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diff --git a/bdb/docs/ref/txn/intro.html b/bdb/docs/ref/txn/intro.html deleted file mode 100644 index 557481509e0..00000000000 --- a/bdb/docs/ref/txn/intro.html +++ /dev/null @@ -1,86 +0,0 @@ -<!--$Id: intro.so,v 10.14 2000/03/18 21:43:19 bostic Exp $--> -<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--> -<!--All rights reserved.--> -<html> -<head> -<title>Berkeley DB Reference Guide: Berkeley DB and transactions</title> -<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> -<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++"> -</head> -<body bgcolor=white> - <a name="2"><!--meow--></a> -<table><tr valign=top> -<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Transaction Subsystem</dl></h3></td> -<td width="1%"><a href="../../ref/mp/config.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../ref/toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/txn/nested.html"><img src="../../images/next.gif" alt="Next"></a> -</td></tr></table> -<p> -<h1 align=center>Berkeley DB and transactions</h1> -<p>The transaction subsystem makes operations atomic, consistent, isolated, -and durable in the face of system and application failures. The subsystem -requires that the data be properly logged and locked in order to attain -these properties. Berkeley DB contains all the components necessary to -transaction-protect the Berkeley DB access methods and other forms of data may -be protected if they are logged and locked appropriately. -<p>The transaction subsystem is created, initialized, and opened by calls to -<a href="../../api_c/env_open.html">DBENV->open</a> with the <a href="../../api_c/env_open.html#DB_INIT_TXN">DB_INIT_TXN</a> flag specified. Note that -enabling transactions automatically enables logging, but does not enable -locking, as a single thread of control that needed atomicity and -recoverability would not require it. -<p>The <a href="../../api_c/txn_begin.html">txn_begin</a> function starts a transaction, returning an opaque -handle to a transaction. If the parent parameter to <a href="../../api_c/txn_begin.html">txn_begin</a> is -non-NULL, then the new transaction is a child of the designated parent -transaction. -<p>The <a href="../../api_c/txn_abort.html">txn_abort</a> function ends the designated transaction and causes -all updates performed by the transaction to be undone. The end result is -that the database is left in a state identical to the state that existed -prior to the <a href="../../api_c/txn_begin.html">txn_begin</a>. If the aborting transaction has any child -transactions associated with it (even ones that have already been -committed), they are also aborted. Any transactions that are unresolved -(i.e., neither committed nor aborted) when the application or system fails -are aborted during recovery. -<p>The <a href="../../api_c/txn_commit.html">txn_commit</a> function ends the designated transaction and makes -all the updates performed by the transaction permanent, even in the face -of application or system failure. If this is a parent transaction -committing, then all child transactions that individually committed or -had not been resolved are also committed. -<p>Transactions are identified by 32-bit unsigned integers. The ID -associated with any transaction can be obtained using the <a href="../../api_c/txn_id.html">txn_id</a> -function. If an application is maintaining information outside of Berkeley DB -that it wishes to transaction-protect, it should use this transaction ID -as the locking ID. -<p>The <a href="../../api_c/txn_checkpoint.html">txn_checkpoint</a> function causes a transaction checkpoint. A -checkpoint is performed relative to a specific log sequence number (LSN), -referred to as the checkpoint LSN. When a checkpoint completes -successfully, it means that all data buffers whose updates are described -by LSNs less than the checkpoint LSN have been written to disk. This, in -turn, means that the log records less than the checkpoint LSN are no -longer necessary for normal recovery (although they would be required for -catastrophic recovery should the database files be lost) and all log files -containing only records prior to the checkpoint LSN may be safely archived -and removed. -<p>It is possible that in order to complete a transaction checkpoint, it will -be necessary to write a buffer that is currently in use (i.e., is actively -being read or written by some transaction). In this case, -<a href="../../api_c/txn_checkpoint.html">txn_checkpoint</a> will not be able to write the buffer, as doing so -might cause an inconsistent version of the page to be written to disk, -and instead of completing successfully will return with an error code of -<a href="../../api_c/memp_fsync.html#DB_INCOMPLETE">DB_INCOMPLETE</a>. In such cases, the checkpoint can simply be -retried after a short delay. -<p>The interval between successive checkpoints is directly proportional to -the length of time required to run normal recovery. If the interval -between checkpoints is long, then a large number of updates that are -recorded in the log may not yet be written to disk and recovery may take -longer to run. If the interval is short, then data is being written to -disk more frequently, but the recovery time will be shorter. Often, the -checkpoint interval will be tuned for each specific application. -<p>The <a href="../../api_c/txn_stat.html">txn_stat</a> function returns information about the status of -the transaction subsystem. It is the programmatic interface used by the -<a href="../../utility/db_stat.html">db_stat</a> utility. -<p>The transaction system is closed by a call to <a href="../../api_c/env_close.html">DBENV->close</a>. -<p>Finally, the entire transaction system may be removed using the -<a href="../../api_c/env_remove.html">DBENV->remove</a> interface. -<table><tr><td><br></td><td width="1%"><a href="../../ref/mp/config.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../ref/toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/txn/nested.html"><img src="../../images/next.gif" alt="Next"></a> -</td></tr></table> -<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font> -</body> -</html> |