Hello.


>Is there a way to find out which statements take a full table scan to

>optimize them ?



See:

  http://dev.mysql.com/doc/refman/5.0/en/slow-query-log.html







Marco Schierhorn wrote:

> Hey, we´ve a site ( PHP ) where several 1.000 are online at the same time.

> They´re running many sql statements.

> Is there a way to find out which statements take a full table scan to

> optimize them ?

> 

> And i need some help with configuring the my.cnf.

> Below you´ll find our one.

> Which options should i optimize ?

> 

> uname -a :

> 

> Linux m30s06db.ispgateway.de 2.4.29-grsec #10 SMP Mon Jul 4 14:26:46

> CEST 2005 i686 Intel(R) Pentium(R) 4 CPU 3.00GHz GenuineIntel GNU/Linux

> 

> And thats the my.cnf :

> 

> # Example MySQL config file for medium systems.

> #

> # This is for a system with little memory (32M - 64M) where MySQL plays

> # an important part, or systems up to 128M where MySQL is used together

> with

> # other programs (such as a web server)

> #

> # You can copy this file to

> # /etc/my.cnf to set global options,

> # mysql-data-dir/my.cnf to set server-specific options (in this

> # installation this directory is

> /kunden/106120_40670/ms_appl/mysql_4.1.10a/var) or

> # ~/.my.cnf to set user-specific options.

> #

> # In this file, you can use all long options that a program supports.

> # If you want to know which options a program supports, run the program

> # with the "--help" option.

> 

> # The following options will be passed to all MySQL clients

> [client]

> #password = your_password

> port = 3307

> socket = /tmp/mysql.sock

> 

> # Here follows entries for some specific programs

> 

> # The MySQL server

> [mysqld]

> port = 3307

> socket = /tmp/mysql.sock

> skip-locking

> key_buffer = 64M

> max_allowed_packet = 1M

> table_cache = 5M

> sort_buffer_size = 1M

> net_buffer_length = 8K

> read_buffer_size = 1M

> read_rnd_buffer_size = 512K

> myisam_sort_buffer_size = 16M

> record_buffer=1M

> log-slow-queries

> long_query_time = 3

> 

> # Don't listen on a TCP/IP port at all. This can be a security enhancement,

> # if all processes that need to connect to mysqld run on the same host.

> # All interaction with mysqld must be made via Unix sockets or named pipes.

> # Note that using this option without enabling named pipes on Windows

> # (via the "enable-named-pipe" option) will render mysqld useless!

> #

> #

> #skip-networking

> 

> # Replication Master Server (default)

> # binary logging is required for replication

> log-bin

> 

> # required unique id between 1 and 2^32 - 1

> # defaults to 1 if master-host is not set

> # but will not function as a master if omitted

> server-id = 1

> 

> # Replication Slave (comment out master section to use this)

> #

> # To configure this host as a replication slave, you can choose between

> # two methods :

> #

> # 1) Use the CHANGE MASTER TO command (fully described in our manual) -

> # the syntax is:

> #

> # CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,

> # MASTER_USER=<user>, MASTER_PASSWORD=<password> ;

> #

> # where you replace <host>, <user>, <password> by quoted strings and

> # <port> by the master's port number (3306 by default).

> #

> # Example:

> #

> # CHANGE MASTER TO MASTER_HOST='125.564.12.1', MASTER_PORT=3306,

> # MASTER_USER='joe', MASTER_PASSWORD='secret';

> #

> # OR

> #

> # 2) Set the variables below. However, in case you choose this method, then

> # start replication for the first time (even unsuccessfully, for example

> # if you mistyped the password in master-password and the slave fails to

> # connect), the slave will create a master.info file, and any later

> # change in this file to the variables' values below will be ignored and

> # overridden by the content of the master.info file, unless you shutdown

> # the slave server, delete master.info and restart the slaver server.

> # For that reason, you may want to leave the lines below untouched

> # (commented) and instead use CHANGE MASTER TO (see above)

> #

> # required unique id between 2 and 2^32 - 1

> # (and different from the master)

> # defaults to 2 if master-host is set

> # but will not function as a slave if omitted

> #server-id = 2

> #

> # The replication master for this slave - required

> #master-host = <hostname>

> #

> # The username the slave will use for authentication when connecting

> # to the master - required

> #master-user = <username>

> #

> # The password the slave will authenticate with when connecting to

> # the master - required

> #master-password = <password>

> #

> # The port the master is listening on.

> # optional - defaults to 3306

> #master-port = <port>

> #

> # binary logging - not required for slaves, but recommended

> #log-bin

> 

> # Point the following paths to different dedicated disks

> #tmpdir = /tmp/

> #log-update = /path-to-dedicated-directory/hostname

> 

> # Uncomment the following if you are using BDB tables

> #bdb_cache_size = 4M

> #bdb_max_lock = 10000

> 

> # Uncomment the following if you are using InnoDB tables

> #innodb_data_home_dir = /kunden/106120_40670/ms_appl/mysql_4.1.10a/var/

> #innodb_data_file_path = ibdata1:10M:autoextend

> #innodb_log_group_home_dir =

> /kunden/106120_40670/ms_appl/mysql_4.1.10a/var/

> #innodb_log_arch_dir = /kunden/106120_40670/ms_appl/mysql_4.1.10a/var/

> # You can set .._buffer_pool_size up to 50 - 80 %

> # of RAM but beware of setting memory usage too high

> #innodb_buffer_pool_size = 16M

> #innodb_additional_mem_pool_size = 2M

> # Set .._log_file_size to 25 % of buffer pool size

> #innodb_log_file_size = 5M

> #innodb_log_buffer_size = 8M

> #innodb_flush_log_at_trx_commit = 1

> #innodb_lock_wait_timeout = 50

> 

> [mysqldump]

> quick

> max_allowed_packet = 16M

> 

> [mysql]

> no-auto-rehash

> # Remove the next comment character if you are not familiar with SQL

> #safe-updates

> 

> [isamchk]

> key_buffer = 25M

> sort_buffer_size = 25M

> read_buffer = 6M

> write_buffer = 6M

> 

> [myisamchk]

> key_buffer = 25M

> sort_buffer_size = 25M

> read_buffer = 6M

> write_buffer = 6M

> 

> [mysqlhotcopy]

> interactive-timeout

> 



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