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Diffstat (limited to 'Docs')
| -rw-r--r-- | Docs/internals.texi | 1071 | ||||
| -rw-r--r-- | Docs/manual.texi | 140 |
2 files changed, 1188 insertions, 23 deletions
diff --git a/Docs/internals.texi b/Docs/internals.texi index 871e51c50bd..7e364774e39 100644 --- a/Docs/internals.texi +++ b/Docs/internals.texi @@ -1,5 +1,5 @@ \input texinfo @c -*-texinfo-*- -@c Copyright 2002 MySQL AB, TcX AB, Detron HB and Monty Program KB +@c Copyright 2002 MySQL AB @c @c %**start of header @setfilename internals.info @@ -545,6 +545,8 @@ Print query. * basic packets:: * communication:: * fieldtype codes:: +* protocol functions:: +* protocol version 2:: @end menu @node raw packet without compression, raw packet with compression, protocol, protocol @@ -755,7 +757,7 @@ For details, see @file{sql/net_pkg.cc::send_ok()}. n data -@node fieldtype codes, , communication, protocol +@node fieldtype codes, protocol functions, communication, protocol @section Fieldtype Codes @example @@ -779,6 +781,797 @@ Time 03 08 00 00 |01 0B |03 00 00 00 Date 03 0A 00 00 |01 0A |03 00 00 00 @end example +@node protocol functions, protocol version 2, fieldtype codes, protocol +@section Functions used to implement the protocol + +This should be merged with the above one and changed to texi format + +Raw packets +----------- + +- The my_net_xxxx() functions handles the packaging of a stream of data + into a raw packet that contains a packet number, length and data. + +- This is implemented for the server in sql/net_serv.cc. + The client file, libmysql/net.c, is symlinked to this file + +The important functions are: + +my_net_write() Store a packet (= # number of bytes) to be sent +net_flush() Send the packets stored in the buffer +net_write_command() Send a command (1 byte) + packet to the server. +my_net_read() Read a packet + + +Include files +------------- + +- include/mysql.h is included by all MySQL clients. It includes the + MYSQL and MYSQL_RES structures. +- include/mysql_com.h is include by mysql.h and mysql_priv.h (the + server) and includes a lot of common functions and structures to + handle the client/server protocol. + + +Packets from server to client: +----------------------------- + +sql/net_pkg.cc: + + - Sending of error packets + - Sending of OK packets (= end of data) + - Storing of values in a packet + + +sql/sql_base.cc: + + - Function send_fields() sends the field description to the client. + +sql/sql_show.cc: + + - Sends results for a lot of SHOW commands, including: + SHOW DATABASES [like 'wildcard'] + SHOW TABLES [like 'wildcard'] + + +Packets from client to server: +------------------------------ + +This is done in libmysql/libmysql.c + +The important ones are: + +- mysql_real_connect() Connects to a mysqld server +- mysql_real_query() Sends a query to the server and + reads the ok packet or columns header. +- mysql_store_result() Read a result set from the server to memory +- mysql_use_result() Read a result set row by row from the server. + +- net_safe_read() Read a packet from the server with + error handling. +- net_field_length() Reads the length of a packet string. +- simple_command() Sends a command/query to the server. + + + +Connecting to mysqld (the MySQL server) +--------------------------------------- + +- On the client side: libmysql/libmysql.c::mysql_real_connect(). +- On the server side: sql/sql_parse.cc::check_connections() + +The packets sent during a connection are as follows + +Server: Send greeting package (includes server capabilites, server + version and a random string of bytes to be used to scramble + the password. +Client: Sends package with client capabilites, user name, scrambled + password, database name + +Server: Sends ok package or error package. + +Client: If init command specified, send it t the server and read + ok/error package. + + +Password functions +------------------ + +The passwords are scrambled to a random number and are stored in hex +format on the server. + +The password handling is done in sql/password.c. The important +function is 'scramble()', which takes the a password in clear text +and uses this to 'encrypt' the random string sent by the server +to a new message. + +The encrypted message is sent to the server which uses the stored +random number password to encrypt the random string sent to the +client. If this is equal to the new message the client sends to the +server then the password is accepted. + +@node protocol version 2, , protocol functions, protocol +@section Another description of the protocol + +This should be merged with the above one and changed to texi format. + +***************************** +* +* PROTOCOL OVERVIEW +* +***************************** + +The MySQL protocol is relatively simple, and is designed for high performance +through minimisation of overhead, and extensibility through versioning and +options flags. It is a request-response protocol, and does not allow +multitasking or multiplexing over a single connection. There are two packet +formats, 'raw' and 'compressed' (which is used when both client and +server support zlib compression, and the client requests that data be +compressed): + +* RAW PACKET, shorter than 16 M * + ++-----------------------------------------------+ +| Packet Length | Packet no | Data | +| 3 Bytes | 1 Byte | n Bytes | ++-----------------------------------------------+ +^ ^ +| 'HEADER' | ++-------------------------------+ + + + * Packet Length: Calculated with int3store. See include/global.h for + details. The basic computation is length = byte1 + + (256 * byte2) + (256 * 256 * byte3). The max packetsize + can be 16 MB. + + * Packet no: The packet number is incremented for each sent packet. + The first packet for each