pg_stat_statements empty with administrator user and unusable for other users

Question

I have an issue with pg_stat_statements, the extension is installed and enabled on the database, was working for a long time, however it now seems that it has crashed.

portaldb=> SELECT * FROM pg_available_extensions WHERE name = 'pg_stat_statements';
        name        | default_version | installed_version |                          comment                          
--------------------+-----------------+-------------------+-----------------------------------------------------------
 pg_stat_statements | 1.4             | 1.4               | track execution statistics of all SQL statements executed
(1 row)

portaldb=# SELECT * FROM pg_available_extension_versions WHERE name = 'pg_stat_statements';
        name        | version | installed | superuser | relocatable | schema | requires |                          comment                          
--------------------+---------+-----------+-----------+-------------+--------+----------+-----------------------------------------------------------
 pg_stat_statements | 1.4     | t         | t         | t           |        |          | track execution statistics of all SQL statements executed
(1 row)

The extension is enabled on the portaldb database

portaldb=> create extension pg_stat_statements;                                    
ERROR:  extension "pg_stat_statements" already exists

I was considering removing it and then recreating it but I feel a bit scared to apply a cascade drop, because this is a big e-commerce portal and we don't want lose data or cause any outage.

portaldb=# DROP EXTENSION pg_stat_statements;                        
ERROR:  cannot drop extension pg_stat_statements because other objects depend on it
DETAIL:  function get_pg_stats() depends on type pg_stat_statements
HINT:  Use DROP ... CASCADE to drop the dependent objects too.

If I try with the user that manages the database we receive the following error:

portaldb=> SELECT * FROM pg_stat_statements ORDER BY total_time DESC;
ERROR:  relation "pg_stat_statements" does not exist
LINE 1: SELECT * FROM pg_stat_statements ORDER BY total_time DESC;

However if we execute the same query under root (postgres user) we receive a blank output.

portaldb=# SELECT * FROM pg_stat_statements ORDER BY total_time DESC;
 userid | dbid  |  queryid   |

portaldb=#

root@Serv01:~# cat /app/postgres/postgresql.conf | grep shared_preload_libraries
shared_preload_libraries = 'pg_stat_statements'
root@Serv01:~# cat /app/postgres/postgresql.conf | grep pg_stat_statements.
shared_preload_libraries = 'pg_stat_statements'
pg_stat_statements.max = 10000
pg_stat_statements.track = all
pg_stat_statements.track_utility = on

Has anyone else come across this situation? I Googled but I didn't find any related case.

Answer 1

I found the solution, when we enable the extension on database creates a function seems that someone remove the function (there are many users on with database user), we recreate it and now works properly, thank for your help Vérace.

portaldb=> \df+

                                                                                                                                                                                              List of functions
   Schema    |           Name           | Result data type |                                                                                                                                                                
                                                                                                                                                          Argument data types                                               

                                                |  Type  | Volatility | Parallel |  Owner   | Security |  Access privileges  | Language |       Source code        | Description 
-------------+--------------------------+------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------+--------+------------+----------+----------+----------+---------------------+----------+--------------------------+-------------
 portaldb | pg_stat_statements       | SETOF record     | showtext boolean, OUT userid oid, OUT dbid oid, OUT queryid bigint, OUT query text, OUT calls bigint, OUT total_time double precision, OUT min_time double prec
ision, OUT max_time double precision, OUT mean_time double precision, OUT stddev_time double precision, OUT rows bigint, OUT shared_blks_hit bigint, OUT shared_blks_read bigint, OUT shared_blks_dirtied bigint, OUT shared
_blks_written bigint, OUT local_blks_hit bigint, OUT local_blks_read bigint, OUT local_blks_dirtied bigint, OUT local_blks_written bigint, OUT temp_blks_read bigint, OUT temp_blks_written bigint, OUT blk_read_time double
 precision, OUT blk_write_time double precision | normal | volatile   | safe     | postgres | invoker  |                     | c        | pg_stat_statements_1_3   | 
 portaldb | pg_stat_statements_reset | void             |                                                                                                                                                                


                                                | normal | volatile   | safe     | postgres | invoker  | postgres=X/postgres | c        | pg_stat_statements_reset |