Re: Question about ALTER TABLE DROP CONSTRAINT on 9.1 -- psql crashes

Craig Ringer <ringerc@ringerc.id.au> writes:
> On 08/10/2012 10:06 AM, Tom Lane wrote:
>> That sure sounds like the source of your problem.  It might be sane if
>> it killed only processes that *had been idle* for at least three
>> seconds, but I'm not sure there is any easy way to determine that ...

> wouldn't:

> select * from pg_stat_activity
> where current_query = '<IDLE> in transaction'
> AND query_start < current_timestamp - INTERVAL '3 seconds';

> do it?

No, that would find sessions that were idle and whose last command
started at least 3 seconds ago.  But it might have completed only
microseconds ago.  The symptoms Greg is describing are consistent
with this kill script running during a short interval between his
index-build command and his COMMIT.

As of 9.2 there's a "state_change" timestamp column in pg_stat_activity
that would provide a safer check, but it's not in existing releases ...

            regards, tom lane