 2 milliseconds +99.83% <= 3 milliseconds +99.88% <= 4 milliseconds +99.89% <= 5 milliseconds +99.96% <= 9 milliseconds +100.00% <= 18 milliseconds +68458.59 requests per second + +====== LPUSH ====== + 100004 requests completed in 1.14 seconds + 50 parallel clients + 3 bytes payload + keep alive: 1 + +62.27% <= 0 milliseconds +99.74% <= 1 milliseconds +99.85% <= 2 milliseconds +99.86% <= 3 milliseconds +99.89% <= 5 milliseconds +99.93% <= 7 milliseconds +99.96% <= 9 milliseconds +100.00% <= 22 milliseconds +100.00% <= 208 milliseconds +88109.25 requests per second + +====== LPOP ====== + 100001 requests completed in 1.39 seconds + 50 parallel clients + 3 bytes payload + keep alive: 1 + +54.83% <= 0 milliseconds +97.34% <= 1 milliseconds +99.95% <= 2 milliseconds +99.96% <= 3 milliseconds +99.96% <= 4 milliseconds +100.00% <= 9 milliseconds +100.00% <= 208 milliseconds +71994.96 requests per second +</pre>Notes: changing the payload from 256 to 1024 or 4096 bytes does not change the numbers significantly (but reply packets are glued together up to 1024 bytes so GETs may be slower with big payloads). The same for the number of clients, from 50 to 256 clients I got the same numbers. With only 10 clients it starts to get a bit slower.<br/><br/>You can expect different results from different boxes. For example a low profile box like <b>Intel core duo T5500 clocked at 1.66Ghz running Linux 2.6</b> will output the following: +<pre class="codeblock python python" name="code"> + ./redis-benchmark -q -n 100000 +SET: 53684.38 requests per second +GET: 45497.73 requests per second +INCR: 39370.47 requests per second +LPUSH: 34803.41 requests per second +LPOP: 37367.20 requests per second +</pre> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/BgsaveCommand.html b/doc/BgsaveCommand.html new file mode 100644 index 000000000..5fab9485e --- /dev/null +++ b/doc/BgsaveCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>BgsaveCommand: Contents</b><br> <a href="#BGSAVE">BGSAVE</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">BgsaveCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="BGSAVE">BGSAVE</a></h1> +<blockquote>Save the DB in background. The OK code is immediately returned.Redis forks, the parent continues to server the clients, the childsaves the DB on disk then exit. A client my be able to check if theoperation succeeded using the <a href="LastsaveCommand.html">LASTSAVE</a> command.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SaveCommand.html">SAVE</a></li><li> <a href="ShutdownCommand.html">SHUTDOWN</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/CommandReference.html b/doc/CommandReference.html new file mode 100644 index 000000000..18b00924a --- /dev/null +++ b/doc/CommandReference.html @@ -0,0 +1,44 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>CommandReference: Contents</b><br> <a href="#Redis Command Reference">Redis Command Reference</a><br> <a href="#Connection handling">Connection handling</a><br> <a href="#Commands operating on string values">Commands operating on string values</a><br> <a href="#Commands operating on the key space">Commands operating on the key space</a><br> <a href="#Commands operating on lists">Commands operating on lists</a><br> <a href="#Commands operating on sets">Commands operating on sets</a><br> <a href="#Multiple databases handling commands">Multiple databases handling commands</a><br> <a href="#Sorting">Sorting</a><br> <a href="#Persistence control commands">Persistence control commands</a><br> <a href="#Remote server control commands">Remote server control commands</a> + </div> + + <h1 class="wikiname">CommandReference</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="Redis Command Reference">Redis Command Reference</a></h1>Every command name links to a specific wiki page describing the behavior of the command.<h2><a name="Connection handling">Connection handling</a></h2><ul><li> <a href="QuitCommand.html">QUIT</a> <code name="code" class="python">close the connection</code></li></ul> +<h2><a name="Commands operating on string values">Commands operating on string values</a></h2><ul><li> <a href="SetCommand.html">SET</a> <i>key</i> <i>value</i> <code name="code" class="python">set a key to a string value</code></li><li> <a href="GetCommand.html">GET</a> <i>key</i> <code name="code" class="python">return the string value of the key</code></li><li> <a href="SetnxCommand.html">SETNX</a> <i>key</i> <i>value</i> <code name="code" class="python">set a key to a string value if the key does not exist</code></li><li> <a href="IncrCommand.html">INCR</a> <i>key</i> <code name="code" class="python">increment the integer value of key</code></li><li> <a href="IncrCommand.html">INCRBY</a> <i>key</i> <i>integer</i><code name="code" class="python"> increment the integer value of key by integer</code></li><li> <a href="IncrCommand.html">INCR</a> <i>key</i> <code name="code" class="python">decrement the integer value of key</code></li><li> <a href="IncrCommand.html">DECRBY</a> <i>key</i> <i>integer</i> <code name="code" class="python">decrement the integer value of key by integer</code></li><li> <a href="ExistsCommand.html">EXISTS</a> <i>key</i> <code name="code" class="python">test if a key exists</code></li><li> <a href="DelCommand.html">DEL</a> <i>key</i> <code name="code" class="python">delete a key</code></li><li> <a href="TypeCommand.html">TYPE</a> <i>key</i> <code name="code" class="python">return the type of the value stored at key</code></li></ul> +<h2><a name="Commands operating on the key space">Commands operating on the key space</a></h2><ul><li> <a href="KeysCommand.html">KEYS</a> <i>pattern</i> <code name="code" class="python">return all the keys matching a given pattern</code></li><li> <a href="RandomkeyCommand.html">RANDOMKEY</a> <code name="code" class="python">return a random key from the key space</code></li><li> <a href="RenameCommand.html">RENAME</a> <i>oldname</i> <i>newname</i> <code name="code" class="python">rename the old key in the new one, destroing the newname key if it already exists</code></li><li> <a href="RenamenxCommand.html">RENAMENX</a> <i>oldname</i> <i>newname</i> <code name="code" class="python">rename the old key in the new one, if the newname key does not already exist</code></li><li> <a href="Dbsize.html">DBSIZE</a> <code name="code" class="python">return the number of keys in the current db</code></li></ul> +<h2><a name="Commands operating on lists">Commands operating on lists</a></h2><ul><li> <a href="RpushCommand.html">RPUSH</a> <i>key</i> <i>value</i> <code name="code" class="python">Append an element to the tail of the List value at key</code></li><li> <a href="RpushCommand.html">LPUSH</a> <i>key</i> <i>value</i> <code name="code" class="python">Append an element to the head of the List value at key</code></li><li> <a href="LlenCommand.html">LLEN</a> <i>key</i> <code name="code" class="python">Return the length of the List value at key</code></li><li> <a href="LrangeCommand.html">LRANGE</a> <i>key</i> <i>start</i> <i>end</i> <code name="code" class="python">Return a range of elements from the List at key</code></li><li> <a href="LtrimCommand.html">LTRIM</a> <i>key</i> <i>start</i> <i>end</i> <code name="code" class="python">Trim the list at key to the specified range of elements</code></li><li> <a href="LindexCommand.html">LINDEX</a> <i>key</i> <i>index</i> <code name="code" class="python">Return the element at index position from the List at key</code></li><li> <a href="LsetCommand.html">LSET</a> <i>key</i> <i>index</i> <i>value</i> <code name="code" class="python">Set a new value as the element at index position of the List at key</code></li><li> <a href="LremCommand.html">LREM</a> <i>key</i> <i>count</i> <i>value</i> <code name="code" class="python">Remove the first-N, last-N, or all the elements matching value from the List at key</code></li><li> <a href="LpopCommand.html">LPOP</a> <i>key</i> <code name="code" class="python">Return and remove (atomically) the first element of the List at key</code></li><li> <a href="LpopCommand.html">RPOP</a> <i>key</i> <code name="code" class="python">Return and remove (atomically) the last element of the List at key</code></li></ul> +<h2><a name="Commands operating on sets">Commands operating on sets</a></h2><ul><li> <a href="SaddCommand.html">SADD</a> <i>key</i> <i>member</i> <code name="code" class="python">Add the specified member to the Set value at key</code></li><li> <a href="SremCommand.html">SREM</a> <i>key</i> <i>member</i> <code name="code" class="python">Remove the specified member from the Set value at key</code></li><li> <a href="ScardCommand.html">SCARD</a> <i>key</i> <code name="code" class="python">Return the number of elements (the cardinality) of the Set at key</code></li><li> <a href="SismemberCommand.html">SISMEMBER</a> <i>key</i> <i>member</i> <code name="code" class="python">Test if the specified value is a member of the Set at key</code></li><li> <a href="SinterCommand.html">SINTER</a> <i>key1</i> <i>key2</i> ... <i>keyN</i> <code name="code" class="python">Return the intersection between the Sets stored at key1, key2, ..., keyN</code></li><li> <a href="SinterCommand.html">SINTERSTORE</a> <i>dstkey</i> <i>key1</i> <i>key2</i> ... <i>keyN</i> <code name="code" class="python">Compute the intersection between the Sets stored at key1, key2, ..., keyN, and store the resulting Set at dstkey</code></li><li> <a href="SmembersCommand.html">SMEMBERS</a> <i>key</i> <code name="code" class="python">Return all the members of the Set value at key</code></li></ul> +<h2><a name="Multiple databases handling commands">Multiple databases handling commands</a></h2><ul><li> <a href="SelectCommand.html">SELECT</a> <i>index</i> <code name="code" class="python">Select the DB having the specified index</code></li><li> <a href="MoveCommand.html">MOVE</a> <i>key</i> <i>dbindex</i> <code name="code" class="python">Move the key from the currently selected DB to the DB having as index dbindex</code></li><li> <a href="FlushdbCommand.html">FLUSHDB</a> <code name="code" class="python">Remove all the keys of the currently selected DB</code></li><li> <a href="FlushallCommand.html">FLUSHALL</a> <code name="code" class="python">Remove all the keys from all the databases</code></li></ul> +<h2><a name="Sorting">Sorting</a></h2><ul><li> <a href="SortCommand.html">SORT</a> <i>key</i> BY <i>pattern</i> LIMIT <i>start</i> <i>end</i> GET <i>pattern</i> ASC|DESC ALPHA <code name="code" class="python">Sort a Set or a List accordingly to the specified parameters</code></li></ul> +<h2><a name="Persistence control commands">Persistence control commands</a></h2><ul><li> <a href="SaveCommand.html">SAVE</a> <code name="code" class="python">Synchronously save the DB on disk</code></li><li> <a href="BgsaveCommand.html">BGSAVE</a> <code name="code" class="python">Asynchronously save the DB on disk</code></li><li> <a href="LastsaveCommand.html">LASTSAVE</a> <code name="code" class="python">Return the UNIX time stamp of the last successfully saving of the dataset on disk</code></li><li> <a href="ShutdownCommand.html">SHUTDOWN</a> <code name="code" class="python">Synchronously save the DB on disk, then shutdown the server</code></li></ul> +<h2><a name="Remote server control commands">Remote server control commands</a></h2><ul><li> <a href="InfoCommand.html">INFO</a> <code name="code" class="python">provide information and statistics about the server</code></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/Credits.html b/doc/Credits.html new file mode 100644 index 000000000..b00cfa264 --- /dev/null +++ b/doc/Credits.html @@ -0,0 +1,36 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>Credits: Contents</b><br> <a href="#Credits">Credits</a> + </div> + + <h1 class="wikiname">Credits</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="Credits">Credits</a></h1><ul><li> The Redis server was designed and written by <a href="http://invece.org" target="_blank">Salvatore Sanfilippo (aka antirez)</a></li><li> The Ruby client library was written by <a href="http://brainspl.at/" target="_blank">Ezra Zygmuntowicz (aka ezmobius)</a></li><li> The Python and PHP client libraries were written by <a href="http://qix.it" target="_blank">Ludovico Magnocavallo (aka ludo)</a></li><li> The Erlang client library was written by <a href="http://www.adroll.com/" target="_blank">Valentino Volonghi of Adroll</a></li><li> <b>brettbender</b> found and fixed a but in sds.c that caused the server to crash at least on 64 bit systems, and anyway to be buggy since we used the same vararg thing against vsprintf without to call va_start and va_end every time.</li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/DbsizeCommand.html b/doc/DbsizeCommand.html new file mode 100644 index 000000000..2c3e796e1 --- /dev/null +++ b/doc/DbsizeCommand.html @@ -0,0 +1,38 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>DbsizeCommand: Contents</b><br> <a href="#DBSIZE">DBSIZE</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">DbsizeCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="DBSIZE">DBSIZE</a></h1><blockquote>Return the number of keys in the currently selected database.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SelectCommand.html">SELECT</a></li><li> <a href="InfoCommand.html">INFO</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/DelCommand.html b/doc/DelCommand.html new file mode 100644 index 000000000..4867af9b2 --- /dev/null +++ b/doc/DelCommand.html @@ -0,0 +1,42 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>DelCommand: Contents</b><br> <a href="#DEL _key_">DEL _key_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">DelCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="DEL _key_">DEL _key_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Remove the specified key. If the key does not existno operation is performed. The command always returns success.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +1 if the key was removed +0 if the key does not exist +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SetCommand.html">SET</a></li><li> <a href="GetCommand.html">GET</a></li><li> <a href="ExistsCommand.html">EXISTS</a></li><li> <a href="LdelCommand.html">LDEL</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/DesignPatterns.html b/doc/DesignPatterns.html new file mode 100644 index 000000000..411739f1a --- /dev/null +++ b/doc/DesignPatterns.html @@ -0,0 +1,37 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>DesignPatterns: Contents</b> + </div> + + <h1 class="wikiname">DesignPatterns</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + Use random keys instead of incremental keys in order to avoid a single-key that gets incremented by many servers. This can can't be distributed among servers. + + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/ExistsCommand.html b/doc/ExistsCommand.html new file mode 100644 index 000000000..32cc99782 --- /dev/null +++ b/doc/ExistsCommand.html @@ -0,0 +1,42 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>ExistsCommand: Contents</b><br> <a href="#EXISTS _key_">EXISTS _key_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">ExistsCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="EXISTS _key_">EXISTS _key_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Test if the specified key exists. The command returns"0" if the key exists, otherwise "1" is returned.Note that even keys set with an empty string as value willreturn "1".</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +1 if the key exists. +0 if the key does not exist. +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SetnxCommand.html">SETNX</a> is a <code name="code" class="python">SET if not EXISTS</code> atomic operation.</li><li> <a href="SismemberCommand.html">SISMEMBER</a> test if an element is a member of a Set.</li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/FAQ.html b/doc/FAQ.html new file mode 100644 index 000000000..a7f8dcaf3 --- /dev/null +++ b/doc/FAQ.html @@ -0,0 +1,47 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>FAQ: Contents</b><br> <a href="#Why I need Redis if there is already memcachedb, Tokyo Cabinet, ...?">Why I need Redis if there is already memcachedb, Tokyo Cabinet, ...?