merged

@menu

@end menu

@node caching

@node caching,,,

@chapter How MySQL handles caching

@strong{MySQL} has the following caches:

join caches in the worst case.

@end itemize

@node flush tables

@node flush tables,,,

@chapter How MySQL handles flush tables

@itemize @bullet

@end itemize

@node Filesort

@node Filesort,,,

@chapter How MySQL does sorting (filesort)

@itemize @bullet

@end itemize

@node Coding guidelines

@node Coding guidelines,,,

@chapter Coding guidelines

@itemize @bullet

@end itemize

@node mysys functions

@node mysys functions,,,

@chapter mysys functions

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)

How MySQL Compares to PostgreSQL

* MySQL-PostgreSQL goals::      

* MySQL-PostgreSQL features::   

* MySQL-PostgreSQL benchmarks::  

MySQL and PostgreSQL development goals

* MySQL-PostgreSQL features::   

* MySQL-PostgreSQL benchmarks::  

* MySQL-PostgreSQL goals::      MySQL and PostgreSQL development strategies

* MySQL-PostgreSQL features::   Featurevise Comparison of MySQL and PostgreSQL

* MySQL-PostgreSQL benchmarks::  Benchmarking MySQL and PostgreSQL

MySQL Internals

administration of @strong{MySQL} databases, creation of new databases and 

tables, editing, and more.

@item @uref{http://dlabs.4t2.com}

Dexter, a small server written in Perl which can be used as a proxy server for

@strong{MySQL} or as a database extender.

@item @uref{http://www.scibit.com/Products/Software/Utils/Mascon.asp}

Mascon is a powerful Win32 GUI for administering MySQL databases.

named pipe connections.  You should use either @code{mysqld-nt} or

@code{mysqld-max-nt}.)

If @code{mysqld} doesn't start, please check whether or not the

@file{\mysql\data\mysql.err} file contains any reason for this.  You can also

try to start the server with @code{mysqld --standalone};  In this case, you may

get some useful information on the screen that may help solve the problem.

If @code{mysqld} doesn't start, please check the

@file{\mysql\data\mysql.err} file to see if the server wrote any message

there to indicate the cause of the problem.  You can also try to start

the server with @code{mysqld --standalone};  In this case, you may get

some useful information on the screen that may help solve the problem.

The last option is to start @code{mysqld} with @code{--standalone

--debug}.  In this case @code{mysqld} will write a log file

C:\> C:\mysql\bin\mysqld-max-nt --install

@end example

(You can also use @code{mysqld} binaries that don't end with

@code{-nt.exe} on NT, but those cannot be started as a service or use

named pipes.)

(Under Windows NT, you can actually install any of the server binaries

as a service, but only those having names that end with @code{-nt.exe}

provide support for named pipes.)

You can start and stop the @strong{MySQL} service with these commands:

#ifndef univ_i

#define univ_i

#undef UNIV_INTEL_X86

#if (defined(_WIN32) || defined(_WIN64)) && !defined(MYSQL_SERVER)

#define __WIN__

#include <windows.h>

    --mysqld=*)

       TMP=`$ECHO "$1" | $SED -e "s;--mysqld-=;"`

       EXTRA_MYSQL_TEST_OPT="$EXTRA_MYSQL_TEST_OPT $TMP"

       EXTRA_SLAVE_MYSQLD_OPT="$EXTRA_SLAVE_MYSQLD_OPT $TMP"

       ;;

    --gcov )

      if [ x$BINARY_DIST = x1 ] ; then

	$ECHO ""

        $ECHO "The log files in $MYSQL_TEST_DIR/var/log may give you some hint"

	$ECHO "of what when wrong."

	$ECHO ""

	$ECHO "Please follow the instructions outlined at"

	$ECHO "http://www.mysql.com/doc/R/e/Reporting_mysqltest_bugs.html"

	$ECHO "to find the reason to this problem and how to report this."

	$ECHO "If you want to report this error, please read first the documentation at"

        $ECHO "http://www.mysql.com/doc/M/y/MySQL_test_suite.html"

    fi

}

	    --pid-file=$MASTER_MYPID \

	    --socket=$MASTER_MYSOCK \

            --log=$MASTER_MYLOG --default-character-set=latin1 \

	    --core \

	    --tmpdir=$MYSQL_TMP_DIR \

	    --language=english \

            --innodb_data_file_path=ibdata1:50M \

# Bug when using comparions of strings and integers.

#

drop table if exists t1;

CREATE TABLE t1 (id CHAR(12) not null, PRIMARY KEY (id));

insert into t1 values ('000000000001'),('000000000002');

explain select * from t1 where id=000000000001;