…I configured the server with a 4GB buffer pool. I tested both versions, and as you can see above, MySQL 5.6 outperformed MySQL…varchar(25), C_Address varchar(25), C_City varchar(10), C_Nation varchar(15), C_Region varchar(12), C_Phone varchar(15), C_MktSegment varchar…
Post: Hidden columns of query_review_history table
August 28, 2012 By Leave a Comment
…can use pt-query-digest to process a MySQL slow query … ‘db’ which are not included by default. I will explain how to implement this…_cols values: pct|avt|cnt|sum|min|max|pct_95|stddev|…can manually add and have the following useful columns populated in query_review_history table: * `user_max` varchar…
Post: Using CHAR keys for joins, how much is the overhead ?
June 18, 2007 By 18 Comments
…NOT NULL, KEY `i` (`i`), KEY `j` (`j`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 mysql> select sum(t1.i+t2.j+…. So what if we convert i and j columns to varchar while sticking to utf8 character…I read these results ? CHAR keys are indeed slower for joins compared to integer keys Performance degradation can…
Post: Using GROUP BY WITH ROLLUP for Reporting Performance Optimization
September 17, 2007 By 14 Comments
… NOT NULL, `slack` varchar(50) DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 And I‘m using some … you can fetch on the application side (you can store result in temporary table and run sum() …WITH ROLLUP so I can get grouped result set together with total value for the groups: mysql> select grp,…