</a><br> <a href="#Isn't this key-value thing just hype?">Isn't this key-value thing just hype?</a><br> <a href="#Can I backup a Redis DB while the server is working?">Can I backup a Redis DB while the server is working?</a><br> <a href="#What's the Redis memory footprint?">What's the Redis memory footprint?</a><br> <a href="#I like Redis high level operations and features, but I don't like it takes everything in memory and I can't have a dataset larger the memory. Plans to change this?">I like Redis high level operations and features, but I don't like it takes everything in memory and I can't have a dataset larger the memory. Plans to change this?</a><br> <a href="#Ok but I absolutely need to have a DB larger than memory, still I need the Redis features">Ok but I absolutely need to have a DB larger than memory, still I need the Redis features</a><br> <a href="#What happens if Redis runs out of memory?">What happens if Redis runs out of memory?</a><br> <a href="#What Redis means actually?">What Redis means actually?</a><br> <a href="#Why did you started the Redis project?">Why did you started the Redis project?</a> + </div> + + <h1 class="wikiname">FAQ</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="Why I need Redis if there is already memcachedb, Tokyo Cabinet, ...?">Why I need Redis if there is already memcachedb, Tokyo Cabinet, ...?</a></h1>Memcachedb is basically memcached done persistent. Redis is a different evolution +path in the key-value DBs, the idea is that the main advantages of key-value DBs +are retained even without a so severe loss of comfort of plain key-value DBs. +So Redis offers more features:<br/><br/><ul><li> Keys can store different data types, not just strings. Notably Lists and Sets. For example if you want to use Redis as a log storage system for different computers every computer can just <code name="code" class="python">RPUSH data to the computer_ID key</code>. Don't want to save more than 1000 log lines per computer? Just issue a <code name="code" class="python">LTRIM computer_ID 0 999</code> command to trim the list after every push.</li></ul> +<ul><li> Another example is about Sets. Imagine to build a social news site like <a href="http://reddit.com" target="_blank">Reddit</a>. Every time a user upvote a given news you can just add to the news_ID_upmods key holding a value of type SET the id of the user that did the upmodding. Sets can also be used to index things. Every key can be a tag holding a SET with the IDs of all the objects associated to this tag. Using Redis set intersection you obtain the list of IDs having all this tags at the same time.</li></ul> +<ul><li> We wrote a <a href="http://retwis.antirez.com" target="_blank">simple Twitter Clone</a> using just Redis as database. Download the source code from the download section and imagine to write it with a plain key-value DB without support for lists and sets... it's <b>much</b> harder.</li></ul> +<ul><li> Multiple DBs. Using the SELECT command the client can select different datasets. This is useful because Redis provides a MOVE atomic primitive that moves a key form a DB to another one, if the target DB already contains such a key it returns an error: this basically means a way to perform locking in distributed processing.</li></ul> +<ul><li> <b>So what is Redis really about?</b> The User interface with the programmer. Redis aims to export to the programmer the right tools to model a wide range of problems. <b>Sets, Lists with O(1) push operation, lrange and ltrim, server-side fast intersection between sets, are primitives that allow to model complex problems with a key value database</b>.</li></ul> +<h1><a name="Isn't this key-value thing just hype?">Isn't this key-value thing just hype?</a></h1>I imagine key-value DBs, in the short term future, to be used like you use memory in a program, with lists, hashes, and so on. With Redis it's like this, but this special kind of memory containing your data structures is shared, atomic, persistent.<br/><br/>When we write code it is obvious, when we take data in memory, to use the most sensible data structure for the work, right? Incredibly when data is put inside a relational DB this is no longer true, and we create an absurd data model even if our need is to put data and get this data back in the same order we put it inside (an ORDER BY is required when the data should be already sorted. Strange, dont' you think?).<br/><br/>Key-value DBs bring this back at home, to create sensible data models and use the right data structures for the problem we are trying to solve.<h1><a name="Can I backup a Redis DB while the server is working?">Can I backup a Redis DB while the server is working?</a></h1>Yes you can. When Redis saves the DB it actually creates a temp file, then rename(2) that temp file name to the destination file name. So even while the server is working it is safe to save the database file just with the <i>cp</i> unix command. Note that you can use master-slave replication in order to have redundancy of data, but if all you need is backups, cp or scp will do the work pretty well.<h1><a name="What's the Redis memory footprint?">What's the Redis memory footprint?</a></h1>Worst case scenario: 1 Million keys with the key being the natural numbers from 0 to 999999 and the string "Hello World" as value use 100MB on my Intel macbook (32bit). Note that the same data stored linearly in an unique string takes something like 16MB, this is the norm because with small keys and values there is a lot of overhead. Memcached will perform similarly.<br/><br/>With large keys/values the ratio is much better of course.<br/><br/>64 bit systems will use much more memory than 32 bit systems to store the same keys, especially if the keys and values are small, this is because pointers takes 8 bytes in 64 bit systems. But of course the advantage is that you can have a lot of memory in 64 bit systems, so to run large Redis servers a 64 bit system is more or less required.<h1><a name="I like Redis high level operations and features, but I don't like it takes everything in memory and I can't have a dataset larger the memory. Plans to change this?">I like Redis high level operations and features, but I don't like it takes everything in memory and I can't have a dataset larger the memory. Plans to change this?</a></h1>The whole key-value hype started for a reason: performances. Redis takes the whole dataset in memory and writes asynchronously on disk in order to be very fast, you have the best of both worlds: hyper-speed and persistence of data, but the price to pay is exactly this, that the dataset must fit on your computers RAM.<br/><br/>If the data is larger then memory, and this data is stored on disk, what happens is that the bottleneck of the disk I/O speed will start to ruin the performances. Maybe not in benchmarks, but once you have real load with distributed key accesses the data must come from disk, and the disk is damn slow. Not only, but Redis supports higher level data structures than the plain values. To implement this things on disk is even slower.<br/><br/>Redis will always continue to hold the whole dataset in memory because this days scalability requires to use RAM as storage media, and RAM is getting cheaper and cheaper. Today it is common for an entry level server to have 16 GB of RAM! And in the 64-bit era there are no longer limits to the amount of RAM you can have in theory.<h1><a name="Ok but I absolutely need to have a DB larger than memory, still I need the Redis features">Ok but I absolutely need to have a DB larger than memory, still I need the Redis features</a></h1>One possible solution is to use both MySQL and Redis at the same time, basically take the state on Redis, and all the things that get accessed very frequently: user auth tokens, Redis Lists with chronologically ordered IDs of the last N-comments, N-posts, and so on. Then use MySQL as a simple storage engine for larger data, that is just create a table with an auto-incrementing ID as primary key and a large BLOB field as data field. Access MySQL data only by primary key (the ID). The application will run the high traffic queries against Redis but when there is to take the big data will ask MySQL for specific resources IDs.<h1><a name="What happens if Redis runs out of memory?">What happens if Redis runs out of memory?</a></h1>With modern operating systems malloc() returning NULL is not common, usually the server will start swapping and Redis performances will be disastrous so you'll know it's time to use more Redis servers or get more RAM.<br/><br/>However it is planned to add a configuration directive to tell Redis to stop accepting queries but instead to SAVE the latest data and quit if it is using more than a given amount of memory. Also the new INFO command (work in progress in this days) will report the amount of memory Redis is using so you can write scripts that monitor your Redis servers checking for critical conditions.<br/><br/>Update: redis SVN is able to know how much memory it is using and report it via the <a href="InfoCommand.html">INFO</a> command.<h1><a name="What Redis means actually?">What Redis means actually?</a></h1>Redis means two things: +<ul><li> it's a joke on the word Redistribute (instead to use just a Relational DB redistribute your workload among Redis servers)</li><li> it means REmote DIctionary Server</li></ul> +<h1><a name="Why did you started the Redis project?">Why did you started the Redis project?</a></h1>In order to scale <a href="http://lloogg.com" target="_blank">LLOOGG</a>. But after I got the basic server working I liked the idea to share the work with other guys, and Redis was turned into an open source project. + + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/FlushallCommand.html b/doc/FlushallCommand.html new file mode 100644 index 000000000..85c842257 --- /dev/null +++ b/doc/FlushallCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>FlushallCommand: Contents</b><br> <a href="#FLUSHALL">FLUSHALL</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">FlushallCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="FLUSHALL">FLUSHALL</a></h1> +<blockquote>Delete all the keys of all the existing databases, not just the currently selected one. This command never fails.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="FlushdbCommand.html">FLUSHDB</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/FlushdbCommand.html b/doc/FlushdbCommand.html new file mode 100644 index 000000000..6bf4ca04b --- /dev/null +++ b/doc/FlushdbCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>FlushdbCommand: Contents</b><br> <a href="#FLUSHDB">FLUSHDB</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">FlushdbCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="FLUSHDB">FLUSHDB</a></h1> +<blockquote>Delete all the keys of the currently selected DB. This command never fails.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="FlushallCommand.html">FLUSHALL</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/GetCommand.html b/doc/GetCommand.html new file mode 100644 index 000000000..50d6bf344 --- /dev/null +++ b/doc/GetCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>GetCommand: Contents</b><br> <a href="#GET _key_">GET _key_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">GetCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="GET _key_">GET _key_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Get the value of the specified key. If the keydoes not exist the special value 'nil' is returned.If the value stored at <i>key</i> is not a string an erroris returned because GET can only handle string values.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Bulk reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SetCommand.html">SET</a></li><li> <a href="SetnxCommand.html">SETNX</a></li><li> <a href="IncrCommand.html">INCR</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/IncrCommand.html b/doc/IncrCommand.html new file mode 100644 index 000000000..676d06cbe --- /dev/null +++ b/doc/IncrCommand.html @@ -0,0 +1,43 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>IncrCommand: Contents</b><br> <a href="#INCR _key_">INCR _key_</a><br> <a href="#INCRBY _key_ _integer_">INCRBY _key_ _integer_</a><br> <a href="#DECR _key_ _integer_">DECR _key_ _integer_</a><br> <a href="#DECRBY _key_ _integer_">DECRBY _key_ _integer_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">IncrCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="INCR _key_">INCR _key_</a></h1> +<h1><a name="INCRBY _key_ _integer_">INCRBY _key_ _integer_</a></h1> +<h1><a name="DECR _key_ _integer_">DECR _key_ _integer_</a></h1> +<h1><a name="DECRBY _key_ _integer_">DECRBY _key_ _integer_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Increment or decrement the number stored at <i>key</i> by one. If the key doesnot exist or contains a value of a wrong type, set the key to thevalue of "0" before to perform the increment or decrement operation.</blockquote> +<blockquote>INCRBY and DECRBY work just like INCR and DECR but instead toincrement/decrement by 1 the increment/decrement is <i>integer</i>.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, this commands will reply with the new value of <i>key</i> after the increment or decrement.<h2><a name="See also">See also</a></h2> +<ul><li> <a href="GetCommand.html">GET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/InfoCommand.html b/doc/InfoCommand.html new file mode 100644 index 000000000..325deff47 --- /dev/null +++ b/doc/InfoCommand.html @@ -0,0 +1,50 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>InfoCommand: Contents</b><br> <a href="#INFO">INFO</a><br> <a href="#Return value">Return value</a><br> <a href="#Notes">Notes</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">InfoCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="INFO">INFO</a></h1><blockquote>The info command returns different information and statistics about the server in an format that's simple to parse by computers and easy to red by huamns.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Bulk reply</a>, specifically in the following format:<br/><br/><pre class="codeblock python" name="code"> +edis_version:0.07 +connected_clients:1 +connected_slaves:0 +used_memory:3187 +changes_since_last_save:0 +last_save_time:1237655729 +total_connections_received:1 +total_commands_processed:1 +uptime_in_seconds:25 +uptime_in_days:0 +</pre>All the fields are in the form <code name="code" class="python">field:value</code><h2><a name="Notes">Notes</a></h2><ul><li> <code name="code" class="python">used_memory</code> is returned in bytes, and is the total number of bytes allocated by the program using <code name="code" class="python">malloc</code>.</li><li> <code name="code" class="python">uptime_in_days</code> is redundant since the uptime in seconds contains already the full uptime information, this field is only mainly present for humans.</li><li> <code name="code" class="python">changes_since_last_save</code> does not refer to the number of key changes, but to the number of operations that produced some kind of change in the dataset.</li></ul> +<h2><a name="See also">See also</a></h2> +<ul><li> <a href="LastsaveCommand.html">LASTSAVE</a></li><li> <a href="DbsizeCommand.html">DBSIZE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/KeysCommand.html b/doc/KeysCommand.html new file mode 100644 index 000000000..98718fc0c --- /dev/null +++ b/doc/KeysCommand.html @@ -0,0 +1,42 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>KeysCommand: Contents</b><br> <a href="#KEYS _pattern_">KEYS _pattern_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">KeysCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="KEYS _pattern_">KEYS _pattern_</a></h1> +<i>Time complexity: O(n) (with n being the number of keys in the DB, and assuming keys and pattern of limited length)</i><blockquote>Returns all the keys matching the glob-style <i>pattern</i> asspace separated strings. For example if you have in thedatabase the keys "foo" and "foobar" the command "KEYS foo<code name="code" class="python">*</code>"will return "foo foobar".