rails/rails — pull request #16421 by tsukasaoishi (2014-08-07 14:11:33+00:00)
Title: Tables existence check query is executed in large quantities

When Rails starts, tables existence check query is executed number of models.
In case of mysql,

SHOW TABLES LIKE 'table1';
SHOW TABLES LIKE 'table2';
SHOW TABLES LIKE 'table3';
...
SHOW TABLES LIKE 'table999';

Add process to get the names of all tables by one query.