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

2016-02-17 3:43 GMT+01:00 Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>:

> 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?
>

I hope, so I propose this idea. First time I wanted talk about the idea.
Next step is the talk about format.

>
> What I think would be far more useful is adding lock wait time info to
> pg_stat_statements and maybe pg_stat_*_tables.

If we can enhance primary log, auto_explain, then we can do same with
pg_stat_statements.

lock statistics in table or database level would be great - it is good
simple indicator about application health, but it is for another proposal
(and patch). I can propose it, or I can collaborate on it with pleasure.

Regards

Pavel

>
> --
> Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
> Experts in Analytics, Data Architecture and PostgreSQL
> Data in Trouble? Get it in Treble! http://BlueTreble.com
>