query from the client + starts with 0. + + * Data: Specific to the operation being performed. Most often + used to send string data, such as a SQL query. + +* COMPRESSED PACKET * + ++---------------------------------------------------+-----------------+ +| Packet Length | Packet no | Uncomp. Packet Length | Compressed Data | +| 3 Bytes | 1 Byte | 3 Bytes | n bytes | ++---------------------------------------------------+-----------------+ +^ ^ +| 'HEADER' | ++---------------------------------------------------+ + + * Packet Length: Calculated with int3store. See include/my_global.h for + details. The basic computation is length = byte1 + + (256 * byte2) + (256 * 256 * byte3). The max packetsize + can be 16 MB. + + * Packet no: The packet number is incremented for each sent packet. + The first packet starts with 0. + + * Uncomp. Packet Length: The length of the original, uncompressed packet + If this is zero then the data is not compressed. + + * Compressed Data: The original packet, compressed with zlib compression + + +When using the compressed protocol, the client/server will only compress +send packets where the new packet is smaller than the not compressed one. +In other words, some packets may be compressed while others will not. + +The 'compressed data' is one or more packets in *RAW PACKET* format. + +***************************** +* +* FLOW OF EVENTS +* +***************************** + +To understand how a client communicates with a MySQL server, it is easiest +to start with a high-level flow of events. Each event section will then be +followed by details of the exact contents of each type of packet involved +in the event flow. + +* * +* CONNECTION ESTABLISHMENT * +* * + +Clients connect to the server via a TCP/IP socket (port 3306 by default), a +Unix Domain Socket, or named pipes (on Windows). Once connected, the +following connection establishment sequence is followed: + ++--------+ +--------+ +| Client | | Server | ++--------+ +--------+ + | | + | Handshake initialisation, including MySQL server version, | + | protocol version and options supported, as well as the seed | + | for the password hash | + | | + | <-------------------------------------------------------------- | + | | + | Client options supported, max packet size for client | + | username, password crypted with seed from server, database | + | name. | + | | + | --------------------------------------------------------------> | + | | + | 'OK' packet if authentication succeeds, 'ERROR' packet if | + | authentication fails. | + | | + | <-------------------------------------------------------------- | + | | + + + +* HANDSHAKE INITIALISATION PACKET * + + ++--------------------------------------------------------------------+ +| Header | Prot. Version | Server Version String | 0x00 | +| | 1 Byte | n bytes | 1 byte | +|--------------------------------------------------------------------| +| Thread Number | Crypt Seed | 0x00 | CLIENT_xxx options | +| | | | supported by server | +| 4 Bytes | 8 Bytes | 1 Byte | 2 Bytes | +|--------------------------------------------------------------------| +| Server charset no. | Server status variables | 0x00 padding | +| 1 Byte | 2 Bytes | 13 bytes | ++--------------------------------------------------------------------+ + + * Protocol version (currently '10') + * Server Version String (e.g. '4.0.5-beta-log'). Can be any length as + it's followed by a 0 byte. + * Thread Number - ID of server thread handling this connection + * Crypt seed - seed used to crypt password in auth packet from client + * CLIENT_xxx options - see include/mysql_com.h + * Server charset no. - Index of charset in use by server + * Server status variables - see include/mysql_com.h + * The padding bytes are reserverd for future extensions to the protocol + +* CLIENT AUTH PACKET * + + ++--------------------------------------------------------------------+ +| Header | CLIENT_xxx options supported | max_allowed_packet | +| | by client | for client | +| | 2 Bytes | 3 bytes | +|--------------------------------------------------------------------| +| User Name | 0x00 | Crypted Password | 0x00 | Database Name | +| n Bytes | 1 Byte | 8 Bytes | 1 Byte | n Bytes | +|--------------------------------------------------------------------| +| 0x00 | +| 1 Byte | ++--------------------------------------------------------------------+ + + * CLIENT_xxx options that this client supports: + +#define CLIENT_LONG_PASSWORD 1 /* new more secure passwords */ +#define CLIENT_FOUND_ROWS 2 /* Found instead of affected rows */ +#define CLIENT_LONG_FLAG 4 /* Get all column flags */ +#define CLIENT_CONNECT_WITH_DB 8 /* One can specify db on connect */ +#define CLIENT_NO_SCHEMA 16 /* Don't allow database.table.column */ +#define CLIENT_COMPRESS 32 /* Can use compression protocol */ +#define CLIENT_ODBC 64 /* Odbc client */ +#define CLIENT_LOCAL_FILES 128 /* Can use LOAD DATA LOCAL */ +#define CLIENT_IGNORE_SPACE 256 /* Ignore spaces before '(' */ +#define CLIENT_INTERACTIVE 1024 /* This is an interactive client */ +#define CLIENT_SSL 2048 /* Switch to SSL after handshake */ +#define CLIENT_IGNORE_SIGPIPE 4096 /* IGNORE sigpipes */ +#define CLIENT_TRANSACTIONS 8192 /* Client knows about transactions */ + + * max_allowed_packet for the client (in 'int3store' form) + * User Name - user to authenticate as. Is followed by a null byte. + * Crypted Password - password crypted with seed given in packet from + server, see scramble() in sql/password.c + * Database name (optional) - initial database to use once connected + Is followed by a null byte + +At the end of every client/server exchange there is either an 'OK' packet +or an 'ERROR' packet sent from the server. To determine whether a packet is +an 'OK' packet, or an 