</blockquote> +<blockquote>Note that while the time complexity for this operation is O(n)the constant times are pretty low. For example Redis runningon an entry level laptop can scan a 1 million keys databasein 40 milliseconds. Still it's better to consider this one ofthe slow commands that may ruin the DB performance if not usedwith care.</blockquote> +Glob style patterns examples: +<ul><li> h?llo will match hello hallo hhllo</li><li> h<b>llo will match hllo heeeello +<blockquote>* h<a href="ae.html">ae</a>llo will match hello and hallo, but not hillo</blockquote>Use \ to escape special chars if you want to match them verbatim.<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Bulk reply</a>, specifically a string in the form of space separated list of keys. Note that most client libraries will return an Array of keys and not a single string with space separated keys (that is, split by " " is performed in the client library usually).<h2><a name="See also">See also</a></h2> +<blockquote>* <a href="RandomkeyCommand.html">RANDOMKEY</a> to get the name of a randomly selected key in O(1).</blockquote></b></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/LastsaveCommand.html b/doc/LastsaveCommand.html new file mode 100644 index 000000000..c10b80245 --- /dev/null +++ b/doc/LastsaveCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>LastsaveCommand: Contents</b><br> <a href="#LASTSAVE">LASTSAVE</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">LastsaveCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="LASTSAVE">LASTSAVE</a></h1> +<blockquote>Return the UNIX TIME of the last DB save executed with success.A client may check if a <a href="BgsaveCommand.html">BGSAVE</a> command succeeded reading the LASTSAVEvalue, then issuing a <a href="BgsaveCommand.html">BGSAVE</a> command and checking at regular intervalsevery N seconds if LASTSAVE changed.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically an UNIX time stamp.<h2><a name="See also">See also</a></h2> +<ul><li> <a href="BgsaveCommand.html">BGSAVE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/LindexCommand.html b/doc/LindexCommand.html new file mode 100644 index 000000000..8116338a4 --- /dev/null +++ b/doc/LindexCommand.html @@ -0,0 +1,41 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>LindexCommand: Contents</b><br> <a href="#LINDEX _key_ _index_">LINDEX _key_ _index_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">LindexCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="LINDEX _key_ _index_">LINDEX _key_ _index_</a></h1> +<i>Time complexity: O(n) (with n being the length of the list)</i><blockquote>Return the specified element of the list stored at the specifiedkey. 0 is the first element, 1 the second and so on. Negative indexesare supported, for example -1 is the last element, -2 the penultimateand so on.</blockquote> +<blockquote>If the value stored at key is not of list type an error is returned.If the index is out of range an empty string is returned.</blockquote> +<blockquote>Note that even if the average time complexity is O(n) asking forthe first or the last element of the list is O(1).</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Bulk reply</a>, specifically the requested element.<h2><a name="See also">See also</a></h2> +<ul><li> <a href="LlenCommand.html">LLEN</a></li><li> <a href="LrangeCommand.html">LRANGE</a></li><li> <a href="LtrimCommand.html">LTRIM</a></li><li> <a href="LdelCommand.html">LDEL</a></li><li> <a href="LindexCommand.html">LINDEX</a></li><li> <a href="LsetCommand.html">LSET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/LlenCommand.html b/doc/LlenCommand.html new file mode 100644 index 000000000..e1284a31a --- /dev/null +++ b/doc/LlenCommand.html @@ -0,0 +1,42 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>LlenCommand: Contents</b><br> <a href="#LLEN _key_">LLEN _key_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">LlenCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="LLEN _key_">LLEN _key_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Return the length of the list stored at the specified key. If thekey does not exist zero is returned (the same behaviour as forempty lists). If the value stored at <i>key</i> is not a list an error is returned.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +The length of the list as an integer `>=` 0 if the operation succeeded +-2 if the specified key does not hold a list value +</pre>Note that library clients should raise an error if -2 is returned by the Redis server instead to pass the negative value back to the caller.<h2><a name="See also">See also</a></h2> +<ul><li> <a href="LlenCommand.html">LLEN</a></li><li> <a href="LrangeCommand.html">LRANGE</a></li><li> <a href="LtrimCommand.html">LTRIM</a></li><li> <a href="LdelCommand.html">LDEL</a></li><li> <a href="LindexCommand.html">LINDEX</a></li><li> <a href="LsetCommand.html">LSET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/LpopCommand.html b/doc/LpopCommand.html new file mode 100644 index 000000000..8750a6681 --- /dev/null +++ b/doc/LpopCommand.html @@ -0,0 +1,41 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>LpopCommand: Contents</b><br> <a href="#LPOP _key_">LPOP _key_</a><br> <a href="#RPOP _key_">RPOP _key_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">LpopCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="LPOP _key_">LPOP _key_</a></h1> +<h1><a name="RPOP _key_">RPOP _key_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Atomically return and remove the first (LPOP) or last (RPOP) elementof the list. For example if the list contains the elements "a","b","c" LPOPwill return "a" and the list will become "b","c".</blockquote> +<blockquote>If the <i>key</i> does not exist or the list is already empty the specialvalue 'nil' is returned.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Bulk reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="LlenCommand.html">LLEN</a></li><li> <a href="LrangeCommand.html">LRANGE</a></li><li> <a href="LtrimCommand.html">LTRIM</a></li><li> <a href="LdelCommand.html">LDEL</a></li><li> <a href="LindexCommand.html">LINDEX</a></li><li> <a href="LsetCommand.html">LSET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/LrangeCommand.html b/doc/LrangeCommand.html new file mode 100644 index 000000000..2df5cc6f6 --- /dev/null +++ b/doc/LrangeCommand.html @@ -0,0 +1,42 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>LrangeCommand: Contents</b><br> <a href="#LRANGE _key_ _start_ _end_">LRANGE _key_ _start_ _end_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">LrangeCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="LRANGE _key_ _start_ _end_">LRANGE _key_ _start_ _end_</a></h1> +<i>Time complexity: O(n) (with n being the length of the range)</i><blockquote>Return the specified elements of the list stored at the specifiedkey. Start and end are zero-based indexes. 0 is the first elementof the list (the list head), 1 the next element and so on.</blockquote> +<blockquote>For example LRANGE foobar 0 2 will return the first three elementsof the list.</blockquote> +<blockquote>_start_ and <i>end</i> can also be negative numbers indicating offsetsfrom the end of the list. For example -1 is the last element ofthe list, -2 the penultimate element and so on.</blockquote> +<blockquote>Indexes out of range will not produce an error: if start is overthe end of the list, or start <code name="code" class="python">></code> end, an empty list is returned.If end is over the end of the list Redis will threat it just likethe last element of the list.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Multi bulk reply</a>, specifically a list of elements in the specified range.<h2><a name="See also">See also</a></h2> +<ul><li> <a href="LlenCommand.html">LLEN</a></li><li> <a href="LrangeCommand.html">LRANGE</a></li><li> <a href="LtrimCommand.html">LTRIM</a></li><li> <a href="LdelCommand.html">LDEL</a></li><li> <a href="LindexCommand.html">LINDEX</a></li><li> <a href="LsetCommand.html">LSET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/LremCommand.html b/doc/LremCommand.html new file mode 100644 index 000000000..a2441ba2b --- /dev/null +++ b/doc/LremCommand.html @@ -0,0 +1,43 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>LremCommand: Contents</b><br> <a href="#LREM _key_ _count_ _value_">LREM _key_ _count_ _value_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">LremCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="LREM _key_ _count_ _value_">LREM _key_ _count_ _value_</a></h1> +<i>Time complexity: O(N) (with N being the length of the list)</i><blockquote>Remove the first <i>count</i> occurrences of the <i>value</i> element from the list.If <i>count</i> is zero all the elements are removed. If <i>count</i> is negativeelements are removed from tail to head, instead to go from head to tailthat is the normal behaviour. So for example LREM with count -2 and_hello_ as value to remove against the list (a,b,c,hello,x,hello,hello) willlave the list (a,b,c,hello,x). The number of removed elements is returnedas an integer, see below for more information aboht the returned value.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer Reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +The number of removed elements if the operation succeeded +-1 if the specified key does not exist +-2 if the specified key does not hold a list value +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="LlenCommand.html">LLEN</a></li><li> <a href="LrangeCommand.html">LRANGE</a></li><li> <a href="LtrimCommand.html">LTRIM</a></li><li> <a href="LdelCommand.html">LDEL</a></li><li> <a href="LindexCommand.html">LINDEX</a></li><li> <a href="LsetCommand.html">LSET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/LsetCommand.html b/doc/LsetCommand.html new file mode 100644 index 000000000..064da293d --- /dev/null +++ b/doc/LsetCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>LsetCommand: Contents</b><br> <a href="#LSET _key_ _index_ _value_">LSET _key_ _index_ _value_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">LsetCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="LSET _key_ _index_ _value_">LSET _key_ _index_ _value_</a></h1> +<i>Time complexity: O(N) (with N being the length of the list)</i><blockquote>Set the list element at <i>index</i> (see LINDEX for information about the_index_ argument) with the new <i>value</i>. Out of range indexes willgenerate an error. Note that setting the first or last elements ofthe list is O(1).</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="LlenCommand.html">LLEN</a></li><li> <a href="LrangeCommand.html">LRANGE</a></li><li> <a href="LtrimCommand.html">LTRIM</a></li><li> <a href="LdelCommand.html">LDEL</a></li><li> <a href="LindexCommand.html">LINDEX</a></li><li> <a href="LsetCommand.html">LSET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/LtrimCommand.html b/doc/LtrimCommand.html new file mode 100644 index 000000000..a492fccb2 --- /dev/null +++ b/doc/LtrimCommand.html @@ -0,0 +1,47 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>LtrimCommand: Contents</b><br> <a href="#LTRIM _key_ _start_ _end_">LTRIM _key_ _start_ _end_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">LtrimCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="LTRIM _key_ _start_ _end_">LTRIM _key_ _start_ _end_</a></h1> +<i>Time complexity: O(n) (with n being len of list - len of range)</i><blockquote>Trim an existing list so that it will contain only the specifiedrange of elements specified. Start and end are zero-based indexes.0 is the first element of the list (the list head), 1 the next elementand so on.</blockquote> +<blockquote>For example LTRIM foobar 0 2 will modify the list stored at foobarkey so that only the first three elements of the list will remain.</blockquote> +<blockquote>_start_ and <i>end</i> can also be negative numbers indicating offsetsfrom the end of the list. For example -1 is the last element ofthe list, -2 the penultimate element and so on.</blockquote> +<blockquote>Indexes out of range will not produce an error: if start is overthe end of the list, or start > end, an empty list is left as value.If end over the end of the list Redis will threat it just likethe last element of the list.</blockquote> +<blockquote>Hint: the obvious use of LTRIM is together with LPUSH/RPUSH. For example:</blockquote> +<pre class="codeblock python" name="code"> + LPUSH mylist <someelement> + LTRIM mylist 0 99 +</pre><blockquote>The above two commands will push elements in the list taking care thatthe list will not grow without limits. This is very useful when usingRedis to store logs for example. It is important to note that when usedin this way LTRIM is an O(1) operation because in the average casejust one element is removed from the tail of the list.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="LlenCommand.html">LLEN</a></li><li> <a href="LrangeCommand.html">LRANGE</a></li><li> <a href="LtrimCommand.html">LTRIM</a></li><li> <a href="LdelCommand.html">LDEL</a></li><li> <a href="LindexCommand.html">LINDEX</a></li><li> <a href="LsetCommand.html">LSET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/MoveCommand.html b/doc/MoveCommand.html new file mode 100644 index 000000000..f3252f845 --- /dev/null +++ b/doc/MoveCommand.html @@ -0,0 +1,42 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>MoveCommand: Contents</b><br> <a href="#MOVE _key_ _dbindex_">MOVE _key_ _dbindex_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">MoveCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="MOVE _key_ _dbindex_">MOVE _key_ _dbindex_</a></h1> +<blockquote>Move the specified key from the currently selected DB to the specifieddestination DB. Note that this command returns 1 only if the key wassuccessfully moved, and 0 if the target key was already there or if thesource key was not found at all, so it is possible to use MOVE as a lockingprimitive.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/>1 if the key was moved +0 if the key was not moved because already present on the target DB or was not found in the current DB. +-3 if the destination DB is the same as the source DB +-4 if the database index if out of range<h2><a name="See also">See also</a></h2> +<ul><li> <a href="SelectCommand.html">SELECT</a></li><li> <a href="RenameCommand.html">RENAME</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/ProtocolSpecification.html b/doc/ProtocolSpecification.html new file mode 100644 index 000000000..95d454ab9 --- /dev/null +++ b/doc/ProtocolSpecification.html @@ -0,0 +1,143 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>ProtocolSpecification: Contents</b><br> <a href="#Protocol Specification">Protocol Specification</a><br> <a href="#Networking layer">Networking layer</a><br> <a href="#Simple INLINE commands">Simple INLINE commands</a><br> <a href="#Bulk commands">Bulk commands</a><br> <a href="#Bulk replies">Bulk replies</a><br> <a href="#Bulk reply error reporting">Bulk reply error reporting</a><br> <a href="#Multi-Bulk replies">Multi-Bulk replies</a><br> <a href="#Nil elements in Multi-Bulk replies">Nil elements in Multi-Bulk replies</a><br> <a href="#Multi-Bulk replies errors">Multi-Bulk replies errors</a><br> <a href="#Status code reply">Status code reply</a><br> <a href="#Integer reply">Integer reply</a><br> <a href="#Single line reply">Single line reply</a><br> <a href="#Multiple commands and pipelining">Multiple commands and pipelining</a> + </div> + + <h1 class="wikiname">ProtocolSpecification</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="Protocol Specification">Protocol Specification</a></h1>The Redis protocol is a compromise between being easy to parse by a computer +and being easy to parse by an human. Before reading this section you are +strongly encouraged to read the "REDIS TUTORIAL" section of this README in order +to get a first feeling of the protocol playing with it by TELNET.