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.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services