'ERROR' packet, check if the first byte (after the +header) is 0xFF. If it has the value of 0xFF, the packet is an 'ERROR' +packet. + + +* OK PACKET * + +For details, see sql/net_pkg.cc::send_ok() + ++-----------------------------------------------+ +| Header | No of Rows | Affected Rows | +| | 1 Byte | 1-9 Byte | +|-----------------------------------------------| +| ID (last_insert_id) | Status | Length | +| 1-9 Byte | 2 Byte | 1-9 Byte | +|-----------------------------------------------| +| Messagetext | +| n Byte | ++-----------------------------------------------+ + + * Number of rows, always 0 + * Affected rows + * ID (last_insert_id) - value for auto_increment column (if any) + * Status (usually 0) + +In general, in the MySQL protocol, fields in a packet that that +represent numeric data, such as lengths, that are labeled as '1-9' +bytes can be decoded by the following logic: + + If the first byte is '251', the + corresponding column value is NULL (only appropriate in + 'ROW DATA' packets). + + If the first byte is '252', the value stored can be read + from the following 2 bytes as a 16-bit integer. + + + If the first byte is '253' the value stored can be read + from the following 4 bytes as a 32-bit long integer + + + If the first byte is '254', the value stored can be read + from the following 8 bytes as a 64-byte long + + Otherwise (values 0-250), the value stored is the value of the + first byte itself. + + +If the OK-packet includes a message: + + * Length of message + * Message Text + + +* ERROR PACKET * + ++-----------------------------------------------+ +| Header | Status code | Error no | +| | 1 Byte | 2 Byte | +|-----------------------------------------------| +| Messagetext | | +| n Byte | | ++-----------------------------------------------+ + + * Status code (0xFF = ERROR) + * Error number (is only sent to 3.23 and newer clients) + * Error message text (ends at end of packet) + +Note that the error message is not null terminated. +The client code can however assume that the packet ends with a null +as my_net_read() will always add an end-null to all read packets to +make things easier for the client. + +Example: + +Packet dump of client connecting to server: + ++------------------------- Protocol Version (10) +| +| +---------------------- Server Version String (0x00 terminated) +| | +| | +0a 34 2e 30 2e 35 2d 62 . 4 . 0 . 5 - b +65 74 61 2d 6c 6f 67 00 e t a - l o g . +15 00 00 00 2b 5a 65 6c . . . . + Z e l + | | + | +------------ First 4 bytes of crypt seed + | + +------------------------ Thread Number + ++------------------------- Last 4 bytes of crypt seed +| +| +-------- CLIENT_XXX Options supported by server +| | +| +-+--+ +--- Server charset index +| | | | +6f 69 41 46 00 2c 28 08 o i A F . , ( . +02 00 00 00 00 00 00 00 . . . . . . . . +| | +| +---------------------- 0x00 padding begins +| ++------------------------- Server status (0x02 = + SERVER_STATUS_AUTOCOMMIT) + +00 00 00 00 00 00 00 00 . . . . . . . . + +* Client Authentication Response (Username 'test', no database + selected) * + + +--------------------- Packet Length (0x13 = 19 bytes) + | + | +--------------- Packet Sequence # + | | + | | +----------- CLIENT_XXX Options supported by client + | | ++---+---+ | +-+-+ +| | | | | +13 00 00 01 03 00 1e 00 . . . . . . . . +00 74 65 73 74 00 48 5e . t e s t . H ^ + | | | + +----+-----+ +------- Scrambled password, 0x00 terminated + | + +----------------- Username, 0x00 terminated + +57 4a 4e 41 4a 4e 00 00 W J N A J N . . +00 . + + +>From this point on, the server waits for 'commands' from the client +which include queries, database shutdown, quit, change user, etc (see +the COM_xxxx values in include/mysql_com.h for the latest +command codes). + +* * +* COMMAND PROCESSING * +* * + ++--------+ +--------+ +| Client | | Server | ++--------+ +--------+ + | | + | A command packet, with a command code, and string data | + | when appropriate (e.g. a query), (see the COM_xxxx values | + | in include/mysql_com.h for the command codes) | + | | + | --------------------------------------------------------------> | + | | + | A 'RESULT' packet if the command completed successfully, | + | an 'ERROR' packet if the command failed. 'RESULT' packets | + | take different forms (see the details following this chart) | + | depending on whether or not the command returns rows. | + | | + | <-------------------------------------------------------------- | + | | + | n 'FIELD PACKET's (if rows are returned) | + | | + | <-------------------------------------------------------------- | + | | + | 'LAST DATA' packet | + | | + | <-------------------------------------------------------------- | + | | + | n 'ROW PACKET's (if rows are returned) | + | | + | <-------------------------------------------------------------- | + | | + | 'LAST DATA' packet | + | | + | <-------------------------------------------------------------- | + | | + + +* Command Packet * + ++------------------------------------------------------+ +| Header | Command type | Query (if applicable) | +| | 1 Byte | n Bytes | ++------------------------------------------------------+ + + * Command type: (e.g.0x03 = query, see the COM_xxxx values in + include/mysql_com.h) + * Query (if applicable) + +Note that my_net_read() null-terminates all packets on the +receiving side of the channel to make it easier for the code +examining the packets. + +The current command codes are: + + 0x00 COM_SLEEP + 0x01 COM_QUIT + 0x02 COM_INIT_DB + 0x03 COM_QUERY + 0x04 COM_FIELD_LIST + 0x05 COM_CREATE_DB + 0x06 COM_DROP_DB + 0x07 COM_REFRESH + 0x08 COM_SHUTDOWN + 0x09 COM_STATISTICS + 0x0a COM_PROCESS_INFO + 0x0b COM_CONNECT + 0x0c COM_PROCESS_KILL + 0x0d COM_DEBUG + 0x0e COM_PING + 0x0f COM_TIME + 0x10 COM_DELAYED_INSERT + 0x11 COM_CHANGE_USER + 0x12 COM_BINLOG_DUMP + 0x13 COM_TABLE_DUMP + 0x14 COM_CONNECT_OUT + 0x15 COM_REGISTER_SLAVE + +* Result Packet * + +Result packet for a command returning _no_ rows: + ++-----------------------------------------------+ +| Header | Field Count | Affected Rows | +| | 1-9 Bytes | 1-9 Bytes | +|-----------------------------------------------| +| ID (last_insert_id) | Server Status | +| 1-9 Bytes | 2 Bytes | ++-----------------------------------------------+ + + * Field Count: Has value of '0' for commands returning _no_ rows + * Affected rows: Count of rows affected by INSERT/UPDATE/DELETE, etc. + * ID: value of auto_increment column in row (if any). 