<h2><a name="Networking layer">Networking layer</a></h2>A client connects to a Redis server creating a TCP connection to the port 6973. +Every redis command or data transmitted by the client and the server is +terminated by "\r\n" (CRLF).<h2><a name="Simple INLINE commands">Simple INLINE commands</a></h2>The simplest commands are the inline commands. This is an example of a +server/client chat (the server chat starts with S:, the client chat with C:)<br/><br/><pre class="codeblock python" name="code"> +C: PING +S: +PONG +</pre>An inline command is a CRLF-terminated string sent to the client. The server +usually replies to inline commands with a single line that can be a number +or a return code.<br/><br/>When the server replies with a status code (that is a one line reply just indicating if the operation succeeded or not), if the first character of the +reply is a "+" then the command succeeded, if it is a "-" then the following +part of the string is an error.<br/><br/>The following is another example of an INLINE command returning an integer:<br/><br/><pre class="codeblock python python" name="code"> +C: EXISTS somekey +S: 0 +</pre>Since 'somekey' does not exist the server returned '0'.<br/><br/>Note that the EXISTS command takes one argument. Arguments are separated +simply by spaces.<h2><a name="Bulk commands">Bulk commands</a></h2>A bulk command is exactly like an inline command, but the last argument +of the command must be a stream of bytes in order to send data to the server. +the "SET" command is a bulk command, see the following example:<br/><br/><pre class="codeblock python python python" name="code"> +C: SET mykey 6 +C: foobar +S: +OK +</pre>The last argument of the commnad is '6'. This specify the number of DATA +bytes that will follow (note that even this bytes are terminated by two +additional bytes of CRLF).<br/><br/>All the bulk commands are in this exact form: instead of the last argument +the number of bytes that will follow is specified, followed by the bytes, +and CRLF. In order to be more clear for the programmer this is the string +sent by the client in the above sample:<br/><br/><blockquote>"SET mykey 6\r\nfoobar\r\n"</blockquote> +<h2><a name="Bulk replies">Bulk replies</a></h2>The server may reply to an inline or bulk command with a bulk reply. See +the following example:<br/><br/><pre class="codeblock python python python python" name="code"> +C: GET mykey +S: 6 +S: foobar +</pre>A bulk reply is very similar to the last argument of a bulk command. The +server sends as the first line the number of bytes of the actual reply +followed by CRLF, then the bytes are sent followed by additional two bytes +for the final CRLF. The exact sequence sent by the server is:<br/><br/><blockquote>"6\r\nfoobar\r\n"</blockquote> +If the requested value does not exist the bulk reply will use the special +value 'nil' instead to send the line containing the number of bytes to read. +This is an example:<br/><br/><pre class="codeblock python python python python python" name="code"> +C: GET nonexistingkey +S: nil +</pre>The client library API should not return an empty string, but a nil object. +For example a Ruby library should return 'nil' while a C library should return +NULL.<h2><a name="Bulk reply error reporting">Bulk reply error reporting</a></h2>Bulk replies can signal errors, for example trying to use GET against a list +value is not permitted. Bulk replies use a negative bytes count in order to +signal an error. An error string of ABS(bytes_count) bytes will follow. See +the following example:<br/><br/><pre class="codeblock python python python python python python" name="code"> +S: GET alistkey +S: -38 +S: -ERR Requested element is not a string +</pre>-38 means: sorry your operation resulted in an error, but a 38 bytes string +that explains this error will follow. Client APIs should abort on this kind +of errors, for example a PHP client should call the die() function.<br/><br/>The following commands reply with a bulk reply: GET, KEYS, LINDEX, LPOP, RPOP<h2><a name="Multi-Bulk replies">Multi-Bulk replies</a></h2>Commands similar to LRANGE needs to return multiple values (every element +of the list is a value, and LRANGE needs to return more than a single element). This is accomplished using multiple bulk writes, +prefixed by an initial line indicating how many bulk writes will follow. +Example:<br/><br/><pre class="codeblock python python python python python python python" name="code"> +C: LRANGE mylist 0 3 +S: 4 +S: 3 +S: foo +S: 3 +S: bar +S: 5 +S: Hello +S: 5 +S: World +</pre>The first line the server sent is "4\r\n" in order to specify that four bulk +write will follow. Then every bulk write is transmitted.<br/><br/>If the specified key does not exist instead of the number of elements in the +list, the special value 'nil' is sent. Example:<br/><br/><pre class="codeblock python python python python python python python python" name="code"> +C: LRANGE nokey 0 1 +S: nil +</pre>A client library API SHOULD return a nil object and not an empty list when this +happens. This makes possible to distinguish between empty list and non existing ones.<h2><a name="Nil elements in Multi-Bulk replies">Nil elements in Multi-Bulk replies</a></h2>Single elements of a multi bulk reply may have -1 length, in order to signal that this elements are missing and not empty strings. This can happen with the SORT command when used with the GET <i>pattern</i> option when the specified key is missing. Example of a multi bulk reply containing an empty element:<br/><br/><pre class="codeblock python python python python python python python python python" name="code"> +S: 3 +S: 3 +S: foo +S: -1 +S: 3 +S: bar +</pre>The second element is nul. The client library should return something like this:<br/><br/><pre class="codeblock python python python python python python python python python python" name="code"> +["foo",nil,"bar"] +</pre><h2><a name="Multi-Bulk replies errors">Multi-Bulk replies errors</a></h2>Like bulk reply errors Multi-bulk reply errors are reported using a negative +count. Example:<br/><br/><pre class="codeblock python python python python python python python python python python python" name="code"> +C: LRANGE stringkey 0 1 +S: -38 +S: -ERR Requested element is not a string +</pre>The following commands reply with a multi-bulk reply: LRANGE, LINTER<br/><br/>Check the Bulk replies errors section for more information.<h2><a name="Status code reply">Status code reply</a></h2>As already seen a status code reply is in the form of a single line string +terminated by "\r\n". For example:<br/><br/><pre class="codeblock python python python python python python python python python python python python" name="code"> ++OK +</pre>and<br/><br/><pre class="codeblock python python python python python python python python python python python python python" name="code"> +-ERR no suck key +</pre>are two examples of status code replies. The first character of a status code reply is always "+" or "-".<br/><br/>The following commands reply with a status code reply: +PING, SET, SELECT, SAVE, BGSAVE, SHUTDOWN, RENAME, LPUSH, RPUSH, LSET, LTRIM<h2><a name="Integer reply">Integer reply</a></h2>This type of reply is just a CRLF terminated string representing an integer. For example "0\r\n", or "1000\r\n" are integer replies.<br/><br/>With commands like INCR or LASTSAVE using the integer reply to actually return a value there is no special meaning for the returned integer. It is just an incremental number for INCR, a UNIX time for LASTSAVE and so on.<br/><br/>Some commands like EXISTS will return 1 for true and 0 for false.<br/><br/>Other commands like SADD, SREM and SETNX will return 1 if the operation was actually done, 0 otherwise, and <b>a negative value</b> if the operation is invalid (for example SADD against a non-set value), accordingly to this table: +<pre class="codeblock python python python python python python python python python python python python python python" name="code"> +-1 no such key +-2 operation against the a key holding a value of the wrong type +-3 source and destiantion objects/dbs are the same +-4 argument out of range +</pre> +In all this cases it is mandatory that the client raises an error instead to pass the negative value to the caller. Please check the commands documentation for the exact behaviour.<br/><br/>The following commands will reply with an integer reply: SETNX, DEL, EXISTS, INCR, INCRBY, DECR, DECRBY, DBSIZE, LASTSAVE, RENAMENX, MOVE, LLEN, SADD, SREM, SISMEMBER, SCARD<br/><br/>The commands that will never return a negative integer (commands that can't fail) are: INCR, DECR, INCRBY, DECRBY, LASTSAVE, EXISTS, SETNX, DEL, DBSIZE.<h2><a name="Single line reply">Single line reply</a></h2>This replies are just single line strings terminated by CRLF. Only two commands reply in this way currently, RANDOMKEY and TYPE.<h2><a name="Multiple commands and pipelining">Multiple commands and pipelining</a></h2>A client can use the same connection in order to issue multiple commands. +Pipelining is supported so multiple commands can be sent with a single +write operation by the client, it is not needed to read the server reply +in order to issue the next command. All the replies can be read at the end.<br/><br/>Usually Redis server and client will have a very fast link so this is not +very important to support this feature in a client implementation, still +if an application needs to issue a very large number of commands in short +time to use pipelining can be much faster.<br/><br/> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/QuitCommand.html b/doc/QuitCommand.html new file mode 100644 index 000000000..c1508dce3 --- /dev/null +++ b/doc/QuitCommand.html @@ -0,0 +1,38 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>QuitCommand: Contents</b><br> <a href="#Quit">Quit</a><br> <a href="#Return value">Return value</a> + </div> + + <h1 class="wikiname">QuitCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="Quit">Quit</a></h1><blockquote>Ask the server to silently close the connection.</blockquote> +<h2><a name="Return value">Return value</a></h2>None. The connection is closed as soon as the QUIT command is received. + + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/README.html b/doc/README.html new file mode 100644 index 000000000..402038d7f --- /dev/null +++ b/doc/README.html @@ -0,0 +1,109 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>README: Contents</b><br> <a href="#Introduction">Introduction</a><br> <a href="#Beyond key-value databases">Beyond key-value databases</a><br> <a href="#What are the differences between Redis and Memcached?">What are the differences between Redis and Memcached?</a><br> <a href="#What are the differences between Redis and Tokyo Cabinet / Tyrant?">What are the differences between Redis and Tokyo Cabinet / Tyrant?</a><br> <a href="#Does Redis support locking?">Does Redis support locking?</a><br> <a href="#Multiple databases support">Multiple databases support</a><br> <a href="#Redis Data Types">Redis Data Types</a><br> <a href="#Implementation Details">Implementation Details</a><br> <a href="#Redis Tutorial">Redis Tutorial</a><br> <a href="#License">License</a><br> <a href="#Credits">Credits</a> + </div> + + <h1 class="wikiname">README</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="Introduction">Introduction</a></h1>Redis is a database. To be more specific redis is a very simple database +implementing a dictionary where keys are associated with values. For example +I can set the key "surname_1992" to the string "Smith".<br/><br/>Redis takes the whole dataset in memory, but the dataset is persistent +since from time to time Redis writes a dump of the dataset on disk asynchronously. The dump is loaded every time the server is restarted. This means that if a system crash occurs the last few queries can get lost (that is acceptable in many applications), so we supported master-slave replication from the early days.<h1><a name="Beyond key-value databases">Beyond key-value databases</a></h1>In most key-value databases keys and values are simple strings. In Redis keys are just strings too, but the associated values can be Strings, Lists and Sets, and there are commands to perform complex atomic operations against this data types, so you can think at Redis as a data structures server.<br/><br/>For example you can append elements to a list stored at the key "mylist" using the LPUSH or RPUSH operation in O(1). Later you'll be able to get a range of elements with LRANGE or trim the list with LTRIM. Sets are very flexible too, it is possible to add and remove elements from Sets (unsorted collections of strings), and then ask for server-side intersection of Sets.<br/><br/>All this features, the support for sorting Lists and Sets, allow to use Redis as the sole DB for your scalable application without the need of any relational database. <a href="TwitterAlikeExample.html">We wrote a simple Twitter clone in PHP + Redis</a> to show a real world example, the link points to an article explaining the design and internals in very simple words.<h1><a name="What are the differences between Redis and Memcached?">What are the differences between Redis and Memcached?</a></h1>In the following ways:<br/><br/><ul><li> Memcached is not persistent, it just holds everything in memory without saving since its main goal is to be used as a cache. Redis instead can be used as the main DB for the application. We <a href="TwitterAlikeExample.html">wrote a simple Twitter clone</a> using only Redis as database.</li></ul> +<ul><li> Like memcached Redis uses a key-value model, but while keys can just be strings, values in Redis can be lists and sets, and complex operations like intersections, set/get n-th element of lists, pop/push of elements, can be performed against sets and lists. It is possible to use lists as message queues.</li></ul> +<h1><a name="What are the differences between Redis and Tokyo Cabinet / Tyrant?">What are the differences between Redis and Tokyo Cabinet / Tyrant?</a></h1>Redis and Tokyo can be used for the same applications, but actually they are <b>ery</b> different beasts:<br/><br/><ul><li> Tokyo is purely key-value, everything beyond key-value storing of strings is delegated to an embedded Lua interpreter. AFAIK there is no way to guarantee atomicity of operations like pushing into a list, and every time you want to have data structures inside a Tokyo key you have to perform some kind of object serialization/de-serialization.</li></ul> +<ul><li> Tokyo stores data on disk, synchronously, this means you can have datasets bigger than memory, but that under load, like every kind of process that relay on the disk I/O for speed, the performances may start to degrade. With Redis you don't have this problems but you have another problem: the dataset in every single server must fit in your memory.</li></ul> +<ul><li> Redis is generally an higher level beast in the operations supported. Things like SORTing, Server-side set-intersections, can't be done with Tokyo. But Redis is not an on-disk DB engine like Tokyo: the latter can be used as a fast DB engine in your C project without the networking overhead just linking to the library. Still remember that in many scalable applications you need multiple servers talking with multiple servers, so the server-client model is almost always needed.</li></ul> +<h1><a name="Does Redis support locking?">Does Redis support locking?</a></h1>No, the idea is to provide atomic primitives in order to make the programmer +able to use redis with locking free algorithms. For example imagine you have +10 computers and 1 redis server. You want to count words in a very large text. +This large text is split among the 10 computers, every computer will process +its part and use Redis's INCR command to atomically increment a counter +for every occurrence of the word found.