Re: [PATCH] Add last_executed timestamp to pg_stat_statements

Re: Pavlo Golub
> How about
> TimestampTz stmt_end = TimestampTzPlusMilliseconds(
> GetCurrentStatementStartTimestamp(),
> (int64) total_time
> );
> We have total_time as an argument already! No kernel calls, sweet and easy!

Cool idea!

Re: Sami Imseih
> I think it's better because last_execution_start is already a known
> timestamp in pg_stat_activity.query_start and some tool that finds a
> long running query in pg_stat_activity, knowing the
> query_start they could then go look it up in pg_stat_statements.

That only works if a) the query was not yet overwritten in
pg_stat_activity and b) neither in pg_stat_statements. Optimizing for
that use case seems pretty narrow.

> What I'm really getting at is separating these fields will open up
> more use cases, IMO.

Generally, I think pgss should have cumulative statistics, and less
about individual executions, so I'm not really sure what practical
problem "last start" and "last runtime" would solve. The
last_stats_update column we are talking about here is different in the
sense that it's not about an individual execution, but infrastructure
for retrieving the stats sensibly.

Christoph