diff options
Diffstat (limited to 'Docs/internals.texi')
| -rw-r--r-- | Docs/internals.texi | 209 |
1 files changed, 204 insertions, 5 deletions
diff --git a/Docs/internals.texi b/Docs/internals.texi index 9bbd90a7a3a..e0574df550b 100644 --- a/Docs/internals.texi +++ b/Docs/internals.texi @@ -47,7 +47,7 @@ This is a manual about @strong{MySQL} internals. @menu @end menu -@node caching +@node caching,,, @chapter How MySQL handles caching @strong{MySQL} has the following caches: @@ -89,7 +89,7 @@ found rows are cached in a join cache. One SELECT query can use many join caches in the worst case. @end itemize -@node flush tables +@node flush tables,,, @chapter How MySQL handles flush tables @itemize @bullet @@ -134,7 +134,7 @@ After this it will give other threads a chance to open the same tables. @end itemize -@node Filesort +@node Filesort,,, @chapter How MySQL does sorting (filesort) @itemize @bullet @@ -174,7 +174,7 @@ and then we read the rows in the sorted order into a row buffer @end itemize -@node Coding guidelines +@node Coding guidelines,,, @chapter Coding guidelines @itemize @bullet @@ -289,7 +289,7 @@ Use pointers rather than array indexing when operating on strings. @end itemize -@node mysys functions +@node mysys functions,,, @chapter mysys functions Functions i mysys: (For flags se my_sys.h) @@ -433,6 +433,205 @@ Functions i mysys: (For flags se my_sys.h) void end_key_cache _A((void)); - End key-cacheing. +@node protocol,,, +@chapter MySQL client/server protocol + +Raw packet without compression +============================== +------------------------------------------------- +| Packet Length | Packet no | Data | +| 3 Bytes | 1 Byte | n Bytes | +------------------------------------------------- + +3 Byte packet length + The length is calculated with int3store + See include/global.h for details. + The max packetsize can be 16 MB. +1 Byte packet no + +If no compression is used the first 4 bytes of each paket +is the header of the paket. +The packet number is incremented for each sent packet. The first +packet starts with 0 + +n Byte data + +The packet length can be recalculated with: +length = byte1 + (256 * byte2) + (256 * 256 * byte3) + +Raw packet with compression +=========================== +----------------------------------------------------- +| Packet Length | Packet no | Uncomp. Packet Length | +| 3 Bytes | 1 Byte | 3 Bytes | +----------------------------------------------------- + +3 Byte packet length + The length is calculated with int3store + See include/global.h for details. + The max packetsize can be 16 MB. +1 Byte packet no +3 Byte uncompressed packet length + +If compression is used the first 7 bytes of each paket +is the header of the paket. + +Basic packets +============== +OK-packet + For details see sql/net_pkg.cc + function send_ok + ------------------------------------------------- + | Header | No of Rows | Affected Rows | + | | 1 Byte | 1-8 Byte | + ------------------------------------------------- + | ID (last_insert_id) | Status | Length | + | 1-8 Byte | 2 Byte | 1-8 Byte | + ------------------------------------------------- + | Messagetext | + | n Byte | + ------------------------------------------------- + + Header + 1 byte number of rows ? (always 0 ?) + 1-8 bytes affected rows + 1-8 byte id (last_insert_id) + 2 byte Status (usually 0) + If the OK-packege includes a message: + 1-8 bytes length of message + n bytes messagetext + +Error-packet + ------------------------------------------------- + | Header | Statuscode | Error no | + | | 1 Byte | 2 Byte | + ------------------------------------------------- + | Messagetext | 0x00 | + | n Byte | 1 Byte | + ------------------------------------------------- + + Header + 1 byte status code (0xFF = ERROR) + 2 byte error number (is only sent to new 3.23 clients. + n byte errortext + 1 byte 0x00 + + + +The communication +================= + +> Packet from server to client +< Paket from client tor server + + Login + ------ + > 1. packet + Header + 1 byte protocolversion + n byte serverversion + 1 byte 0x00 + 4 byte threadnumber + 8 byte crypt seed + 1 byte 0x00 + 2 byte CLIENT_xxx options (see include/mysql_com.h + that is supported by the server + 1 byte number of current server charset + 2 byte server status variables (SERVER_STATUS_xxx flags) + 13 byte 0x00 (not used yet). + + < 2. packet + Header + 2 byte CLIENT_xxx options + 3 byte max_allowed_packet for the client + n byte username + 1 byte 0x00 + 8 byte crypted password + 1 byte 0x00 + n byte databasename + 1 byte 0x00 + + > 3. packet + OK-packet + + + Command + -------- + < 1. packet + Header + 1 byte command type (e.g.0x03 = query) + n byte query + + Result set (after command) + -------------------------- + > 2. packet + Header + 1-8 byte field_count (packed with net_store_length()) + + If field_count == 0 (command): + 1-8 byte affected rows + 1-8 byte insert id + 2 bytes server_status (SERVER_STATUS_xx) + + If field_count == NULL_LENGTH (251) + LOAD DATA LOCAL INFILE + + If field_count > 0 Result Set: + + > n packets + Header Info + Column description: 5 data object /column + (See code in unpack_fields()) + + Columninfo for each column: + 1 data block table_name + 1 byte length of block + n byte data + 1 data block field_name + 1 byte length of block... + n byte data + 1 data block display length of field + 1 byte length of block + 3 bytes display length of filed + 1 data block type field of type (enum_field_types) + 1 byte length of block + 1 bytexs field of type + 1 data block flags + 1 byte length of block + 2 byte flags for the columns (NOT_NULL_FLAG, ZEROFILL_FLAG....) + 1 byte decimals + + if table definition: + 1 data block default value + + Actual result (one packet per row): + 4 byte header + 1-8 byte length of data + n data + + +Fieldtype Codes: +================ + + display_length |enum_field_type |flags + ---------------------------------------------------- +Blob 03 FF FF 00 |01 FC |03 90 00 00 +Mediumblob 03 FF FF FF |01 FC |03 90 00 00 +Tinyblob 03 FF 00 00 |01 FC |03 90 00 00 +Text 03 FF FF 00 |01 FC |03 10 00 00 +Mediumtext 03 FF FF FF |01 FC |03 10 00 00 +Tinytext 03 FF 00 00 |01 FC |03 10 00 00 +Integer 03 0B 00 00 |01 03 |03 03 42 00 +Mediumint 03 09 00 00 |01 09 |03 00 00 00 +Smallint 03 06 00 00 |01 02 |03 00 00 00 +Tinyint 03 04 00 00 |01 01 |03 00 00 00 +Varchar 03 XX 00 00 |01 FD |03 00 00 00 +Enum 03 05 00 00 |01 FE |03 00 01 00 +Datetime 03 13 00 00 |01 0C |03 00 00 00 +Timestamp 03 0E 00 00 |01 07 |03 61 04 00 +Time 03 08 00 00 |01 0B |03 00 00 00 +Date 03 0A 00 00 |01 0A |03 00 00 00 + @c The Index was empty, and ugly, so I removed it. (jcole, Sep 7, 2000) |