pgpool_regclass

pgpool : replacement for regclass

Overview

Packages

Source

Install

Make sure PGDG repo available:

pig repo add pgdg -u    # add pgdg repo and update cache

Install this extension with pig:

pig install pgpool;		# install via package name, for the active PG version
pig install pgpool_regclass;		# install by extension name, for the current active PG version

pig install pgpool_regclass -v 18;   # install for PG 18
pig install pgpool_regclass -v 17;   # install for PG 17
pig install pgpool_regclass -v 16;   # install for PG 16
pig install pgpool_regclass -v 15;   # install for PG 15
pig install pgpool_regclass -v 14;   # install for PG 14

Create this extension with:

CREATE EXTENSION pgpool_regclass;

Usage

pgpool_regclass: replacement for regclass

The pgpool_regclass extension provides a replacement regclass function used internally by Pgpool-II to handle relation name resolution across multiple backends.

Function

-- Resolve a relation name to its OID, similar to PostgreSQL's regclass cast
SELECT pgpool_regclass('my_table');
SELECT pgpool_regclass('my_schema.my_table');

Purpose

In standard PostgreSQL, casting a string to regclass (e.g., 'my_table'::regclass) resolves the relation name to an OID. However, Pgpool-II needs to determine whether a SQL statement references a temporary table or a regular table to route queries correctly.

The pgpool_regclass function provides this resolution capability as a regular function call rather than a type cast, allowing Pgpool-II to:

• Determine if a referenced table exists on the backend
• Distinguish temporary tables from permanent tables for proper query routing
• Handle schema-qualified table names correctly across pooled connections

Notes

• This extension is primarily used internally by Pgpool-II and is not typically called directly by applications
• It should be installed on all PostgreSQL backend nodes managed by Pgpool-II
• For Pgpool-II 3.0+, this function helps with the check_temp_table feature