PGPool Frequent Queries
I don't think these are issued by PGPool.  I think they are instigated by your application (which I am guessing is written in PHP and running over some sort of ORM).

The first entry is DEALLOCATE which means effectively to tell the server to free up memory from a prepared statement.  These look like they are issued through some PDO module.

The second and third queries look like they are ORM-related mapping queries.  Your application is probably unware that these queries are being issued by the framework it is running on, but these queries only make sense really in an ORM or similar environment.