Re: Some queries starting to hang - Mailing list pgsql-performance

From Craig A. James
Subject Re: Some queries starting to hang
Date
Msg-id 4485BF25.4080701@modgraph-usa.com
Whole thread Raw
In response to Re: Some queries starting to hang  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-performance
Simon Riggs wrote:
>>Well, it's a big query.  If it ought to take a second or two, and
>>instead is taking an hour or two (1800 times the expected runtime), that
>>might be close enough to "never" to exhaust Chris' patience.  Besides,
>>we don't know whether the 1800 might itself be an underestimate (too bad
>>Chris didn't provide EXPLAIN ANALYZE results).
>
> This is a good example of a case where the inefficiency of EXPLAIN
> ANALYZE would be a contributory factor to it not actually being
> available for diagnosing a problem.

This is a frustration I have, but Simon expressed it much more concisely.  The first question one gets in this forum
is,"did you run EXPLAIN ANALYZE?"  But if EXPLAIN ANALYZE never finishes, you can't get the information you need to
diagnosethe problem.  Simon's proposal, 

> e.g. EXPLAIN ANALYZE ERRLIMIT 10 SELECT ...

or something similar, would be a big help.  I.e. "If you can't finish in a reasonable time, at least tell me as much as
youcan." 

Craig

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