…reading over the manual’s description of how replication filtering rules are processed. There are some informative flowcharts in addition to the…queries in the…the performance being all that fantastic, and I could…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
…locks till the end of the statement and not the end of the transaction. This meant that transaction was not really isolated, because the same query could…the tables was renamed and swapped and that table was the one that is read from by the long running transaction. As the slave tried to execute the…
Post: How fast is FLUSH TABLES WITH READ LOCK?
April 24, 2010 By 30 Comments
…the table is exclusively locked, and all new requests into the system are blocked. Even read queries! Waiting for the lock Before the FLUSH TABLES WITH READ LOCK command can successfully acquire the lock…
Post: Write contentions on the query cache
September 5, 2012 By 5 Comments
…the query myself (a two-table join with a WHERE condition, the…the query cache locks, it was easy to imagine that this query could take ages as soon as there is competition for the lock. Of course, the…
Post: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
…the one in the error log after a crash: “It is possible that mysqld could use up to key_buffer_size + (read…the query cache and the table cache and the size needed for each thread (thread stack, etc)? Those take memory too. The query… user variable and a 100M lock key. Note how long it took to run …
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
…read operations, the number of unique pages the query accessed, the length of time query waited for row locks…the tables involved in the query, probably selecting only the needed columns which could exclude the blob ones. Conclusion The…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…the query and the information mysqlsla outputs about it (execution times, etc), the EXPLAIN plan, and the desired modifications to the query or the table. We explain how…
Post: How FLUSH TABLES WITH READ LOCK works with Innodb Tables
March 23, 2012 By 20 Comments
…TABLES WITH READ LOCK does not work as optimally as you could think it works. Even though with general lock compatibility guidelines Read Lock…table lock priority problem with pending WRITE query blocks any READ queries to execute on the table…
Post: INSERT INTO ... SELECT Performance with Innodb tables.
July 12, 2006 By 22 Comments
…the master should cause the same effect as on the slave. If Innodb would not locking rows in source table other transaction could modify the…how well it performs 
One more thing to keep into account – INSERT … SELECT actually performs read in locking…
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
…how much time (in seconds) it took InnoDB to actually read the data from storage. InnoDB_rec_lock_wait is the time (in seconds) query…the entire buffer pool, because it could take a lot of memory to map all the pages. The inaccuracy grows with the…
