postgres=# show shared_preload_libraries
;
             shared_preload_libraries
---------------------------------------------------
 timescaledb, pg_stat_statements, pg_wait_sampling
(1 row)

postgres=# \dx
                                         List of installed extensions
        Name        | Version |   Schema   |                            Description
--------------------+---------+------------+-------------------------------------------------------------------
 pg_stat_statements | 1.6     | public     | track execution statistics of all SQL statements executed
 pg_wait_sampling   | 1.1     | public     | sampling based statistics of wait events
 plpgsql            | 1.0     | pg_catalog | PL/pgSQL procedural language
 timescaledb        | 1.5.0   | public     | Enables scalable inserts and complex queries for time-series data
(4 rows)

postgres=# show pg_wait_sampling.profile_queries ;
 pg_wait_sampling.profile_queries
----------------------------------
 on
(1 row)

begin;
truncate a;

insert into a values (1)

postgres=# select * from pg_wait_sampling_current where event = 'relation';
 pid | event_type |  event   | queryid
-----+------------+----------+---------
 634 | Lock       | relation |       0
(1 row)