<br/><br/>INCR/DECR are not the only atomic primitives, there are others like PUSH/POP +on lists, POP RANDOM KEY operations, UPDATE and so on. For example you can +use Redis like a Tuple Space (<a href="http://en.wikipedia.org/wiki/Tuple_space" target="_blank">http://en.wikipedia.org/wiki/Tuple_space</a>) in +order to implement distributed algorithms.<br/><br/>(News: locking with key-granularity is now planned)<h1><a name="Multiple databases support">Multiple databases support</a></h1>Another synchronization primitive is the support for multiple DBs. By default DB 0 is selected for every new connection, but using the SELECT command it is possible to select a different database. The MOVE operation can move an item from one DB to another atomically. This can be used as a base for locking free algorithms together with the 'RANDOMKEY' or 'POPRANDOMKEY' commands.<h1><a name="Redis Data Types">Redis Data Types</a></h1>Redis supports the following three data types as values:<br/><br/><ul><li> Strings: just any sequence of bytes. Redis strings are binary safe so they can not just hold text, but images, compressed data and everything else.</li><li> Lists: lists of strings, with support for operations like append a new string on head, on tail, list length, obtain a range of elements, truncate the list to a given length, sort the list, and so on.</li><li> Sets: an unsorted set of strings. It is possible to add or delete elements from a set, to perform set intersection, union, subtraction, and so on.</li></ul> +Values can be Strings, Lists or Sets. Keys can be a subset of strings not containing newlines ("\n") and spaces (" ").<br/><br/>Note that sometimes strings may hold numeric vaules that must be parsed by +Redis. An example is the INCR command that atomically increments the number +stored at the specified key. In this case Redis is able to handle integers +that can be stored inside a 'long long' type, that is a 64-bit signed integer.<h2><a name="Implementation Details">Implementation Details</a></h2>Strings are implemented as dynamically allocated strings of characters. +Lists are implemented as doubly linked lists with cached length. +Sets are implemented using hash tables that use chaining to resolve collisions.<h1><a name="Redis Tutorial">Redis Tutorial</a></h1>(note, you can skip this section if you are only interested in "formal" doc.)<br/><br/>Later in this document you can find detailed information about Redis commands, +the protocol specification, and so on. This kind of documentation is useful +but... if you are new to Redis it is also BORING! The Redis protocol is designed +so that is both pretty efficient to be parsed by computers, but simple enough +to be used by humans just poking around with the 'telnet' command, so this +section will show to the reader how to play a bit with Redis to get an initial +feeling about it, and how it works.<br/><br/>To start just compile redis with 'make' and start it with './redis-server'. +The server will start and log stuff on the standard output, if you want +it to log more edit redis.conf, set the loglevel to debug, and restart it.<br/><br/>You can specify a configuration file as unique parameter:<br/><br/><blockquote>./redis-server /etc/redis.conf</blockquote> +This is NOT required. The server will start even without a configuration file +using a default built-in configuration.<br/><br/>Now let's try to set a key to a given value:<br/><br/><pre class="codeblock python" name="code"> +$ telnet localhost 6379 +Trying 127.0.0.1... +Connected to localhost. +Escape character is '^]'. +SET foo 3 +bar ++OK +</pre>The first line we sent to the server is "set foo 3". This means "set the key +foo with the following three bytes I'll send you". The following line is +the "bar" string, that is, the three bytes. So the effect is to set the +key "foo" to the value "bar". Very simple!<br/><br/>(note that you can send commands in lowercase and it will work anyway, +commands are not case sensitive)<br/><br/>Note that after the first and the second line we sent to the server there +is a newline at the end. The server expects commands terminated by "\r\n" +and sequence of bytes terminated by "\r\n". This is a minimal overhead from +the point of view of both the server and client but allows us to play with +Redis with the telnet command easily.<br/><br/>The last line of the chat between server and client is "+OK". This means +our key was added without problems. Actually SET can never fail but +the "+OK" sent lets us know that the server received everything and +the command was actually executed.<br/><br/>Let's try to get the key content now:<br/><br/><pre class="codeblock python python" name="code"> +GET foo +3 +bar +</pre>Ok that's very similar to 'set', just the other way around. We sent "get foo", +the server replied with a first line that is just a number of bytes the value +stored at key contained, followed by the actual bytes. Again "\r\n" are appended +both to the bytes count and the actual data.<br/><br/>What about requesting a non existing key?<br/><br/><pre class="codeblock python python python" name="code"> +GET blabla +nil +</pre>When the key does not exist instead of the length just the "nil" string is sent. +Another way to check if a given key exists or not is indeed the EXISTS command:<br/><br/><pre class="codeblock python python python python" name="code"> +EXISTS nokey +0 +EXISTS foo +1 +</pre>As you can see the server replied '0' the first time since 'nokey' does not +exist, and '1' for 'foo', a key that actually exists.<br/><br/>Ok... now you know the basics, read the <a href="CommandReference.html">REDIS COMMAND REFERENCE</a> section to +learn all the commands supported by Redis and the <a href="ProtocolSpecification.html">PROTOCOL SPECIFICATION</a> +section for more details about the protocol used if you plan to implement one +for a language missing a decent client implementation.<h1><a name="License">License</a></h1>Redis is released under the BSD license. See the COPYING file for more information.<h1><a name="Credits">Credits</a></h1>Redis is written and maintained by Salvatore Sanfilippo, Aka 'antirez'.<br/><br/>Enjoy, +antirez + + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/RandomkeyCommand.html b/doc/RandomkeyCommand.html new file mode 100644 index 000000000..8714f4c68 --- /dev/null +++ b/doc/RandomkeyCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>RandomkeyCommand: Contents</b><br> <a href="#RANDOMKEY">RANDOMKEY</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">RandomkeyCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="RANDOMKEY">RANDOMKEY</a></h1> +<i>Time complexity: O(1)</i><blockquote>Return a randomly selected key from the currently selected DB.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Singe line reply</a>, specifically the randomly selected key or an empty string is the database is empty.<h2><a name="See also">See also</a></h2> +<ul><li> <a href="KeysCommand.html">KEYS</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/RenameCommand.html b/doc/RenameCommand.html new file mode 100644 index 000000000..1ed0d9e10 --- /dev/null +++ b/doc/RenameCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>RenameCommand: Contents</b><br> <a href="#RENAME _oldkey_ _newkey_">RENAME _oldkey_ _newkey_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">RenameCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="RENAME _oldkey_ _newkey_">RENAME _oldkey_ _newkey_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Atomically renames the key <i>oldkey</i> to <i>newkey</i>. If the source anddestination name are the same an error is returned. If <i>newkey</i>already exists it is overwritten.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code repy</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="RenamenxCommand.html">RENAMENX</a> if you don't want overwrite the destionation key if it exists.</li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/RenamenxCommand.html b/doc/RenamenxCommand.html new file mode 100644 index 000000000..232cb65d1 --- /dev/null +++ b/doc/RenamenxCommand.html @@ -0,0 +1,44 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>RenamenxCommand: Contents</b><br> <a href="#RENAMENX _oldkey_ _newkey_">RENAMENX _oldkey_ _newkey_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">RenamenxCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="RENAMENX _oldkey_ _newkey_">RENAMENX _oldkey_ _newkey_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Rename <i>oldkey</i> into <i>newkey</i> but fails if the destination key <i>newkey</i> already exists.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +1 if the key was renamed +0 if the target key already exist +-1 if the source key does not exist +-3 if source and destination keys are the same +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="RenameCommand.html">RENAME</a> is like RENAMENX but overwrite existing destionation key.</li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/ReplyTypes.html b/doc/ReplyTypes.html new file mode 100644 index 000000000..18b4a640d --- /dev/null +++ b/doc/ReplyTypes.html @@ -0,0 +1,44 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>ReplyTypes: Contents</b><br> <a href="#Redis Reply Types">Redis Reply Types</a><br> <a href="#Status code reply">Status code reply</a><br> <a href="#Integer reply">Integer reply</a><br> <a href="#Bulk reply">Bulk reply</a><br> <a href="#Multi bulk reply">Multi bulk reply</a> + </div> + + <h1 class="wikiname">ReplyTypes</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="Redis Reply Types">Redis Reply Types</a></h1>Redis commands can reply to the client with four different kind of replies, you can find the protocol level specification of this replies in the <a href="ProtocolSpecification.html">Redis Protocol Specification</a>. This page is instead an higher level description of the four types of replies from the point of view of the final user.<h1><a name="Status code reply">Status code reply</a></h1> +Status code replies are in the form of a <b>+OK</b> from the server, or a <b>-ERR</b> followed by an error string. At the protocol level this replies are sent as a single line. Client libraries should return <i>true</i> on <b>OK</b>, and should raise an exception in form of an error that stops the execution of the program on <b>ERR</b> replies from server, because this kind of replies are used by operations that usually fails because of a programming error, an inconsistent DB, and so on.<h1><a name="Integer reply">Integer reply</a></h1> +At protocol level integer replies are single line replies in form of a decimal singed number. Redis commands returning <i>true</i> or <i>false</i> will use an integer reply and "1" and "0" as replies. A negative value in an integer reply is used to signal an error by all the commands, with the exception of <a href="IncrCommand.html">INCR</a>/<a href="IncrCommand.html">INCRBY</a>/<a href="IncrCommand.html">DECR</a>/<a href="IncrCommand.html">DECRBY</a> where negative return values are allowed (this command never fails).<br/><br/>All the integer replies using negative values to return errors will use the same values to signal the same errors: +<b> -1 key not found +</b> -2 key contains a value of the wrong type +<b> -3 source object and destination object are the same +</b> -4 out of range argument<br/><br/>Integer replies are usually passed by client libraries as integer values. On negative integer reply an exception should be raised (excluding the INCR family commands).<h1><a name="Bulk reply">Bulk reply</a></h1> +A bulk reply is a binary-safe reply that is used to return a single string value (string is not limited to alphanumerical strings, it may contain binary data of any kind). Client libraries will usually return a string as return value of Redis commands returning bulk replies. There is a special bulk reply that signal that the element does not exist. When this happens the client library should return 'nil', 'false', or some other special element that can be distinguished by an empty string.<h1><a name="Multi bulk reply">Multi bulk reply</a></h1> +While a bulk reply returns a single string value, multi bulk replies are used to return multiple values: lists, sets, and so on. Elements of a bulk reply can be missing (-1 length count at protocol level). Client libraries should return 'nil' or 'false' in order to make this elements distinguishable from empty strings. Client libraries should return multi bulk replies that are about ordered elements like list ranges as lists, and bulk replies about sets as hashes. + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/RpushCommand.html b/doc/RpushCommand.html new file mode 100644 index 000000000..e22c8b577 --- /dev/null +++ b/doc/RpushCommand.html @@ -0,0 +1,40 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>RpushCommand: Contents</b><br> <a href="#RPUSH _key_ _string_">RPUSH _key_ _string_</a><br> <a href="#LPUSH _key_ _string_">LPUSH _key_ _string_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">RpushCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h3><a name="RPUSH _key_ _string_">RPUSH _key_ _string_</a></h3> +<h3><a name="LPUSH _key_ _string_">LPUSH _key_ _string_</a></h3> +<i>Time complexity: O(1)</i><blockquote>Add the <i>string</i> value to the head (RPUSH) or tail (LPUSH) of the liststored at <i>key</i>. If the key does not exist an empty list is created just beforethe append operation. If the key exists but is not a List an erroris returned.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="LlenCommand.html">LLEN</a></li><li> <a href="LrangeCommand.html">LRANGE</a></li><li> <a href="LtrimCommand.html">LTRIM</a></li><li> <a href="LdelCommand.html">LDEL</a></li><li> <a href="LindexCommand.html">LINDEX</a></li><li> <a href="LsetCommand.html">LSET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SaddCommand.html b/doc/SaddCommand.html new file mode 100644 index 000000000..ed3258ca1 --- /dev/null +++ b/doc/SaddCommand.html @@ -0,0 +1,43 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SaddCommand: Contents</b><br> <a href="#SADD _key_ _member_">SADD _key_ _member_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SaddCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SADD _key_ _member_">SADD _key_ _member_</a></h1> +<i>Time complexity O(1)</i><blockquote>Add the specified <i>member</i> to the set value stored at <i>key</i>. If <i>member</i>is already a member of the set no operation is performed. If <i>key</i>does not exist a new set with the specified <i>member</i> as sole member iscrated. If the key exists but does not hold a set value an error isreturned.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +1 if the new element was added +0 if the new element was already a member of the set +-2 if the key contains a non set value +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SremCommand.html">SREM</a></li><li> <a href="SismemberCommand.html">SISMEMBER</a></li><li> <a href="ScardCommand.html">SCARD</a></li><li> <a href="SmembersCommand.html">SMEMBERS</a></li><li> <a href="SinterCommand.html">SINTER</a></li><li> <a href="SinterstoreCommand.html">SINTERSTORE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SaveCommand.html b/doc/SaveCommand.html new file mode 100644 index 000000000..3c4c37145 --- /dev/null +++ b/doc/SaveCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SaveCommand: Contents</b><br> <a href="#SAVE">SAVE</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SaveCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h3><a name="SAVE">SAVE</a></h3> +<blockquote>Save the DB on disk. The server hangs while the saving is notcompleted, no connection is served in the meanwhile. An OK codeis returned when the DB was fully stored in disk.