Re: Some queries starting to hang

Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> You mentioned it would be good if the OP had delivered an EXPLAIN
> ANALYZE; I agree(d). The lack of EXPLAIN ANALYZE is frequently because
> you can't get them to run to completion - more so when the query you
> wish to analyze doesn't appear to complete either.

Well, he could have shown EXPLAIN ANALYZE for the server that was
managing to run the query in a reasonable amount of time.

> The idea I just had was: why do we need EXPLAIN ANALYZE to run to
> completion? In severe cases like this thread, we might be able to
> discover the root cause by a *partial* execution of the plan, as long as
> it was properly instrumented. That way, the OP might have been able to
> discover the root cause himself...

I don't think that helps, as it just replaces one uncertainty by
another: how far did the EXPLAIN really get towards completion of the
plan? You still don't have any hard data.

regards, tom lane