0 if + * Server Status: Usually 0 + +Result packet for a command returning rows: + ++-------------------------------+ +| Header | Field Count | +| | 1-9 Bytes | ++-------------------------------+ + + * Field Count: number of columns/fields in result set, + (packed with net_store_length() in sql/net_pkg.cc) + +This is followed by as many packets as the number of fields ('Field Count') +that contain the metadata for each column/field (see unpack_fields() in +libmysql/libmysql.c): + + +* FIELD PACKET * + ++-----------------------------------------------+ +| Header | Table Name | +| | length-coded-string | +|-----------------------------------------------| +| Field Name | +| length-code-string | +|-----------------------------------------------| +| Display length of field +| length-coded-binary (4 bytes) | +|-----------------------------------------------| +| Field Type (enum_field_types in mysql_com.h) | +| length-coded-binary (2 bytes) | +|-----------------------------------------------| +| Field Flags | Decimal Places| +| length-coded-binary (3 bytes) | 1 Byte | ++--------------+-------------+------------------+ + + * A length coded string is a string where we first have a packet + length (1-9 bytes, packed_with net_store_length()) followed + by a string. + * A length coded binary is a length (1 byte) followed by an integer + value in low-byte-first order. For the moment this type is always + fixed length in this packet. + + * Table Name - the name of the table the column comes from + * Field Name - the name of the column/field + * Display length of field - length of field + * Field Type - Type of field, see enum_field_types in + include/mysql_com.h + + Current field types are: + + 0x00 FIELD_TYPE_DECIMAL + 0x01 FIELD_TYPE_TINY + 0x02 FIELD_TYPE_SHORT + 0x03 FIELD_TYPE_LONG + 0x04 FIELD_TYPE_FLOAT + 0x05 FIELD_TYPE_DOUBLE + 0x06 FIELD_TYPE_NULL + 0x07 FIELD_TYPE_TIMESTAMP + 0x08 FIELD_TYPE_LONGLONG + 0x09 FIELD_TYPE_INT24 + 0x0a FIELD_TYPE_DATE + 0x0b FIELD_TYPE_TIME + 0x0c FIELD_TYPE_DATETIME + 0x0d FIELD_TYPE_YEAR + 0x0e FIELD_TYPE_NEWDATE + 0xf7 FIELD_TYPE_ENUM + 0xf8 FIELD_TYPE_SET + 0xf9 FIELD_TYPE_TINY_BLOB + 0xfa FIELD_TYPE_MEDIUM_BLOB + 0xfb FIELD_TYPE_LONG_BLOB + 0xfc FIELD_TYPE_BLOB + 0xfd FIELD_TYPE_VAR_STRING + 0xfe FIELD_TYPE_STRING + 0xff FIELD_TYPE_GEOMETRY + + * Field Flags - NOT_NULL_FLAG, PRI_KEY_FLAG, xxx_FLAG in + include/mysql_com.h + + +Note that the packet format in 4.1 has slightly changed to allow more values. + + +* ROW PACKET * + ++-----------------------------------------------+ +| Header | Data Length | Column Data | ....for each column +| | 1-9 Bytes | n Bytes | ++-----------------------------------------------+ + + * Data Length: (packed with net_store_length() in sql/net_pkg.cc) + + If 'Data Length' == 0, this is an 'ERROR PACKET'. + + * Column Data: String representation of data. MySQL always sends result set + data as strings. + +* LAST DATA PACKET * + +Packet length is < 9 bytes, and first byte is 0xFE + ++--------+ +| 0xFE | +| 1 Byte | ++--------+ + +Examples: + +*********** +* +* INITDB Command +* +*********** + +A client issuing an 'INITDB' (select the database to use) command, +followed by an 'OK' packet with no rows and no affected rows from +the server: + +* INITDB (select database to use) 'COMMAND' Packet * + + +--------------------- Packet Length (5 bytes) + | + | +--------------- Packet Sequence # + | | + | | +------------ Command # (INITDB = 0x02) + | | ++---+---+ | | +---------- Beginning of query data +| | | | | +05 00 00 00 02 74 65 73 . . . . . t e s +74 t + +* 'OK' Packet with no rows, and no rows affected * + + +--------------------- Packet Length (3 bytes) + | + | +--------------- Packet Sequence # + | | ++---+---+ | +| | | +03 00 00 01 00 00 00 . . . . . . . + + +*********** +* +* SELECT query example +* +*********** + +Client issuing a 'SELECT *' query on the following table: + + CREATE TABLE number_test (minBigInt bigint, + maxBigInt bigint, + testBigInt bigint) + +* 'COMMAND' Packet with QUERY (select ...) * + + +--------------------- Packet Length (26) + | + | +--------------- Packet Sequence # + | | + | | +------------ Command # (QUERY = 0x03) + | | ++---+---+ | | +---------- Beginning of query data +| | | | | +1a 00 00 00 03 53 45 4c . . . . . S E L +45 43 54 20 2a 20 66 72 E C T . * . f r +6f 6d 20 6e 75 6d 62 65 o m . n u m b e +72 5f 74 65 73 74 r _ t e s t + + +and receiving an 'OK' packet with a 'FIELD COUNT' of 3 + + +* 'OK' Packet with 3 fields * + + +--------------------- Packet Length (3 bytes) + | + | +--------------- Packet Sequence # + | | ++---+---+ | +| | | +01 00 00 01 03 . . . . . + +Followed immediately by 3 'FIELD' Packets. Note, the individual packets +are delimitted by =======, so that all fields can be annotated in the first +'FIELD' packet example: + +============================================================= + + +--------------------- Packet Length (0x1f = 31 bytes) + | + | +--------------- Packet Sequence # + | | + | | +------------ Block Length (0x0b = 11 bytes) + | | | ++---+---+ | | +--------- Table