…MySQL replication from this instance, since MySQL replication is asynchronous. What about semi-sync MySQL…send all your writes to one node. This should prevent the deadlock errors, but will not change the lock…Conclusion Choosing a system to replicate your data to a distributed system requires …
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… at the Meta Data Locking behavior prior to MySQL 5.5.3 Metadata Locking behavior prior to MySQL 5.5.3 Prior to MySQL 5.5… | | preparing | 0.000006 | | executing | 0.000001 | | Sorting result | 0.000002 | | Sending data | 0.000040 | | end | 0.000003 | | query end | 0.000002 | | closing…
Post: Innodb Table Locks
July 31, 2012 By 4 Comments
… 26 sec mysql tables in use 2, locked 0 MySQL thread id 53038, OS thread handle 0x7ff759b22700, query id 3918786 localhost root Sending data select… lock struct(s), heap size 1948088, 10008317 row lock(s) MySQL thread id 53173, OS thread handle 0x7ff75963b700, query id 3936362 localhost root Sending data…
Post: How FLUSH TABLES WITH READ LOCK works with Innodb Tables
March 23, 2012 By 20 Comments
…FLUSH TABLES WITH READ LOCK to temporary make MySQL read only. … | 10219 | root | localhost | dumptest | Query | 324 | Sending data | select count(*) from A,B | 0 | …
Post: How to convert MySQL's SHOW PROFILES into a real profile
February 20, 2012 By 12 Comments
…sample database to demonstrate: mysql> SET profiling=1; mysql> pager cat > /dev/null mysql> SELECT * FROM …| 0.046175 | 26.74 | 1 | 0.0461750000 | | Sending data | 0.018478 | 10.70 | 3 | 0.0061593333 | | … | 0.000014 | 0.01 | 2 | 0.0000070000 | | System lock | 0.000010 | 0.01 | 1 | 0.0000100000 | | …
Post: Write contentions on the query cache
September 5, 2012 By 5 Comments
… 0.000002 | | Sending data | 0.003407 | | Waiting for query cache lock | 0.000003 | | Waiting on query cache mutex | 0.000003 | | Sending data | 0.003515 | …for the lock. Of course, the question was: why did MySQL need so many accesses to the query cache lock? …
Post: How fast is FLUSH TABLES WITH READ LOCK?
April 24, 2010 By 30 Comments
…MySQL backup product. One of the representatives told me that their backup product uses FLUSH TABLES WITH READ LOCK… | 4 | root | localhost | test | Query | 80 | Sending data | select…
Post: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
…Last_errno: 0 Killed: 0 # Query_time: 9.031233 Lock_time: 0.000086 Rows_sent: 0 Rows_examined:…const” MySQL does not count it as access to two tables. In case of “real” access to the data … is worth optimizing ? – see how many rows query sends after group by, distinct and aggregate functions are …
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
… amazing MySQL manual, especially the option and variable…stmt_resetblogpercona.commanual Com_stmt_send_long_datablogpercona.commanual Com_…lock_countblogpercona.commanual memlockblogpercona.commanual min_examined_row_limitblogpercona.commanual myisam_block_sizeblogpercona.commanual myisam_data…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 5 Comments
…Com_stmt_send_long_data to see whenever sending long data feature…mysql> select sum(data_length+index_length) from information_schema.tables where engine=’memory’; +——————————-+ | sum(data…) File system 294352 (82672 + 211680) Lock system 318875832 (318747272 + 128560) Recovery …
