… any SELECT statement to complete in order to complete locking tables. This means if you have workload which includes some very long SELECT queries you can be potentially waiting for hours for this statement to complete. Here is example how it can look: mysql… tables with read lock | 0 | 0 | 1 | | 10291 | root | localhost | dumptest | Query | 74 | Waiting for global read lock | insert into C values (“a…
Post: How much memory Innodb locks really take ?
July 13, 2006 By 11 Comments
After playing yesterday a bit with INSERT … SELECT I decided to check is Innodb locks are relly as efficient in terms of low… bits per locked row; Now lets see how much exclusinve locks take: mysql> begin; Query OK, 0 rows affected (0.00 sec) mysql> select count… any locks is going to be faster than any of locking modes, however we can see locking overhead is not that large: mysql> select count…
Post: Edge-case behavior of INSERT...ODKU
October 27, 2012 By 6 Comments
…be considered as being defined first. So, MySQL checks our INSERT, sees that the next auto-inc …we try an INSERT … ODKU? First, recall what’s in our table: (root@localhost) [test]> select * from update_test; …be. 1500 queries per second all trying to lock and update the same row is not …
Post: MySQL Slow query log in the table
May 31, 2007 By 1 Comment
…MySQL 5.1 get MySQL slow query log logged in mysql.slow_log table instead of the file as … is used to store query execution time and lock time does not store fractions of the second. …similar structure with needed index and populate it with insert… select statement as you need it. One little gotcha …
Post: Fighting MySQL Replication Lag
September 22, 2008 By 7 Comments
… query design mistakes which result in low hanging fruit troubleshooting MySQL Replication Lag First fact you absolutely need to remember is… be much worse as SELECT may end up being extremely complicated query. It is best to avoid INSERT … SELECT going through replication in 5.0 for many reasons (locking, long query time, waste of…
Post: Percona Server on the Raspberry Pi: Your own MySQL Database Server for Under $80
February 25, 2013 By 10 Comments
… here is how to get Percona Server for MySQL up and running: Insert the SD card into a slot on your laptop… | DEFAULT | Percona-XtraDB, Supports transactions, row-level locking, and foreign keys | YES | YES | YES | [...] mysql> SELECT “Hello World!” AS “Success!” \G *************************** 1. row…
Post: MySQL Error Message Nonsenses
March 16, 2008 By 7 Comments
…about tokens near by but little details: mysql> select * from user oder by pwd; ERROR 1064 (… different transactional storage engines we surely saw lock related tables being far from consistent. …messages produced when this limit is reached: mysql> insert into yt values (66666); ERROR 1114 (HY000): …
Post: Test Drive of Solid
September 22, 2006 By 5 Comments
… locked or even modified unless you require locking read, in which case SELECT FOR UPDATE or SELECT … LOCK…: mysql> begin; Sessino2: mysql> begin; Session1: mysql> insert into test2 values (4,’FEDERATED’); Session2: select * from test2; +—-+——–+ | id | names | +—-+——–+ | 1 | Mysql | |…
Post: Innodb performance gotcha w Larger queries.
August 28, 2009 By 7 Comments
…gap_locks = FALSE; } } The “REPLACE 1000 rows” SQL doesn’t have “SELECT” so, InnoDB scan all of the SQL each times… (* “INSERT” …(trx->isolation_level select_lock_type != LOCK_NONE && trx->mysql_thd != NULL && thd_is_select(trx->mysql_thd)) { /* It is a plain locking SELECT and the isolation level…
Comment: MySQL Server Memory Usage
September 1, 2006 By 21 Comments
…_insert‘, ’17889656′ ‘Com_insert_select‘, ’11′ ‘Com_kill’, ’47′ ‘Com_load’, ’0′ ‘Com_load_master_data’, ’0′ ‘Com_load_master_table’, ’0′ ‘Com_lock…/mysql.sock pid-file=/var/run/mysql/mysql.pid datadir=/db/disk2/mysql/data log-bin=/var/log/mysql/log log-slow-queries=/var/log/mysql…_log_group_home_dir=/var/log/mysql innodb_log_arch_dir=/var/log/mysql innodb_table_locks=0 innodb_buffer_pool_size=1800M…
