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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