Name (11 bytes long) +| | | | | +1f 00 00 02 0b 6e 75 6d . . . . . n u m +62 65 72 5f 74 65 73 74 b e r _ t e s t + + +------------------------ Block Length (9 bytes) + | + | +--------------------- Column Name (9 bytes long) + | | +09 6d 69 6e 42 69 67 49 . m i n B i g I +6e 74 03 14 00 00 01 08 n t . . . . . . + | | | | | + | +---+---+ | +--- Field Type (0x08 = FIELD_TYPE_LONGLONG) + | | | + | | +------ Block Length (1) + | | + | +--------------- Display Length (0x14 = 20 chars) + | + +------------------ Block Length (3) + + +------------------------ Block Length (2) + | + | +-------------------- Field Flags (0 - no flags set) + | | + | +---+ +--------------- Decimal Places (0) + | | | | +02 00 00 00 . . . . + +============================================================= + +'FIELD' packet for the 'number_Test.maxBigInt' column + +1f 00 00 03 0b 6e 75 6d . . . . . n u m +62 65 72 5f 74 65 73 74 b e r _ t e s t +09 6d 61 78 42 69 67 49 . m a x B i g I +6e 74 03 14 00 00 01 08 n t . . . . . . +02 00 00 00 . . . . + +============================================================= + +'FIELD' packet for the 'number_test.testBigInt' column + +20 00 00 04 0b 6e 75 6d . . . . . n u m +62 65 72 5f 74 65 73 74 b e r _ t e s t +0a 74 65 73 74 42 69 67 . t e st B i g +49 6e 74 03 14 00 00 01 I n t . . . . . +08 02 00 00 00 . . . . . +============================================================= + +Followed immediately by one 'LAST DATA' packet: + +fe 00 . . + +Followed immediately by 'n' row packets (in this case, only +one packet is sent from the server, for simplicity's sake): + + + +--------------------- Packet Length (0x52 = 82 bytes) + | + | +--------------- Packet Sequence # + | | + | | +------------ Data Length (0x14 = 20 bytes) + | | | ++---+---+ | | +--------- String Data '-9223372036854775808' +| | | | | (repeat Data Length/Data sequence) + +52 00 00 06 14 2d 39 32 . . . . . - 9 2 +32 33 33 37 32 30 33 36 2 3 3 7 2 0 3 6 +38 35 34 37 37 35 38 30 8 5 4 7 7 5 8 0 +38 13 39 32 32 33 33 37 8 . 9 2 2 3 3 7 +32 30 33 36 38 35 34 37 2 0 3 6 8 5 4 7 +37 35 38 30 37 0a 36 31 7 5 8 0 7 . 6 1 +34 37 34 38 33 36 34 37 4 7 4 8 3 6 4 7 + +Followed immediately by one 'LAST DATA' packet: + +fe 00 . . + + + @c The Index was empty, and ugly, so I removed it. (jcole, Sep 7, 2000) @c @node Index @@ -786,6 +1579,276 @@ Date 03 0A 00 00 |01 0A |03 00 00 00 @c @printindex fn +@node 4.1 protocol,,, +@subchapter MySQL 4.1 protocol + +@node 4.1 protocol changes,,, +@section Changes to 4.0 protocol in 4.1 + +All basic package handling is identical to 4.0. When communication +with an old 4.0 or 3.x client we will use the old protocol. + +The new things that we support with 4.1 are: + +@itemize @bullet +@item +Warnings +@item +Prepared statements +@item +Binary protocol (will be much faster than the current protocol that +converts everything to strings) +@end itemize + + +What has changed in 4.1 are: + +@itemize @bullet +@item +A lot of new field information (database, real table name etc) +@item +The 'ok' packet has more status fields +@item +The 'end' packet (send last for each result set) now contains some +extra information +@item +New protocol for prepared statements. In this case all parameters and +results will sent as binary (low-byte-first). +@end itemize + + +@node 4.1 field package,,, +@section 4.1 field description package + +The field description package is sent as a response to a query that +contains a result set. It can be distinguished from a ok package by +the fact that the first byte can't be 0 for a field package. +@xref {4.1 ok package}. + +The header package has the following structure: + +@multitable @columnfractions .10 .90 +@item Size @tab Comment +@item 1-9 @tab Number of columns in result set (never 0) +@item 1-9 @tab Extra information sent be some command (SHOW COLUMNS +uses this to send the number of rows in the table) +@end multitable + +This package is always followed by a field description set. +@xref{4.1 field desc}. + +@node 4.1 field desc,,, +@section 4.1 field description result set + +The field description result set contains the meta info for a result set. + +@multitable @columnfractions .20 .80 +@item Type @tab Comment +@item string @tab Database name +@item string @tab Table name alias (or table name if no alias) +@item string @tab Real table name +@item string @tab Alias for column name (or column name if not used) +@item 3 byte int @tab Length of column definition +@item 1 byte int @tab Enum value for field type +@item 3 byte int @tab 2 byte column flags (NOT_NULL_FLAG etc..) + 1 byte number of decimals. +@item string int @tab Default value, only set when using mysql_list_fields(). +@end multitable + + +@node 4.1 ok package,,, +@section 4.1 ok package + +The ok package is the first that is sent as an response for a query +that didn't return a result set. + +The ok package has the following structure: + +@multitable @columnfractions .10 .90 +@item Size @tab Comment +@item 1 @tab 0 ; Marker for ok package +@item 1-9 @tab Affected rows +@item 1-9 @tab Last insert id (0 if one wasn't used) +@item 2 @tab Server status; Can be used by client to check if we are inside an transaction +@item 2 @tab Warning count +@item 1-9 @tab Message length (optional) +@item xxx @tab Message (optional) +@end multitable + +Size 1-9 means that the parameter is packed in to 1-9 bytes depending on +the value. (See function sql/net_pkg.cc::net_store_length). + +The message is optional. For example for multi line INSERT it +contains a string for how many rows was inserted / deleted. + + +@node 4.1 end package,,, +@section 4.1 end package + +The end package is sent as the last package for + +@itemize @bullet +@item +End of field information +@item +End of parameter type information +@item +End of result set +@end itemize + +The end package has the following structure: + +@multitable @columnfractions .10 .90 +@item Size @tab Comment +@item 1 @tab 254 ; Marker for EOF package +@item 2 @tab Warning count +@item 2 @tab Status flags (For flags like SERVER_STATUS_MORE_RESULTS) +@end multitable + +Note that a normal package may start with byte 254, which means +'length stored in 9 bytes'. One can different between these cases +by checking the packet length < 9 bytes (in which case it's and end +packet). + + +@node 4.1 error package +@section 4.1 error package. + +The error package is sent when something goes wrong. +The error package has the following structure: + +@multitable @columnfractions .10 .90 +@item Size @tab Comment +@item 1 @tab 255 Error package marker +@item 1-255 @tab Null terminated error message +@end multitable + +The client/server protocol is designed in such a way that a package +can only start with 255 if it's an error package. + + +@node 4.1 prep init,,, +@section 4.1 prepared statement init package + +This is the return package when one sends a query with the COM_PREPARE +command. + +@multitable @columnfractions .10 .90 +@item Size @tab Comment +@item 4 @tab Statement handler id +@item 2 @tab Number of columns in result set +@item 2 @tab Number of parameters in query +@end multitable + +After this, there is a packet that contains the following for each +parameter in the query: + +@multitable @columnfractions .10 .90 +@item Size @tab Comment +@item 2 @tab Enum value for field type. (MYSQL_TYPE_UNKNOWN if not known) +@item 2 @tab 2 byte column flags (NOT_NULL_FLAG etc) +@item 1 @tab Number of decimals +@item 4 @tab Max column length. +@end itemize + +Note that the above is not yet in 4.1 but will be added this month. + +As MySQL can have a parameter 'anywhere' it will in many cases not be +able to provide the optimal information for all parameters. + +If number of columns, in the header package, is not 0 then the +prepared statement will contain a result set. In this case the package +is followed by a field description result set. @xref{4.1 field descr}. + + +@node 4.1 long data,,, +@section 4.1 long data handling + +This is used by mysql_send_long_data() to set any parameter to a string +value. One can call mysql_send_long_data() multiple times for the +same parameter; The server will concatenate the results to a one big +string. + +The server will not require an end package for the string. +mysql_send_long_data() is responsible updating a flag that all data +has been sent. (Ie; That the last call to mysql_send_long_data() has +the 'last_data' flag set). + +This package is sent from client -> server: + +@multitable @columnfractions .10 .90 +@item Size @tab Comment +@item 4 @tab Statement handler +@item 2 @tab Parameter number +@item 2 @tab Type of parameter (not used at this point) +@item # @tab data (Rest of package) +@end itemize + +The server will NOT send an @code{ok} or @code{error} package in +responce for this. If there is any errors (like to big string), one +will get the error when calling execute. + +@node 4.1 execute,,, +@section 4.1 execute + +On execute we send all parameters to the server in a COM_EXECUTE +package. + +The package contains the following information: + +@multitable @columnfractions .30 .70 +@item Size @tab Comment +@item (param_count+7)/8 @tab Null bit map +@item 1 @tab new_parameter_bound flag. Is set to 1 for first +execute or if one has rebound the parameters. +@item 2*param_count @tab Type of parameters (only given if new_parameter_bound flag is 1) +@item # @tab Parameter data, repeated for each parameter that are +NOT NULL and not used with mysql_send_long_data(). +@end itemize + +The null-bit-map is for all parameters (including parameters sent with +'mysql_send_long_data). If parameter 0 is NULL, then bit 0 in the +null-bit-map should be 1 (ie: first byte should be 1) + +The parameters are stored the following ways: + +@multitable @columnfractions .20 .10 .70 +@item Type @tab Size @tab Comment +@item tynyint @tab 1 @tab One byte integer +@item short @tab 2 @tab +@item int @tab 4 @tab +@item longlong @tab 8 @tab +@item float @tab 4 @tab +@item double @tab 8 @tab +@item string @tab 1-9 + # @tab Packed string length + string +@end multitable + +The result for this will be either an ok package or a binary result +set. + +@node 4.1 binary result,,, +@section 4.1 binary result set + +A binary result are sent the following way. + +For each result row: + +@itemize +@item +null bit map with first two bits set to 01 (bit 0,1 value 1) +@item +parameter data, repeated for each not null parameter. +@end itemize + +The idea with the reserving two bits in the null map is that we can +use standard error (first byte 255) and ok packages (first byte 0) +to end a result sets. + +Except that the null-bit-map is shifted two steps, the server is +sending the data to the client the same way that the server is sending +bound parameters to the client. The server is always sending the data +as type given for 'column type' for respective column. It's up to the +client to convert the parameter to the requested type. + @node Fulltext Search, , protocol, Top @chapter Fulltext Search in MySQL @@ -794,10 +1857,10 @@ fulltext search algorithms. Now it's just unsorted notes. @menu -* Weighting in boolean mode:: +* Weighting in boolean mode:: @end menu -@node Weighting in boolean mode, , , Fulltext Search +@node Weighting in boolean mode, , Fulltext Search, Fulltext Search @section Weighting in boolean mode The basic idea is as follows: in expression diff --git a/Docs/manual.texi b/Docs/manual.texi index c39da1e37d1..283ad00d80f 100644 --- a/Docs/manual.texi +++ b/Docs/manual.texi @@ -8202,6 +8202,10 @@ The