[pgpool-general: 4620] Re: Long running temp table checks

[Tatsuo Ishii]

> I've noticed strange long running queries on our PostgreSQL (9.4.4) running
> with  PgPool-II (3.4.3). Quite frequently there are queries like
> 
> SELECT count(*) FROM pg_class AS c, pg_namespace AS n WHERE c.relname =
> <tablename> AND c.relnamespace = n.oid AND n.nspname ~ '^pg_temp_'
> 
> in the pg_stat_activity view. I assume, these are PgPool-II checks to
> identify temp tables on the master (which can be enabled/disabled by
> check_temp_table config switch). The strange thing about it is, that
> sometimes the query hangs in the view (in 'active' state) well over 10
> minutes, without being held by lock or whatever.
> 
> I've checked the running postgres process with strace and it is in the
> recvfrom() on the socket with the PgPool-II connection.
> Running the query localy takes milliseconds (as expected).
> 
> Have anyone encountered such behaviour, or is it to be expected and I'm
> misunderstanding something?

Probably it's a false alarm. See the FAQ for more details.

pgpool.net/mediawiki/index.php/FAQ#When_I_check_pg_stat_activity_view.2C_I_see_a_query_like_.22SELECT_count.28.2A.29_FROM_pg_catalog.pg_class_AS_c_WHERE_c.oid_.3D_pgpool_regclass.28.27pgbench_accounts.27.29_AND_c.relpersistence_.3D_.27u.27.22_in_active_state_for_very_long_time._Why.3F

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp