Slow query on information_schema.tables

Question

I run a set of self-developed applications on a typical shared hosting service offering. I moved from a static configured table list of allowed tables to one based on a lis

Answer 1

For those who may want a hack with a minor drawback: http://www.mysqlperformanceblog.com/2011/12/23/solving-information_schema-slowness/

What it does is it disable some stats that get updated if you query the schema, more information here: http://dev.mysql.com/doc/refman/5.1/en/innodb-parameters.html#sysvar_innodb_stats_on_metadata

And to make things easier for lazy bums who don't want to read, you only need to make a change to a setting:

innodb_stats_on_metadata=0

You can do this in the config file or dynamically:

mysql> set global innodb_stats_on_metadata=0;

Answer 2

The information schema is not optimized, there are no indexes, just tables with metadata, and usually, when you run SELECT from the schema, it opens and reads files.

Have a look at this article - Optimizing INFORMATION_SCHEMA Queries; in some cases it will help you.