…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… ie there is no MYISAM like table lock priority problem with pending WRITE query blocks any READ queries to execute on the table. mysql> show …
Post: Using MyISAM in production
June 17, 2006 By 35 Comments
…MyISAM in production. For me it is not only about table locks. Table locks is only one of MyISAM… Concurrency. MyISAM uses table locks and has concurrent inserts which can go concurrently with selects. …queries failing to run, wrong result sets or crashes. Here is my list what I think MyISAM tables…
Post: MyISAM Scalability and Innodb, Falcon Benchmarks
October 12, 2007 By 10 Comments
… scalability problems, this time We are faced with one for MyISAM tables. We saw that several times in synthetic benchmarks but never… simple select query which should be executed without exclusive table locking. Even on 16 threads we’re getting performance worse than with single query. The…
Post: How fast is FLUSH TABLES WITH READ LOCK?
April 24, 2010 By 28 Comments
… the lock, anything else that currently holds the lock must finish what it’s doing. That means that every currently running query, including SELECT queries…TABLES WITH READ LOCK command finally acquires the lock, it must begin flushing data. This does not apply to all storage engines. However, MyISAM…
Post: Slow DROP TABLE
June 16, 2009 By 21 Comments
…Query | 7 | rename result table | ALTER TABLE large_table ENGINE=MyISAM | | 679 | root | localhost | test | Query | 6 | Opening tables | select * from other_table…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…lock_countblogpercona.commanual memlockblogpercona.commanual min_examined_row_limitblogpercona.commanual myisam_block_sizeblogpercona.commanual myisam_data_pointer_sizeblogpercona.commanual myisam…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
…selects to the table until it is executed. It works for storage engines with table locks or if LOCK TABLES are used. So in practice this option is used for MyISAM and MEMORY tables. max_write_lock…
Post: Paul McCullagh answers your questions about PBXT
November 20, 2009 By 2 Comments
…SELECTs under circumstances. The implementation of full-durability has changed the performance characteristics of PBXT from “MyISAM…locks. A normal SELECT does not lock at all. In addition, an UPDATE or DELETE only acquires a temporary row-lock. This lock… the first queries that access PBXT tables may…
Post: INSERT INTO ... SELECT Performance with Innodb tables.
July 12, 2006 By 21 Comments
…. It is important for tables which is being read to be Innodb – even if writes are done in MyISAM table. So why was…, locked 1 2539 lock struct(s), heap size 224576 MySQL thread id 1794751, query id 6994931 localhost root Sending data insert into test select * from sample ——– As you can see INSERT… SELECT has a lot of lock…
Post: Using Multiple Key Caches for MyISAM Scalability
November 26, 2008 By 8 Comments
…MyISAM Does Not Scale, or it does quite well – two main things stopping you is table locks and global mutex on the KeyCache. Table Locks…