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="BgsaveCommand.html">BGSAVE</a></li><li> <a href="ShutdownCommand.html">SHUTDOWN</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/ScardCommand.html b/doc/ScardCommand.html new file mode 100644 index 000000000..d85be9db5 --- /dev/null +++ b/doc/ScardCommand.html @@ -0,0 +1,42 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>ScardCommand: Contents</b><br> <a href="#SCARD _key_">SCARD _key_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">ScardCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SCARD _key_">SCARD _key_</a></h1> +<i>Time complexity O(1)</i><blockquote>Return the set cardinality (number of elements). If the <i>key</i> does notexist 0 is returned, like for empty sets. If the <i>key</i> does not holda set value -1 is returned. Client libraries should raise an errorwhen -1 is returned instead to pass the value to the caller.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +the cardinality (number of elements) of the set as an integer `>=` 0 if the operation succeeded +-2 if the specified key does not hold a set value +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SremCommand.html">SREM</a></li><li> <a href="SismemberCommand.html">SISMEMBER</a></li><li> <a href="ScardCommand.html">SCARD</a></li><li> <a href="SmembersCommand.html">SMEMBERS</a></li><li> <a href="SinterCommand.html">SINTER</a></li><li> <a href="SinterstoreCommand.html">SINTERSTORE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SelectCommand.html b/doc/SelectCommand.html new file mode 100644 index 000000000..11c4b0502 --- /dev/null +++ b/doc/SelectCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SelectCommand: Contents</b><br> <a href="#SELECT _index_">SELECT _index_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SelectCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SELECT _index_">SELECT _index_</a></h1> +<blockquote>Select the DB with having the specified zero-based numeric index.For default every new client connection is automatically selectedto DB 0.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="FlushdbCommand.html">FLUSHDB</a></li><li> <a href="MoveCommand.html">MOVE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SetCommand.html b/doc/SetCommand.html new file mode 100644 index 000000000..63c51f460 --- /dev/null +++ b/doc/SetCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SetCommand: Contents</b><br> <a href="#SET _key_ _value_">SET _key_ _value_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SetCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SET _key_ _value_">SET _key_ _value_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Set the string <i>value</i> as value of the <i>key</i>.The string can't be longer than 1073741824 bytes (1 GB).</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SetnxCommand.html">SETNX</a> is like SET but don't perform the operation if the target key already exists.</li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SetnxCommand.html b/doc/SetnxCommand.html new file mode 100644 index 000000000..15a6c0e24 --- /dev/null +++ b/doc/SetnxCommand.html @@ -0,0 +1,42 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SetnxCommand: Contents</b><br> <a href="#SETNX _key_ _value_">SETNX _key_ _value_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SetnxCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SETNX _key_ _value_">SETNX _key_ _value_</a></h1> +<i>Time complexity: O(1)</i><blockquote>SETNX works exactly like <a href="SetCommand.html">SET</a> with the only difference thatif the key already exists no operation is performed.SETNX actually means "SET if Not eXists".</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +1 if the key was set +0 if the key was not set +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SetCommand.html">SET</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/ShutdownCommand.html b/doc/ShutdownCommand.html new file mode 100644 index 000000000..ce77ae971 --- /dev/null +++ b/doc/ShutdownCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>ShutdownCommand: Contents</b><br> <a href="#SHUTDOWN">SHUTDOWN</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">ShutdownCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SHUTDOWN">SHUTDOWN</a></h1> +<blockquote>Stop all the clients, save the DB, then quit the server. This commandsmakes sure that the DB is switched off without the lost of any data.This is not guaranteed if the client uses simply "SAVE" and then"QUIT" because other clients may alter the DB data between the twocommands.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a> on error. On success nothing is returned since the server quits and the connection is closed.<h2><a name="See also">See also</a></h2> +<ul><li> <a href="SaveCommand.html">SAVE</a></li><li> <a href="BgsaveCommand.html">BGSAVE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SinterCommand.html b/doc/SinterCommand.html new file mode 100644 index 000000000..22d6acf59 --- /dev/null +++ b/doc/SinterCommand.html @@ -0,0 +1,40 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SinterCommand: Contents</b><br> <a href="#SINTER _key1_ _key2_ ... _keyN_">SINTER _key1_ _key2_ ... _keyN_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SinterCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SINTER _key1_ _key2_ ... _keyN_">SINTER _key1_ _key2_ ... _keyN_</a></h1> +<i>Time complexity O(N<b>M) worst case where N is the cardinality of the smallest set and M the number of sets_<br/><br/><blockquote>Return the members of a set resulting from the intersection of all thesets hold at the specified keys. Like in LRANGE the result is sent tothe client as a multi-bulk reply (see the protocol specification formore information). If just a single key is specified, then this commandproduces the same result as SELEMENTS. Actually SELEMENTS is just syntaxsugar for SINTERSECT.</blockquote> +<blockquote>If at least one of the specified keys does not exist or does not holda set value an error is returned.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Multi bulk reply</a>, specifically the list of common elements.<h2><a name="See also">See also</a></h2> +<blockquote>* <a href="SremCommand.html">SREM</a>* <a href="SismemberCommand.html">SISMEMBER</a>* <a href="ScardCommand.html">SCARD</a>* <a href="SmembersCommand.html">SMEMBERS</a>* <a href="SinterCommand.html">SINTER</a>* <a href="SinterstoreCommand.html">SINTERSTORE</a></blockquote></b></i> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SinterstoreCommand.html b/doc/SinterstoreCommand.html new file mode 100644 index 000000000..02757ccf3 --- /dev/null +++ b/doc/SinterstoreCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SinterstoreCommand: Contents</b><br> <a href="#SINTERSTORE _dstkey_ _key1_ _key2_ ... _keyN_">SINTERSTORE _dstkey_ _key1_ _key2_ ... _keyN_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SinterstoreCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SINTERSTORE _dstkey_ _key1_ _key2_ ... _keyN_">SINTERSTORE _dstkey_ _key1_ _key2_ ... _keyN_</a></h1> +<i>Time complexity O(N<b>M) worst case where N is the cardinality of the smallest set and M the number of sets_<br/><br/><blockquote>This commnad works exactly like SINTER but instead of being returned the resulting set is sotred as _dstkey_.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Status code reply</a><h2><a name="See also">See also</a></h2> +<blockquote>* <a href="SremCommand.html">SREM</a>* <a href="SismemberCommand.html">SISMEMBER</a>* <a href="ScardCommand.html">SCARD</a>* <a href="SmembersCommand.html">SMEMBERS</a>* <a href="SinterCommand.html">SINTER</a>* <a href="SinterstoreCommand.html">SINTERSTORE</a></blockquote></b></i> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SismemberCommand.html b/doc/SismemberCommand.html new file mode 100644 index 000000000..63516d02d --- /dev/null +++ b/doc/SismemberCommand.html @@ -0,0 +1,43 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SismemberCommand: Contents</b><br> <a href="#SISMEMBER _key_ _member_">SISMEMBER _key_ _member_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SismemberCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SISMEMBER _key_ _member_">SISMEMBER _key_ _member_</a></h1> +<i>Time complexity O(1)</i><blockquote>Return 1 if <i>member</i> is a member of the set stored at <i>key</i>, otherwise0 is returned. On error a negative value is returned. Client librariesshould raise an error when a negative value is returned instead to passthe value to the caller.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +1 if the element is a member of the set +0 if the element is not a member of the set OR if the key does not exist +-2 if the key does not hold a set value +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SremCommand.html">SREM</a></li><li> <a href="SismemberCommand.html">SISMEMBER</a></li><li> <a href="ScardCommand.html">SCARD</a></li><li> <a href="SmembersCommand.html">SMEMBERS</a></li><li> <a href="SinterCommand.html">SINTER</a></li><li> <a href="SinterstoreCommand.html">SINTERSTORE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SmembersCommand.html b/doc/SmembersCommand.html new file mode 100644 index 000000000..52bdcbc4f --- /dev/null +++ b/doc/SmembersCommand.html @@ -0,0 +1,39 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SmembersCommand: Contents</b><br> <a href="#SMEMBERS _key_">SMEMBERS _key_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SmembersCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SMEMBERS _key_">SMEMBERS _key_</a></h1> +<i>Time complexity O(N)</i><blockquote>Return all the members (elements) of the set value stored at <i>key</i>. Thisis just syntax glue for <a href="SintersectCommand.html">SINTERSECT</a>.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Multi bulk reply</a><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SremCommand.html">SREM</a></li><li> <a href="SismemberCommand.html">SISMEMBER</a></li><li> <a href="ScardCommand.html">SCARD</a></li><li> <a href="SmembersCommand.html">SMEMBERS</a></li><li> <a href="SinterCommand.html">SINTER</a></li><li> <a href="SinterstoreCommand.html">SINTERSTORE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SortCommand.html b/doc/SortCommand.html new file mode 100644 index 000000000..3d88e4012 --- /dev/null +++ b/doc/SortCommand.html @@ -0,0 +1,60 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SortCommand: Contents</b><br> <a href="#SORT _key_ BY _pattern_ LIMIT _start_ _end_ GET _pattern_ ASC|DESC ALPHA">SORT _key_ BY _pattern_ LIMIT _start_ _end_ GET _pattern_ ASC|DESC ALPHA</a><br> <a href="#Return value">Return value</a><br> <a href="#See Also">See Also</a> + </div> + + <h1 class="wikiname">SortCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SORT _key_ BY _pattern_ LIMIT _start_ _end_ GET _pattern_ ASC|DESC ALPHA">SORT _key_ BY _pattern_ LIMIT _start_ _end_ GET _pattern_ ASC|DESC ALPHA</a></h1> +<blockquote>Sort the elements contained in the List or Set value at <i>key</i>. By defaultsorting is numeric with elements being compared as double precisionfloating point numbers. This is the simplest form of SORT.</blockquote> +<pre class="codeblock python" name="code"> +SORT mylist +</pre><blockquote>Assuming mylist contains a list of numbers, the return value will bethe list of numbers ordered from the smallest to the bigger number.In order to get the sorting in reverse order use DESC:</blockquote> +<pre class="codeblock python python" name="code"> +SORT mylist DESC +</pre><blockquote>ASC is also supported but it's the default so you don't really need it.If you want to sort lexicographically use ALPHA. Note that Redis isutf-8 aware assuming you set the right value for the LC_COLLATEenvironment variable.</blockquote> +<blockquote>Sort is able to limit the number of results using the LIMIT option:</blockquote> +<pre class="codeblock python python python" name="code"> +SORT mylist LIMIT 0 10 +</pre><blockquote>In the above example SORT will return only 10 elements, starting fromthe first one (star is zero-based). Almost all the sort options canbe mixed together. For example:</blockquote> +<pre class="codeblock python python python python" name="code"> +SORT mylist LIMIT 0 10 ALPHA DESC +</pre><blockquote>Will sort <i>mylist</i> lexicographically, in descending order, returning onlythe first 10 elements.</blockquote> +<blockquote>Sometimes you want to sort elements using external keys as weights tocompare instead to compare the actual List or Set elements. For examplethe list <i>mylist</i> may contain the elements 1, 2, 3, 4, that are justthe unique IDs of objects stored at object_1, object_2, object_3and object_4, while the keys weight_1, weight_2, weight_3 and weight_4can contain weights we want to use to sort the list of objectsidentifiers. We can use the following command:</blockquote> +<pre class="codeblock python python python python python" name="code"> +SORT mylist BY weight_* +</pre><blockquote>the BY option takes a pattern (<code name="code" class="python">weight_*</code> in our example) that is usedin order to generate the key names of the weights used for sorting.Weight key names are obtained substituting the first occurrence of <code name="code" class="python">*</code>with the actual value of the elements on the list (1,2,3,4 in our example).</blockquote> +<blockquote>Still our previous example will return just the sorted IDs. Often it isneeded to get the actual objects sorted (object_1, ..., object_4 in theexample). We can do it with the following command:</blockquote> +<pre class="codeblock python python python python python python" name="code"> +SORT mylist BY weight_* GET object_* +</pre><blockquote>Note that GET can be used multiple times in order to get more keys forevery element of the original List or Set sorted.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Multi bulk reply</a>, specifically a list of sorted elements.<h2><a name="See Also">See Also</a></h2> +<ul><li> <a href="SinterCommand.html">SINTER</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/SremCommand.html b/doc/SremCommand.html new file mode 100644 index 000000000..6219e92c0 --- /dev/null +++ b/doc/SremCommand.html @@ -0,0 +1,43 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>SremCommand: Contents</b><br> <a href="#SREM _key_ _member_">SREM _key_ _member_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">SremCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="SREM _key_ _member_">SREM _key_ _member_</a></h1> +<i>Time complexity O(1)</i><blockquote>Remove the specified <i>member</i> from the set value stored at <i>key</i>. If_member_ was not a member of the set no operation is performed. If <i>key</i>does not exist or does not hold a set value an error is returned.