… called long query time. It’s done either with startup parameter –long_query_time=n or by setting MySQL system variable with SET [SESSION|GLOBAL] long_query… with SLAVE STOP and SLAVE START commands. The change in functionality is more of a bugfix than anything else. long_query_time value…
Post: Estimating Replication Capacity
July 20, 2010 By 4 Comments
…queries which load replication the most. It however works only with statement level replication. You need to set long_query…queries MySQL server ran with their times and run mk-query-digest with filter to only check queries from replication thread: mk-query…
Post: Top 5 Wishes for MySQL
June 29, 2007 By 10 Comments
… Queries on MySQL because subqueries optimizer weakness. I’m saying about XA which were released in MySQL 5.0 without consistent work with MySQL… stays where for very long time. For example Query Cache support for Prepared Statements is only fixed in MySQL 5.1 and Most… such little projects suggested by MySQL customers and myself based on long MySQL usage for Web. Later I stopped adding these because I have…
Post: 10+ Ways to Crash or Overload MySQL
November 13, 2007 By 20 Comments
… MySQL. The moment you give someone access to MySQL Server, all MySQL Security guarantees is you can stop … data for each of them using mysql_stmt_send_long_data call – Server buffers such data …Tree The query is internally presented using parse tree inside MySQL which of course depends on query size …
Post: Faster Point In Time Recovery with LVM2 Snaphots and Binary Logs
February 23, 2012 By 3 Comments
…mysql> delete from salaries where emp_no = 10001; Query OK, 17 rows affected (0.15 sec) mysql> drop table salaries; — Ooops! Query…mysql stop Shutting down MySQL (Percona Server)….. [ OK ] [root@sb logs]# umount /mysql/data [root@sb logs]# lvconvert –merge /dev/sb/mysql… a long running ALTER…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
… Oracle folks arrived at this conclusion a long time before the MySQL world started to come around. …cause) relationship between the counter events and the query‘s execution time. Alas, that correlation fools … controversy. But really, it’s time to stop with the bad advice about counter ratios. …
Post: Troubleshooting Relay Log Corruption in MySQL
August 2, 2008 By 7 Comments
… see if relay log corrupted. You could also see malformed queries (with some junk), complaining about event to big etc if… – it could be network (especially if replicating over unreliable long distance networks), MySQL bugs on master or slave, hardware problems and few…_Master_Log_File:Exec_Master_Log_Pos: localhost:(none)> slave stop; Query OK, 0 rows affected (0.00 sec) localhost:(none)> change…
Post: MySQL net_write_timeout vs wait_timeout and protocol notes
July 8, 2007 By 1 Comment
…rather typical for some applications to have long delays between queries. If query is being read or result …partial query received. Result set however comes back in multiple pieces and if you’re using mysql_… reason why you can’t stop fetching for ordinary statements and mysql_free_result will have …
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
…stopped the MySQL 5.6 server, rebooted and verified again. Same issue. This was very different from MySQL…. Innodb_old_blocks_time controls how long a page must be on the …query with only one join, I’ve tested performance of the query with the join in both directions. Explain for query Q1.1: mysql…
Post: Percona's Commitments to MySQL Users
November 5, 2010 By 10 Comments
… MySQL over the years. Many of us at Percona came from the original MySQL team. We know that it took a decade-long… slowdowns over the last few years. This era is over. MySQL has never progressed so rapidly towards better features, better performance… tools for monitoring, query analysis, replication management, and other capabilities. If you’re worried about Oracle making MySQL closed-source, stop worrying. It…
