pg_query_rewrite

pg_query_rewrite : Rewrite SQL statements with a PostgreSQL ProcessUtility hook

Overview

Packages

Source

pig build pkg pg_query_rewrite;		# build rpm/deb

Install

Make sure PGDG and PIGSTY repo available:

pig repo add pgsql -u   # add both repo and update cache

Install this extension with pig:

pig install pg_query_rewrite;		# install via package name, for the active PG version

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

Config this extension to shared_preload_libraries:

shared_preload_libraries = 'pg_query_rewrite';

Create this extension with:

CREATE EXTENSION pg_query_rewrite;

Usage

• GitHub Repo: pierreforstmann/pg_query_rewrite
• README: pierreforstmann/pg_query_rewrite/blob/master/README.md

pg_query_rewrite is a PostgreSQL extension that translates an exact source SQL statement into another predefined SQL statement. It must be loaded at server level with shared_preload_libraries, then installed in each database.

The README shows the extension as a simple statement rewrite engine backed by shared-memory rules.

Setup

shared_preload_libraries = 'pg_query_rewrite'
pg_query_rewrite.max_rules = 10

CREATE EXTENSION pg_query_rewrite;

The README says the extension has been successfully tested with PostgreSQL 9.5 through 18.

Managing Rules

Use the helper functions to manage translations:

SELECT pgqr_add_rule('select 10;', 'select 11;');
SELECT pgqr_remove_rule('select 10;');
SELECT pgqr_truncate();
SELECT pgqr_rules();

The example in the README rewrites select 10; to select 11; and then shows the rule list after insertion.

Behavior

• Matching is exact and sensitive to case, spaces, and semicolons.
• Parameterized SQL statements are not supported.
• The maximum SQL statement length is hard-coded at 32K.
• Rules live only in shared memory; the extension does not persist settings on its own.
• pg_query_rewrite.max_rules caps the number of SQL statements that can be translated and defaults to 10 when unset.

Scope

The upstream README is sufficient here: it covers purpose, server-level loading, rule management, a concrete rewrite example, and the main limitations. No separate docs page or homepage was needed.