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18 March 2012 at 4:17am
in our latest SS project we having some performance problems with the mysql db server.
So now i need to find the bottleneck in the database server.
The configuration of the mysql server is not optimal, but i think i found a problem that comes from SS.
I am no mysql expert, so please let me know if i am wrong.
When you define something like :
static $db = array(..., 'Description' => 'Text', 'Comments' => 'HTMLText');
the columns for 'Descrition' and 'Comments' are created as 'mediumtext'
This is the default behaviour
If you are making queries that uses this table, i think mysql will slow down because of the mediumtext colums.
The reason is (i think) msql is using temporary tables internal. If tinytext/mediumtext/blob colums exists, mysql cannot create the tmp tables in memory but needs to create them on a harddisk.
Temporary tables on harddisk are of course slower than creating them in memory.
The mysql status will show you then a high value for "Created_tmp_disk_tables"
Can i relpace any mediumtext column with Varchar(1000) ?
Has anyone ever done some mysql performance testing concerning this "problem".
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