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Integer reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +1 if the new element was removed +0 if the new element was not a member of the set +-2 if the key does not hold a set value +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="SremCommand.html">SREM</a></li><li> <a href="SismemberCommand.html">SISMEMBER</a></li><li> <a href="ScardCommand.html">SCARD</a></li><li> <a href="SmembersCommand.html">SMEMBERS</a></li><li> <a href="SinterCommand.html">SINTER</a></li><li> <a href="SinterstoreCommand.html">SINTERSTORE</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/TemplateCommand.html b/doc/TemplateCommand.html new file mode 100644 index 000000000..7286836ed --- /dev/null +++ b/doc/TemplateCommand.html @@ -0,0 +1,38 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>TemplateCommand: Contents</b><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">TemplateCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">ReplyTypes</a><h2><a name="See also">See also</a></h2> +<ul><li> []</li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/TwitterAlikeExample.html b/doc/TwitterAlikeExample.html new file mode 100644 index 000000000..adb9bbaaf --- /dev/null +++ b/doc/TwitterAlikeExample.html @@ -0,0 +1,252 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>TwitterAlikeExample: Contents</b><br> <a href="#A case study: Design and implementation of a simple Twitter clone using only the Redis key-value store as database and PHP">A case study: Design and implementation of a simple Twitter clone using only the Redis key-value store as database and PHP</a><br> <a href="#Key-value stores basics">Key-value stores basics</a><br> <a href="#Atomic operations">Atomic operations</a><br> <a href="#Beyond key-value stores">Beyond key-value stores</a><br> <a href="#The set data type">The set data type</a><br> <a href="#Prerequisites">Prerequisites</a><br> <a href="#Data layout">Data layout</a><br> <a href="#Following, followers and updates">Following, followers and updates</a><br> <a href="#Authentication">Authentication</a><br> <a href="#Updates">Updates</a><br> <a href="#Paginating updates">Paginating updates</a><br> <a href="#Following users">Following users</a><br> <a href="#Making it horizontally scalable">Making it horizontally scalable</a><br> <a href="#Hashing the key">Hashing the key</a><br> <a href="#Special keys">Special keys</a> + </div> + + <h1 class="wikiname">TwitterAlikeExample</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="A case study: Design and implementation of a simple Twitter clone using only the Redis key-value store as database and PHP">A case study: Design and implementation of a simple Twitter clone using only the Redis key-value store as database and PHP</a></h1>In this article I'll explain the design and the implementation of a <a href="http://retwis.antirez.com" target="_blank">simple clone of Twitter</a> written using PHP and <a href="http://code.google.com/p/redis/" target="_blank">Redis</a> as only database. The programming community uses to look at key-value stores like special databases that can't be used as drop in replacement for a relational database for the development of web applications. This article will try to prove the contrary.<br/><br/>Our Twitter clone, <a href="http://retwis.antirez.com" target="_blank">called Retwis</a>, is structurally simple, has very good performances, and can be distributed among N web servers and M Redis servers with very little efforts. You can find the source code <a href="http://code.google.com/p/redis/downloads/list" target="_blank">here</a>.<br/><br/>We use PHP for the example since it can be read by everybody. The same (or... much better) results can be obtained using Ruby, Python, Erlang, and so on. +<h1><a name="Key-value stores basics">Key-value stores basics</a></h1> +The essence of a key-value store is the ability to store some data, called <i>value</i>, inside a key. This data can later be retrieved only if we know the exact key used to store it. There is no way to search something by value. So for example I can use the command SET to store the value <b>bar</b> at key <b>foo</b>:<br/><br/><pre class="codeblock python" name="code"> +SET foo bar +</pre>Redis will store our data permanently, so we can later ask for "<i>What is the value stored at key foo?</i>" and Redis will reply with <b>bar</b>:<br/><br/><pre class="codeblock python python" name="code"> +GET foo => bar +</pre>Other common operations provided by key-value stores are DEL used to delete a given key, and the associated value, SET-if-not-exists (called SETNX on Redis) that sets a key only if it does not already exist, and INCR that is able to atomically increment a number stored at a given key:<br/><br/><pre class="codeblock python python python" name="code"> +SET foo 10 +INCR foo => 11 +INCR foo => 12 +INCR foo => 13 +</pre><h2><a name="Atomic operations">Atomic operations</a></h2> +So far it should be pretty simple, but there is something special about INCR. Think about this, why to provide such an operation if we can do it ourself with a bit of code? After all it is as simple as:<br/><br/><pre class="codeblock python python python python" name="code"> +x = GET foo +x = x + 1 +SET foo x +</pre>The problem is that doing the increment this way will work as long as there is only a client working with the value <i>x</i> at a time. See what happens if two computers are accessing this data at the same time:<br/><br/><pre class="codeblock python python python python python" name="code"> +x = GET foo (yields 10) +y = GET foo (yields 10) +x = x + 1 (x is now 11) +y = y + 1 (y is now 11) +SET foo x (foo is now 11) +SET foo y (foo is now 11) +</pre>Something is wrong with that! We incremented the value two times, but instead to go from 10 to 12 our key holds 11. This is because the INCR operation done with <code name="code" class="python">GET / increment / SET</code> <b>is not an atomic operation</b>. Instead the INCR provided by Redis, Memcached, ..., are atomic implementations, the server will take care to protect the get-increment-set for all the time needed to complete in order to prevent simultaneous accesses.<br/><br/>What makes Redis different from other key-value stores is that it provides more operations similar to INCR that can be used together to model complex problems. This is why you can use Redis to write whole web applications without using an SQL database and without to get mad. +<h2><a name="Beyond key-value stores">Beyond key-value stores</a></h2> +In this section we will see what Redis features we need to build our Twitter clone. The first thing to know is that Redis values can be more than strings. Redis supports Lists and Sets as values, and there are atomic operations to operate against this more advanced values so we are safe even with multiple accesses against the same key. Let's start from Lists:<br/><br/><pre class="codeblock python python python python python python" name="code"> +LPUSH mylist a (now mylist holds one element list 'a') +LPUSH mylist b (now mylist holds 'b,a') +LPUSH mylist c (now mylist holds 'c,b,a') +</pre>LPUSH means <i>Left Push</i>, that is, add an element to the left (or to the head) of the list stored at <i>mylist</i>. If the key <i>mylist</i> does not exist it is automatically created by Redis as an empty list before the PUSH operation. As you can imagine, there is also the RPUSH operation that adds the element on the right of the list (on the tail).<br/><br/>This is very useful for our Twitter clone. Updates of users can be stored into a list stored at <code name="code" class="python">username:updates</code> for instance. There are operations to get data or information from Lists of course. For instance LRANGE returns a range of the list, or the whole list.<br/><br/><pre class="codeblock python python python python python python python" name="code"> +LRANGE mylist 0 1 => c,b +</pre>LRANGE uses zero-based indexes, that is the first element is 0, the second 1, and so on. The command aguments are <code name="code" class="python">LRANGE key first-index last-index</code>. The <i>last index</i> argument can be negative, with a special meaning: -1 is the last element of the list, -2 the penultimate, and so on. So in order to get the whole list we can use:<br/><br/><pre class="codeblock python python python python python python python python" name="code"> +LRANGE mylist 0 -1 => c,b,a +</pre>Other important operations are LLEN that returns the length of the list, and LTRIM that is like LRANGE but instead of returning the specified range <b>trims</b> the list, so it is like <i>Get range from mylist, Set this range as new value</i> but atomic. We will use only this List operations, but make sure to check the <a href="http://code.google.com/p/redis/wiki/README" target="_blank">Redis documentation</a> to discover all the List operations supported by Redis. +<h3><a name="The set data type">The set data type</a></h3> +There is more than Lists, Redis also supports Sets, that are unsorted collection of elements. It is possible to add, remove, and test for existence of members, and perform intersection between different Sets. Of course it is possible to ask for the list or the number of elements of a Set. Some example will make it more clear. Keep in mind that SADD is the <i>add to set</i> operation, SREM is the <i>remove from set</i> operation, <i>sismember</i> is the <i>test if it is a member</i> operation, and SINTER is <i>perform intersection</i> operation. Other operations are SCARD that is used to get the cardinality (the number of elements) of a Set, and SMEMBERS that will return all the members of a Set.<br/><br/><pre class="codeblock python python python python python python python python python" name="code"> +SADD myset a +SADD myset b +SADD myset foo +SADD myset bar +SCARD myset => 4 +SMEMBERS myset => bar,a,foo,b +</pre>Note that SMEMBERS does not return the elements in the same order we added them, since Sets are <b>unsorted</b> collections of elements. When you want to store the order it is better to use Lists instead. Some more operations against Sets:<br/><br/><pre class="codeblock python python python python python python python python python python" name="code"> +SADD mynewset b +SADD mynewset foo +SADD mynewset hello +SINTER myset mynewset => foo,b +</pre>SINTER can return the intersection between Sets but it is not limited to two sets, you may ask for intersection of 4,5 or 10000 Sets. Finally let's check how SISMEMBER works:<br/><br/><pre class="codeblock python python python python python python python python python python python" name="code"> +SISMEMBER myset foo => 1 +SISMEMBER myset notamember => 0 +</pre>Ok I think we are ready to start coding! +<h2><a name="Prerequisites">Prerequisites</a></h2> +If you didn't download it already please <a href="http://code.google.com/p/redis/wiki/README" target="_blank">grab the source code of Retwis</a>. It's a simple tar.gz file with a few of .php files inside. The implementation is very simple. You will find the PHP library client inside (redis.php) that is used to talk with the Redis server from PHP. This library was written by <a href="http://qix.it" target="_blank">Ludovico Magnocavallo</a> and you are free to reuse this in your own projects, but for updated version of the library please download the Redis distribution.<br/><br/>Another thing you probably want is a working Redis server. Just get the source, compile with make, and run with ./redis-server and you are done. No configuration is required at all in order to play with it or to run Retwis in your computer. +<h2><a name="Data layout">Data layout</a></h2> +Working with a relational database this is the stage were the database layout should be produced in form of tables, indexes, and so on. We don't have tables, so what should be designed? We need to identify what keys are needed to represent our objects and what kind of values this keys need to hold.<br/><br/>Let's start from Users. We need to represent this users of course, with the username, userid, password, followers and following users, and so on. The first question is, what should identify an user inside our system? The username can be a good idea since it is unique, but it is also too big, and we want to stay low on memory. So like if our DB was a relational one we can associate an unique ID to every user. Every other reference to this user will be done by id. That's very simple to do, because we have our atomic INCR operation! When we create a new user we can do something like this, assuming the user is callled "antirez":<br/><br/><pre class="codeblock python python python python python python python python python python python python" name="code"> +INCR global:nextUserId => 1000 +SET uid:1000:username antirez +SET uid:1000:password p1pp0 +</pre>We use the <i>global:nextUserId</i> key in order to always get an unique ID for every new user. Then we use this unique ID to populate all the other keys holding our user data. <b>This is a Design Pattern</b> with key-values stores! Keep it in mind. +Besides the fields already defined, we need some more stuff in order to fully define an User. For example sometimes it can be useful to be able to get the user ID from the username, so we set this key too:<br/><br/><pre class="codeblock python python python python python python python python python python python python python" name="code"> +SET username:antirez:uid 1000 +</pre>This may appear strange at first, but remember that we are only able to access data by key! It's not possible to tell Redis to return the key that holds a specific value. This is also <b>our strength</b>, this new paradigm is forcing us to organize the data so that everything is accessible by <i>primary key</i>, speaking with relational DBs language. +<h2><a name="Following, followers and updates">Following, followers and updates</a></h2> +There is another central need in our system. Every user has followers users and following users. We have a perfect data structure for this work! That is... Sets. So let's add this two new fields to our schema:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python" name="code"> +uid:1000:followers => Set of uids of all the followers users +uid:1000:following => Set of uids of all the following users +</pre>Another important thing we need is a place were we can add the updates to display in the user home page. We'll need to access this data in chronological order later, from the most recent update to the older ones, so the perfect kind of Value for this work is a List. Basically every new update will be LPUSHed in the user updates key, and thanks to LRANGE we can implement pagination and so on. Note that we use the words <i>updates</i> and <i>posts</i> interchangeably, since updates are actually "little posts" in some way.<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python" name="code"> +uid:1000:posts => a List of post ids, every new post is LPUSHed here. +</pre> +<h2><a name="Authentication">Authentication</a></h2> +Ok we have more or less everything about the user, but authentication. We'll handle authentication in a simple but robust way: we don't want to use PHP sessions or other things like this, our system must be ready in order to be distributed among different servers, so we'll take the whole state in our Redis database. So all we need is a random string to set as the cookie of an authenticated user, and a key that will tell us what is the user ID of the client holding such a random string. We need two keys in order to make this thing working in a robust way:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python" name="code"> +SET uid:1000:auth fea5e81ac8ca77622bed1c2132a021f9 +SET auth:fea5e81ac8ca77622bed1c2132a021f9 1000 +</pre>In order to authenticate an user we'll do this simple work (login.php): +<ul><li> Get the username and password via the login form</li><li> Check if the username:<code name="code" class="python"><username></code>:uid key actually exists</li><li> If it exists we have the user id, (i.e. 1000)</li><li> Check if uid:1000:password matches, if not, error message</li><li> Ok authenticated! Set "fea5e81ac8ca77622bed1c2132a021f9" (the value of uid:1000:auth) as "auth" cookie</li></ul> +This is the actual code:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python python" name="code"> +include("retwis.php"); + +# Form sanity checks +if (!gt("username") || !gt("password")) + goback("You need to enter both username and password to login."); + +# The form is ok, check if the username is available +$username = gt("username"); +$password = gt("password"); +$r = redisLink(); +$userid = $r->get("username:$username:id"); +if (!$userid) + goback("Wrong username or password"); +$realpassword = $r->get("uid:$userid:password"); +if ($realpassword != $password) + goback("Wrong useranme or password"); + +# Username / password OK, set the cookie and redirect to index.php +$authsecret = $r->get("uid:$userid:auth"); +setcookie("auth",$authsecret,time()+3600*24*365); +header("Location: index.php"); +</pre>This happens every time the users log in, but we also need a function isLoggedIn in order to check if a given user is already authenticated or not. These are the logical steps preformed by the <code name="code" class="python">isLoggedIn</code> function: +<ul><li> Get the "auth" cookie from the user. If there is no cookie, the user is not logged in, of course. Let's call the value of this cookie <code name="code" class="python"><authcookie></code></li><li> Check if auth:<code name="code" class="python"><authcookie></code> exists, and what the value (the user id) is (1000 in the exmple).