Re: Create index concurrently hanging with big table on pgsql 9.3.12

Robert Anderson <ranomail(at)gmail(dot)com> writes:
> There aren't transactions blocking:

> postgres=# SELECT
> postgres-# w.query as waiting_query,
> postgres-# w.pid as waiting_pid,
> postgres-# w.usename as w_user,
> postgres-# l.pid as blocking_pid,
> postgres-# l.usename as blocking_user,
> postgres-# t.schemaname || '.' || t.relname as tablename
> postgres-# FROM pg_stat_activity w
> postgres-# JOIN pg_locks l1 ON (w.pid = l1.pid and not l1.granted)
> postgres-# JOIN pg_locks l2 on (l1.relation = l2.relation and l2.granted)
> postgres-# JOIN pg_stat_activity l ON (l2.pid = l.pid)
> postgres-# JOIN pg_stat_user_tables t ON (l1.relation = t.relid)
> postgres-# WHERE w.waiting;
> waiting_query | waiting_pid | w_user | blocking_pid | blocking_user |
> tablename
> ---------------+-------------+--------+--------------+---------------+-----------
> (0 rows)

This test proves little, because that last JOIN will discard locks on
non-table objects, and what CREATE INDEX CONCURRENTLY would be most
likely to be blocked on is transaction VXIDs. However, since
pg_stat_activity claims that "waiting" is false, probably there isn't
anything in pg_locks. Still, it'd be better to do
"select * from pg_stat_activity where pid = 3990" and be sure.

regards, tom lane