… amazing MySQL manual, especially the option and …Com_create_udfblogpercona.commanual Com_create_userblogpercona.commanual Com_create_viewblogpercona.commanual Com_dealloc_sqlblogpercona.commanual Com_deleteblogpercona.commanual Com_delete_multiblogpercona.commanual Com_doblogpercona.commanual Com…
Post: How to recover deleted rows from an InnoDB Tablespace
February 20, 2012 By 4 Comments
… to delete the records of the employee 10008 from the table “salaries”. After the “accidental” deletion of rows you should stop MySQL, take… information about row format on the following link: http://dev.mysql.com/doc/refman/5.5/en/innodb-physical-record.html You… the salaries.recovery you can find lot of deleted rows, not only rows deleted accidentally. You should manually find the data you…
Post: How to create/restore a slave using GTID replication in MySQL 5.6
February 8, 2013 By 7 Comments
… internally because there are many documents about that: http://dev.mysql.com/doc/refman/5.6/en/replication-gtids-concepts.html One… GTID is the master and set it on the slave. MySQL keeps two global variables with GTID numbers on it: gtid…: it contains a representation of the set of all transactions deleted from the binary log So now, the process is the…
Post: STOP: DELETE IGNORE on Tables with Foreign Keys Can Break Replication
February 2, 2012 By 1 Comment
…) An expected behavior for DELETE IGNORE is that if the statement fails to delete all rows, none should be deleted at all, after… 5.5, MySQL will stop deleting rows if it encounters constraint errors. To demonstrate on 5.5.17: I delete some rows from… query in this example will be considered STATEMENT (http://dev.mysql.com/doc/refman/5.1/en/binary-log-mixed.html) thus…
Post: Filling the tmp partition with persistent connections
August 6, 2012 By 14 Comments
… files has MySQL opened: # lsof -p 6112|grep ML mysqld 6112 root 38u REG 7,0 106594304 18 /tmp/MLjw4ecJ (deleted) mysqld… REG 7,0 62390272 26 /tmp/ML19sFCA (deleted) There are lot of files in deleted status that are filling the partition. The… opened a bug report to follow this issue: http://bugs.mysql.com/bug.php?id=66237
Post: InnoDB's gap locks
March 27, 2012 By 15 Comments
… a SELECT. They only occur if you do UPDATE or DELETE or SELECT FOR UPDATE. InnoDB provides REPEATABLE READ for read… | | 25 | | 30 | +——+ Start a transaction and delete the record 25: transaction1 > START TRANSACTION; transaction1 > DELETE FROM t WHERE age=25; At this… source of information: http://dev.mysql.com/doc/refman/5.1/en/innodb-locks-set.html. Conclusion MySQL uses REPEATABLE READ as the…
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
… great feature called “Query Cache” which is quite helpful for MySQL Performance optimization tasks but there are number of things you… comes from modification statements which you can calculate by (Com_insert+Com_delete+Com_update+Com_replace)/Qcache_hits . These are some numbers you can…
Post: Introducing tpce-like workload for MySQL
February 8, 2010 By 6 Comments
…performance research and/or compare with available Storage Engines for MySQL. The workload in tpce is quite different from tpcc. …details, there is stats for 10 seconds: | Com_select | 46272 | | Com_update | 5214 | | Com_delete | 385 | | Com_insert | 3468 | | Com_commit | 5404 | The result is quite…
Post: SQL Injection Questions Followup
July 26, 2012 By 2 Comments
… SQL expressions instead of in application code. See http://dev.mysql.com/doc/refman/5.5/en/string-literals.html for more… moves too much computation load onto their database server. Their MySQL server became CPU-bound, while their multiple PHP application servers… all these cases. Andrey M. also asked: Q: Should I delete all unsafe sentences from user input before I store the…
Post: Logging Foreign Key errors
September 27, 2012 By Leave a Comment
… error. Let’s see the explanation with perror: # perror 150 MySQL error code 150: Foreign key constraint is incorrectly formed Still… is. 4- Let’s check what the tool has logged: mysql> select * from test.foreign_key_errors\G *************************** 1. row *************************** ts: 2012…” (“emp_no”) ON DELETE CASCADE The index in the foreign key in table is “PRIMARY” See http://dev.mysql.com/doc/refman/5…
