Re: Query completed in < 1s in PG 9.1 and ~ 700s in PG 9.2

On Wed, Nov 7, 2012 at 5:16 AM, Rodrigo Rosenfeld Rosas
<rr(dot)rosas(at)gmail(dot)com> wrote:
> Em 06-11-2012 19:11, Merlin Moncure escreveu:
>
>> On Tue, Nov 6, 2012 at 1:45 PM, Tom Lane<tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>>
>>> Rodrigo Rosenfeld Rosas<rr(dot)rosas(at)gmail(dot)com> writes:
>>>>
>>>> Em 06-11-2012 17:24, Tom Lane escreveu:
>>>>>
>>>>> Can you put together a self-contained test case to duplicate these
>>>>> results? I'm prepared to believe there's some sort of planner
>>>>> regression involved here, but we'll never find it without a test case.
>>>>
>>>> I'd love to, but I'm afraid I won't have time to do this any time soon.
>>>> Maybe on Sunday. I'll see if I can get a script to generate the database
>>>> on Sunday and hope for it to replicate the issue.
>>>> Would you mind if I coded it using Ruby? (can you run Ruby code in your
>>>> computer?) I mean, for filling with some sample data.
>>>
>>> No objection.
>>
>> hm, wouldn't timing the time to generate a raw EXPLAIN (that is,
>> without ANALYZE) give a rough estimate of planning time? better to
>> rule it out before OP goes to the trouble...
>
> This was a great guess! Congrats, Merlin:

Heh -- that was tom's guess, not mine. What this does is confirm the
planner regression and that elevates the importance of Tom's request
to get sample data so we (he) can fix it.

merlin