</li><li> In order to be sure check that uid:1000:auth matches.</li><li> Ok the user is authenticated, and we loaded a bit of information in the $User global variable.</li></ul> +The code is simpler than the description, possibly:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python python python" name="code"> +function isLoggedIn() { + global $User, $_COOKIE; + + if (isset($User)) return true; + + if (isset($_COOKIE['auth'])) { + $r = redisLink(); + $authcookie = $_COOKIE['auth']; + if ($userid = $r->get("auth:$authcookie")) { + if ($r->get("uid:$userid:auth") != $authcookie) return false; + loadUserInfo($userid); + return true; + } + } + return false; +} + +function loadUserInfo($userid) { + global $User; + + $r = redisLink(); + $User['id'] = $userid; + $User['username'] = $r->get("uid:$userid:username"); + return true; +} +</pre><code name="code" class="python">loadUserInfo</code> as separated function is an overkill for our application, but it's a good template for a complex application. The only thing it's missing from all the authentication is the logout. What we do on logout? That's simple, we'll just change the random string in uid:1000:auth, remove the old auth:<code name="code" class="python"><oldauthstring></code> and add a new auth:<code name="code" class="python"><newauthstring></code>.<br/><br/><b>Important:</b> the logout procedure explains why we don't just authenticate the user after the lookup of auth:<code name="code" class="python"><randomstring></code>, but double check it against uid:1000:auth. The true authentication string is the latter, the auth:<code name="code" class="python"><randomstring></code> is just an authentication key that may even be volatile, or if there are bugs in the program or a script gets interrupted we may even end with multiple auth:<code name="code" class="python"><something></code> keys pointing to the same user id. The logout code is the following (logout.php):<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python python python python" name="code"> +include("retwis.php"); + +if (!isLoggedIn()) { + header("Location: index.php"); + exit; +} + +$r = redisLink(); +$newauthsecret = getrand(); +$userid = $User['id']; +$oldauthsecret = $r->get("uid:$userid:auth"); + +$r->set("uid:$userid:auth",$newauthsecret); +$r->set("auth:$newauthsecret",$userid); +$r->delete("auth:$oldauthsecret"); + +header("Location: index.php"); +</pre>That is just what we described and should be simple to undestand. +<h2><a name="Updates">Updates</a></h2> +Updates, also known as posts, are even simpler. In order to create a new post on the database we do something like this:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python python python python python" name="code"> +INCR global:nextPostId => 10343 +SET post:10343 "$owner_id|$time|I'm having fun with Retwis" +</pre>As you can se the user id and time of the post are stored directly inside the string, we don't need to lookup by time or user id in the example application so it is better to compact everything inside the post string.<br/><br/>After we create a post we obtain the post id. We need to LPUSH this post id in every user that's following the author of the post, and of course in the list of posts of the author. This is the file update.php that shows how this is performed:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python python python python python python" name="code"> +include("retwis.php"); + +if (!isLoggedIn() || !gt("status")) { + header("Location:index.php"); + exit; +} + +$r = redisLink(); +$postid = $r->incr("global:nextPostId"); +$status = str_replace("\n"," ",gt("status")); +$post = $User['id']."|".time()."|".$status; +$r->set("post:$postid",$post); +$followers = $r->smembers("uid:".$User['id'].":followers"); +if ($followers === false) $followers = Array(); +$followers[] = $User['id']; /* Add the post to our own posts too */ + +foreach($followers as $fid) { + $r->push("uid:$fid:posts",$postid,false); +} +# Push the post on the timeline, and trim the timeline to the +# newest 1000 elements. +$r->push("global:timeline",$postid,false); +$r->ltrim("global:timeline",0,1000); + +header("Location: index.php"); +</pre>The core of the function is the <code name="code" class="python">foreach</code>. We get using SMEMBERS all the followers of the current user, then the loop will LPUSH the post against the uid:<code name="code" class="python"><userid></code>:posts of every follower.<br/><br/>Note that we also maintain a timeline with all the posts. In order to do so what is needed is just to LPUSH the post against global:timeline. Let's face it, do you start thinking it was a bit strange to have to sort things added in chronological order using ORDER BY with SQL? I think so indeed. +<h2><a name="Paginating updates">Paginating updates</a></h2> +Now it should be pretty clear how we can user LRANGE in order to get ranges of posts, and render this posts on the screen. The code is simple:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python python python python python python python" name="code"> +function showPost($id) { + $r = redisLink(); + $postdata = $r->get("post:$id"); + if (!$postdata) return false; + + $aux = explode("|",$postdata); + $id = $aux[0]; + $time = $aux[1]; + $username = $r->get("uid:$id:username"); + $post = join(array_splice($aux,2,count($aux)-2),"|"); + $elapsed = strElapsed($time); + $userlink = "<a class=\"username\" href=\"profile.php?u=".urlencode($username)."\">".utf8entities($username)."</a>"; + + echo('<div class="post">'.$userlink.' '.utf8entities($post)."<br>"); + echo('<i>posted '.$elapsed.' ago via web</i></div>'); + return true; +} + +function showUserPosts($userid,$start,$count) { + $r = redisLink(); + $key = ($userid == -1) ? "global:timeline" : "uid:$userid:posts"; + $posts = $r->lrange($key,$start,$start+$count); + $c = 0; + foreach($posts as $p) { + if (showPost($p)) $c++; + if ($c == $count) break; + } + return count($posts) == $count+1; +} +</pre><code name="code" class="python">showPost</code> will simply convert and print a Post in HTML while <code name="code" class="python">showUserPosts</code> get range of posts passing them to <code name="code" class="python">showPosts</code>.<h2><a name="Following users">Following users</a></h2>If user id 1000 (antirez) wants to follow user id 1001 (pippo), we can do this with just two SADD:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python python python python python python python python" name="code"> +SADD uid:1000:following 1001 +SADD uid:1001:followers 1000 +</pre>Note the same pattern again and again, in theory with a relational database the list of following and followers is a single table with fields like <code name="code" class="python">following_id</code> and <code name="code" class="python">follower_id</code>. With queries you can extract the followers or following of every user. With a key-value DB that's a bit different as we need to set both the <code name="code" class="python">1000 is following 1001</code> and <code name="code" class="python">1001 is followed by 1000</code> relations. This is the price to pay, but on the other side accessing the data is simpler and ultra-fast. And having this things as separated sets allows us to do interesting stuff, for example using SINTER we can have the intersection of 'following' of two different users, so we may add a feature to our Twitter clone so that it is able to say you at warp speed, when you visit somebody' else profile, "you and foobar have 34 followers in common" and things like that.<br/><br/>You can find the code that sets or removes a following/follower relation at follow.php. It is trivial as you can see. +<h1><a name="Making it horizontally scalable">Making it horizontally scalable</a></h1> +Gentle reader, if you reached this point you are already an hero, thank you. Before to talk about scaling horizontally it is worth to check the performances on a single server. Retwis is <b>amazingly fast</b>, without any kind of cache. On a very slow and loaded server, apache benchmark with 100 parallel clients issuing 100000 requests measured the average pageview to take 5 milliseconds. This means you can serve millions of users every day with just a single Linux box, and this one was monkey asses slow! Go figure with more recent hardware.<br/><br/>So, first of all, probably you will not need more than one server for a lot of applications, even when you have a lot of users. But let's assume we <b>are</b> Twitter and need to handle a huge amount of traffic. What to do? +<h3><a name="Hashing the key">Hashing the key</a></h3> +The first thing to do is to hash the key and issue the request on different servers based on the key hash. There are a lot of well known algorithms to do so, for example check the Redis Ruby library client that implements <i>consistent hashing</i>, but the general idea is that you can turn your key into a number, and than take the reminder of the division of this number by the number of servers you have:<br/><br/><pre class="codeblock python python python python python python python python python python python python python python python python python python python python python python python python" name="code"> +server_id = crc32(key) % number_of_servers +</pre>This has a lot of problems since if you add one server you need to move too much keys and so on, but this is the general idea even if you use a better hashing scheme like consistent hashing.<br/><br/>Ok, are key accesses distributed among the key space? Well, all the user data will be partitioned among different servers. There are no inter-keys operations used (like SINTER, otherwise you need to care that things you want to intersect will end in the same server. <b>This is why Redis unlike memcached does not force a specific hashing scheme, it's application specific</b>). Btw there are keys that are accessed more frequently.<h3><a name="Special keys">Special keys</a></h3>For example every time we post a new message, we <b>need</b> to increment the <code name="code" class="python">global:nextPostId</code> key. How to fix this problem? A Single server will get a lot if increments. The simplest way to handle this is to have a dedicated server just for increments. This is probably an overkill btw unless you have really a lot of traffic. There is another trick. The ID does not really need to be an incremental number, but just <b>it needs to be unique</b>. So you can get a random string long enough to be unlikely (almost impossible, if it's md5-size) to collide, and you are done. We successfully eliminated our main problem to make it really horizontally scalable!<br/><br/>There is another one: global:timeline. There is no fix for this, if you need to take something in order you can split among different servers and <b>then merge</b> when you need to get the data back, or take it ordered and use a single key. Again if you really have so much posts per second, you can use a single server just for this. Remember that with commodity hardware Redis is able to handle 100000 writes for second, that's enough even for Twitter, I guess.<br/><br/>Please feel free to use the comments below for questions and feedbacks. + + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/TypeCommand.html b/doc/TypeCommand.html new file mode 100644 index 000000000..9311d3244 --- /dev/null +++ b/doc/TypeCommand.html @@ -0,0 +1,44 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>TypeCommand: Contents</b><br> <a href="#TYPE _key_">TYPE _key_</a><br> <a href="#Return value">Return value</a><br> <a href="#See also">See also</a> + </div> + + <h1 class="wikiname">TypeCommand</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="TYPE _key_">TYPE _key_</a></h1> +<i>Time complexity: O(1)</i><blockquote>Return the type of the value stored at <i>key</i> in form of astring. The type can be one of "none", "string", "list", "set"."none" is returned if the key does not exist.</blockquote> +<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Single line reply</a>, specifically:<br/><br/><pre class="codeblock python" name="code"> +"none" if the key does not exist +"string" if the key contains a String value +"list" if the key contains a List value +"set" if the key contains a Set value +</pre><h2><a name="See also">See also</a></h2> +<ul><li> <a href="DataTypes.html">Redis Data Types</a></li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/VersionControl.html b/doc/VersionControl.html new file mode 100644 index 000000000..bb249a327 --- /dev/null +++ b/doc/VersionControl.html @@ -0,0 +1,40 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>VersionControl: Contents</b><br> <a href="#VERSION">VERSION</a><br> <a href="#Return value">Return value</a> + </div> + + <h1 class="wikiname">VersionControl</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="VERSION">VERSION</a></h1>Return the server version as a float string. Example:<br/><br/><pre class="codeblock python" name="code"> +VERSION +0.07 +</pre>It is guaranteed that if you compare versions as floats newer versions will be greater than older versions.<h2><a name="Return value">Return value</a></h2><a href="ReplyTypes.html">Single line reply</a> + + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/index.html b/doc/index.html new file mode 100644 index 000000000..0b040564b --- /dev/null +++ b/doc/index.html @@ -0,0 +1,36 @@ + +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> +<html> + <head> + <link type="text/css" rel="stylesheet" href="style.css" /> + </head> + <body> + <div id="page"> + + <div id='header'> + <a href="index.html"> + <img style="border:none" alt="Redis Documentation" src="redis.png"> + </a> + </div> + + <div id="pagecontent"> + <div class="index"> +<!-- This is a (PRE) block. Make sure it's left aligned or your toc title will be off. --> +<b>index: Contents</b><br> <a href="#Redis Documentation">Redis Documentation</a> + </div> + + <h1 class="wikiname">index</h1> + + <div class="summary"> + + </div> + + <div class="narrow"> + <h1><a name="Redis Documentation">Redis Documentation</a></h1>Hello! The followings are pointers to different parts of the Redis Documentation.<br/><br/><ul><li> <a href="README.html">The README</a> is the best starting point to know more about the project.</li><li> <a href="CommandReference.html">The command reference</a> is a description of all the Redis commands with links to command specific pages.</li><li> <a href="ProtocolSpecification.html">The Protocol Specification</a> is all you need in order to implement a Redis client library for a missing language. PHP, Python, Ruby and Erlang are already supported.</li><li> <a href="TwitterAlikeExample.html">This is a tuturial about creating a Twitter clone using *only* Redis as database, no relational DB at all is used</a>, it is a good start to understand the key-value database paradigm.</li><li> <a href="FAQ.html">Our FAQ</a> contains of course some answers to common questions about Redis.</li><li> <a href="Benchmarks.html">The benchmark page</a> is about the speed performances of Redis.</li><li> <b>New!</b> video: <a href="http://mwrc2009.confreaks.com/13-mar-2009-19-24-redis-key-value-nirvana-ezra-zygmuntowicz.html" target="_blank">watch the Ezra Zygmuntowicz talk about Redis</a> to know the most important Redis ideas in few minutes.</li></ul> + </div> + + </div> + </div> + </body> +</html> + diff --git a/doc/redis.png b/doc/redis.png Binary files differnew file mode 100644 index 000000000..4578f00c3 --- /dev/null +++ b/doc/redis.png diff --git a/doc/style.css b/doc/style.css new file mode 100644 index 000000000..bf0f078e1 --- /dev/null +++ b/doc/style.css @@ -0,0 +1,25 @@ +body { + font-family: 'Verdana'; + width:800px; +} + +a { + text-decoration: none; +} + +h1, h2, h3, h4, h5 { + color: #333; +} + +h1 { + font-size: 20px; +} + +.codeblock { + color: darkgreen; + padding:5px; +} + +h1.wikiname { + color: #f55000; +} |
