Re: proposal: enhancing slow query log, and autoexplain log about waiting on lock before query exec time

On 2/14/16 11:24 AM, Pavel Stehule wrote:
> > We have a patch, that inject logs about the time waiting on locks before
> > query execution. This feature helps us lot of, and I hope, it can be
> > generally useful.
>
> Doesn't log_lock_waits cover that territory already?
>
> It does. But It creates different log entry - and can be hard to join
> slow query with log entry sometimes lot of lines before. This proposal
> is about taking important information comfortably - and log parsing and
> processing is simpler.

I'm all for anything that improves visibility into locking, but it seems
like this is more a band-aid than a fix. Certainly any real analysis of
logfiles means you're stuck with something like pgBadger. If this would
significantly simply pgBadger's job then great, but I don't think that's
the case.

What would be useful logging-wise is if the log line for the query
itself could contain lock wait time, but that doesn't sound like what
you're proposing?

What I think would be far more useful is adding lock wait time info to
pg_stat_statements and maybe pg_stat_*_tables.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
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