On 26/09/2018 23:48, Peter Eisentraut wrote:
> On 26/09/2018 17:54, Alvaro Herrera wrote:
>> What could be the use for the transaction timestamp? I think one of the
>> most important uses (at least in pg_stat_activity) is to verify that
>> transactions are not taking excessively long time to complete; that's
>> known to cause all sorts of trouble in Postgres, and probably other
>> DBMSs too. If we don't accurately measure what it really is, and
>> instead keep the compatibility behavior, we risk panicking people
>> because they think some transaction has been running for a long time
>> when in reality it's just a very long procedure which commits frequently
>> enough not to be a problem.
>
> That's certainly a good argument. Note that if we implemented that the
> transaction timestamp is advanced inside procedures, that would also
> mean that the transaction timestamp as observed in pg_stat_activity
> would move during VACUUM, for example. That might or might not be
> desirable.
Attached is a rough implementation.
I'd be mildly in favor of doing this, but we have mentioned tradeoffs in
this thread.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