following startup variables/options have been renamed: The startup options @code{record_buffer}, @code{sort_buffer} and @code{warnings} will still work in MySQL 4.0 but are deprecated. @item +The mysqld option @code{--safe_show_database} doesn't work anymore. One +should instead give the @code{SHOW DATABASES} privileges to everyone that +need to see all databases. +@item The following SQL variables have changed name. @c arjen note: New table, not yet measured for O'Reilly/DocBook. @multitable @columnfractions .50 .50 @@ -19879,7 +19883,6 @@ differ somewhat: | query_cache_limit | 1048576 | | query_cache_size | 0 | | query_cache_type | ON | -| safe_show_database | OFF | | server_id | 0 | | slave_net_timeout | 3600 | | skip_external_locking | ON | @@ -20314,7 +20317,8 @@ This may be set (only numeric) to Don't show databases for which the user doesn't have any database or table privileges. This can improve security if you're concerned about people being able to see what databases other users have. See also -@code{skip_show_database}. +@code{skip_show_database}. This option is deprecated as one should instead +use the @code{SHOW DATABASES} privilege instead. @item @code{server_id} The value of the @code{--server-id} option. @@ -20327,7 +20331,7 @@ Is ON if we only allow local (socket) connections. @item @code{skip_show_database} This prevents people from doing @code{SHOW DATABASES} if they don't have -the @code{PROCESS} privilege. This can improve security if you're +the @code{SHOW DATABASE} privilege. This can improve security if you're concerned about people being able to see what databases other users have. See also @code{safe_show_database}. @@ -23506,17 +23510,21 @@ will be logged in the execution order. Updates to non-transactional tables are stored in the binary log immediately after execution. For transactional tables such as @code{BDB} or @code{InnoDB} tables, all updates (@code{UPDATE}, @code{DELETE} -or @code{INSERT}) that change tables are cached until a @code{COMMIT}. +or @code{INSERT}) that change tables are cached until a @code{COMMIT} command +is sent to the server. At this point mysqld writes the whole transaction to +the binary log before the @code{COMMIT} is executed. Every thread will, on start, allocate a buffer of @code{binlog_cache_size} to buffer queries. If a query is bigger than this, the thread will open -a temporary file to handle the bigger cache. The temporary file will +a temporary file to store the transcation. The temporary file will be deleted when the thread ends. -The @code{max_binlog_cache_size} can be used to restrict the total size used -to cache a multi-query transaction. +The @code{max_binlog_cache_size} (default 4G) can be used to restrict +the total size used to cache a multi-query transaction. If a transaction is +bigger than this it will fail and roll back. If you are using the update or binary log, concurrent inserts will -not work together with @code{CREATE ... SELECT} and @code{INSERT ... SELECT}. +be converted to normal inserts when using @code{CREATE ... SELECT} and +@code{INSERT ... SELECT}. This is to ensure that you can recreate an exact copy of your tables by applying the log on a backup. @@ -23683,7 +23691,7 @@ started}, your slaves may fail. Please see the following table for an indication of master-slave compatibility between different versions. With regard to version 4.0, -we recommend using same version on both sides. +we recommend using at least 4.0.4 on both sides. @c FIX arjen 2002-07-17 new table, not yet measured for XML/DocBook. @multitable @columnfractions .10 .15 .15 .10 .10 .10 @@ -24350,7 +24358,7 @@ may be used with @code{IO_THREAD} and @code{SQL_THREAD} options. (Slave) @tab Re-enables update logging if the user has the @code{SUPER} privilege. Ignored otherwise. (Master) -@item @code{GLOBAL SET SQL_SLAVE_SKIP_COUNTER=n} +@item @code{SET GLOBAL SQL_SLAVE_SKIP_COUNTER=n} @tab Skip the next @code{n} events from the master. Only valid when the slave thread is not running, otherwise, gives an error. Useful for recovering from replication glitches. @@ -25510,7 +25518,7 @@ temporary table to hold the result. This typically happens if you do an @code{ORDER BY} on a different column set than you did a @code{GROUP BY} on. -@item Where used +@item Using where (was @code{where used}) A @code{WHERE} clause will be used to restrict which rows will be matched against the next table or sent to the client. If you don't have this information and the table is of type @code{ALL} or @code{index}, @@ -25670,7 +25678,7 @@ Executing the @code{EXPLAIN} statement again produces this result: @example table type possible_keys key key_len ref rows Extra -tt ALL AssignedPC,ClientID,ActualPC NULL NULL NULL 3872 where used +tt ALL AssignedPC,ClientID,ActualPC NULL NULL NULL 3872 Using where do ALL PRIMARY NULL NULL NULL 2135 range checked for each record (key map: 1) et_1 ALL PRIMARY NULL NULL NULL 74 @@ -25696,7 +25704,7 @@ Now @code{EXPLAIN} produces the output shown here: @example table type possible_keys key key_len ref rows Extra et ALL PRIMARY NULL NULL NULL 74 -tt ref AssignedPC, ActualPC 15 et.EMPLOYID 52 where used +tt ref AssignedPC, ActualPC 15 et.EMPLOYID 52 Using where ClientID, ActualPC et_1 eq_ref PRIMARY PRIMARY 15 tt.AssignedPC 1 @@ -25719,7 +25727,7 @@ Now the join is perfect, and @code{EXPLAIN} produces this result: @example table type possible_keys key key_len ref rows Extra -tt ALL AssignedPC NULL NULL NULL 3872 where used +tt ALL AssignedPC NULL NULL NULL 3872 Using where ClientID, ActualPC et eq_ref PRIMARY PRIMARY 15 tt.ActualPC 1 @@ -28868,7 +28876,6 @@ and if you can use @code{GLOBAL} or @code{SESSION} with them. @item read_buffer_size @tab num @tab GLOBAL | SESSION @item read_rnd_buffer_size @tab