Fenoman / pg_self_query

A tool for receiving the current query (not the top level !!!) for the current PID in order to be able to register it (for example, in the audit subsystem).

Fork info

pg_self_query is based on the pg_query_state extension and is necessary for one purpose - to receive the current (not the top level like current_query()) query for saving it in the audit subsystem (in audit triggers).

The pg_self_query function does not accept any parameters, since it is called only for the current PID. Also, unlike pg_query_state, it does not return anything except the frame number and the query text (previous frame from the current one) for writing to the log. Thus, it is easy to capture a query text, which actually changes the data in tables. So, you can use this function in your audit triggers.

Before using this extension, you must first install the pg_query_state extension, which adds the necessary hooks to intercept query state.

Use cases

Using this module there can help in the following things:

• log (in audit triggers) queries, which actually changes the data in tables

Installation

To install pg_self_query, please apply corresponding patches runtime_explain.patch (or runtime_explain_11.0.patch for PG11) from pg_query_state extension to reqired stable version of PostgreSQL and rebuild PostgreSQL.

Then execute this in the module's directory:

make install USE_PGXS=1

It is essential to restart the PostgreSQL instance. After that, execute the following query in psql:

CREATE EXTENSION pg_self_query;

Done!

Function pg_self_query\

pg_self_query()
	returns TABLE ( frame_number integer,
	                query_text text)

Extract current query state from the current pid.