…sessions have created which temporary tables (both in memory and not): mysql> select * from information_schema.global_temporary_tables \G *************************** 1. row *************************** SESSION…
Post: InnoDB's gap locks
March 27, 2012 By 15 Comments
… read-only SELECT, but it behaves as if you use READ COMMITTED for all write queries, in spite of… that the second one is a global variable that affects all sessions and needs a server restart to …: http://dev.mysql.com/doc/refman/5.1/en/innodb-locks-set.html. Conclusion MySQL uses REPEATABLE READ as …
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…session_cache_modeblogpercona.commanual Ssl_session_cache_overflowsblogpercona.commanual Ssl_session_cache_sizeblogpercona.commanual Ssl_session_cache_timeoutsblogpercona.commanual Ssl_sessions_reusedblogpercona.commanual Ssl_used_session…
Post: Can we improve MySQL variable handling ?
February 18, 2012 By 8 Comments
… in set (0.00 sec) This could be used as technique to detect the value for DEFAULT variables for SESSION variables, yet for some GLOBAL variables… be good idea to extend SELECT syntax to ease querying of variable global value Right now I can select: mysql> select @@global.sort_buffer_size…
Post: MySQL Session variables and Hints
December 28, 2006 By 2 Comments
…tune execution of particular query. First is MySQL Hints, such as SQL_BIG_RESULT, STRAIGHT_… example SELECT STRAIGHT_JOIN * FROM A FORCE INDEX(A) JOIN B The other part is session variable….query. I noticed in production hints are used much more frequently than setting session variables for given query…
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 63 Comments
… 60 stable. We can also get query_cache_ttl as session variable, which is very helpful for connections opened to the slaves… applications in MySQL have very large number of queries doing updates through primary key and use primary key for selects. I believe in such cases we can track it in a more granular fashion…
Post: PHP Sessions - Files vs Database Based
March 27, 2007 By 38 Comments
…session data damaged because you will have lost session variables update from one of the script, in…use Innodb tables for your session storage you can start transaction on the session start and use SELECT … FOR UPDATE to lock the session row in the session…
Post: How Percona diagnoses MySQL server stalls
March 3, 2011 By 6 Comments
…MySQL (if necessary, put a password into .my.cnf, or in the MYSQLOPTIONS variable). Now you can simply start running bin/stalk in a screen session…stored in /root/collected/ by default. Use the “…_10_03 Select a timestamp from…
Post: MySQL Users Conference Presentation Proposals
October 24, 2007 By 12 Comments
…select platform for MySQL. Performance comparison of MySQL 5.0, MySQL 5.1 and MySQL 6.0 Come to see how performance of MySQL…MySQL Variables Tuning This session takes practical approach to MySQL variable tuning. Instead of giving you theoretical guesses on what would be right variable…
Comment: Using VIEW to reduce number of tables used
October 5, 2007 By 12 Comments
…about using session variables to achive the effect with inserts and reduce… AS SELECT * FROM posts WHERE owner_id = @owner_id;[/CODE] But, yes, variables can’t be used inside a view definition. I have [URL=http://omelnyk.net/blog/2007/06/18/using-views-with-variables-in-mysql…