num @tab GLOBAL | SESSION @item rpl_recovery_rank @tab num @tab GLOBAL -@item safe_show_database @tab bool @tab GLOBAL @item server_id @tab num @tab GLOBAL @item slave_compressed_protocol @tab bool @tab GLOBAL @item slave_net_timeout @tab num @tab GLOBAL @@ -38698,8 +38705,8 @@ SUM_OVER_ALL_KEYS(max_length_of_key + sizeof(char*) * 2) * Table and index:: Table and Index Structures * File space management:: File Space Management and Disk I/O * Error handling:: Error Handling -* InnoDB change history:: InnoDB Change History * InnoDB restrictions:: Restrictions on InnoDB Tables +* InnoDB change history:: InnoDB Change History * InnoDB contact information:: InnoDB Contact Information. @end menu @@ -50735,6 +50742,7 @@ this means that the version has not yet been released! @c Please don't add a new version here without also updating ../configure.in! @menu +* News-4.1.x:: * News-4.0.x:: Changes in release 4.0.x (Beta) * News-3.23.x:: Changes in release 3.23.x (Stable) * News-3.22.x:: Changes in release 3.22.x (Older; Still supported) @@ -50744,7 +50752,77 @@ this means that the version has not yet been released! @end menu -@node News-4.0.x, News-3.23.x, News, News +@node News-4.1.x, News-4.0.x, News, News +@appendixsec Changes in release 4.1.x (Alpha) + +@cindex changes, version 4.1 + +Version 4.1 of the MySQL server includes many enhancements and new features: + +@itemize @bullet +@item +Sub selects: @code{SELECT * from t1 where t1.a=(SELECT t2.b FROM t2)}. +@item +Character sets to be defined per column, table and database. +@item +Unicode (UTF8) support. +@item +Derived tables: @code{SELECT a from t1, (select * from t2) WHERE t1.a=t2.a} +@item +@code{BTREE} index on @code{HEAP} tables. +@item +Support for GIS (Geometrical data). +@item +@code{SHOW WARNINGS}; Shows warnings for the last command. +@end itemize + +For a full list of changes, please refer to the changelog sections for +each individual 4.1.x release. + +@menu +* News-4.1.0:: +@end menu + +@node News-4.1.0, , News-4.1.x, News-4.1.x +@appendixsubsec Changes in release 4.1.0 +@itemize +@item +One can specify many temporary directories to be used in a round-robin +fasion with: @code{--tmpdir=dirname1:dirname2:dirname3}. +@item +Sub selects: @code{SELECT * from t1 where t1.a=(SELECT t2.b FROM t2)}. +@item +Character sets to be defined per column, table and database. +@item +Unicode (UTF8) support. +@item +Derived tables: @code{SELECT a from t1, (select * from t2) WHERE t1.a=t2.a} +@item +@code{BTREE} index on @code{HEAP} tables. +@item +Faster embedded server. +@item +One can add a comment per column in @code{CREATE TABLE}. +@item +@code{SHOW FULL COLUMNS FROM table_name} shows column comments. +@item +@code{ALTER DATABASE}. +@item +Support for GIS (Geometrical data). +@item +@code{SHOW WARNINGS}; Shows warnings from the last command. +@item +One can specify a column type for a colum in @code{CREATE TABLE +... SELECT} by defining the column in the @code{CREATE} part + +@example +CREATE TABLE foo (a tinyint not null) SELECT b+1 AS 'a' FROM bar; +@end example + +@end itemize + + +@node News-4.0.x, News-3.23.x, News-4.1.x, News @appendixsec Changes in release 4.0.x (Beta) @cindex changes, version 4.0 @@ -50815,6 +50893,19 @@ each individual 4.0.x release. @appendixsubsec Changes in release 4.0.5 @itemize @item +When one uses the @code{--open-files-limit=#} option to @code{mysqld_safe} +it's now passed on to @code{mysqld} +@item +Fixed that @code{GROUP BY} on columns that may have a @code{NULL} value +doesn't always use disk based temporary tables. +@item +Changed output from @code{EXPLAIN} from @code{'where used'} to +@code{'Using where'} to make it more in line with other output. +@item +Removed variable @code{safe_show_database} as it was not used anymore. +@item +Read @code{--des-key-file} relative to database directory. +@item Small code improvement in multi-table updates @item Fixed a newly introduced bug that caused @code{ORDER BY ... LIMIT #} @@ -51680,6 +51771,11 @@ not yet 100% confident in this code. @appendixsubsec Changes in release 3.23.54 @itemize @item +Allow one to start multiple MySQL servers on windows (code backported +from 4.0.2). +@item +Fixed that @code{--core-file} works on Linux (at least on kernel 2.4.18). +@item Fixed a problem with BDB and @code{ALTER TABLE}. @item Fixed reference to freed memory when doing complicated @code{GROUP BY @@ -51765,6 +51861,11 @@ Changed initialisation of @code{RND()} to make it less predicatable. Fixed problem with @code{GROUP BY} on result with expression that created a @code{BLOB} field. @item +Fixed problem with @code{GROUP BY} on columns that have NULL values. To +solve this we now create an MyISAM temporary table when doing a group by +on a possible NULL item. In MySQL 4.0.5 we can again use in memory HEAP +tables for this case. +@item Fixed problem with privilege tables when downgrading from 4.0.2 to 3.23. @item Fixed thread bug in @code{SLAVE START}, @code{SLAVE STOP} and automatic repair @@ -52506,8 +52607,9 @@ long as @code{server-id} is set and valid @file{master.info} is present. Partial updates (terminated with kill) are now logged with a special error code to the binary log. Slave will refuse to execute them if the error code indicates the update was terminated abnormally, and will have to be recovered -with @code{SET SQL_SLAVE_SKIP_COUNTER=1; SLAVE START} after a manual sanity -check/correction of data integrity. +with @code{SET SQL_SLAVE_SKIP_COUNTER=1; SLAVE START} after a manual +sanity check/correction of data integrity. Update: In 4.0.3 and above +you have to use @code{SET GLOBAL}. @item Fixed bug that erroneously logged a drop of internal temporary table on thread termination to the binary log -- this bug affected replication. |