| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
| Cc: | Josh Berkus <josh(at)agliodbs(dot)com>, postgres performance list <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Shouldn't we have a way to avoid "risky" plans? |
| Date: | 2011-03-23 21:00:04 |
| Message-ID: | 4286.1300914004@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
Claudio Freire <klaussfreire(at)gmail(dot)com> writes:
> On Wed, Mar 23, 2011 at 5:29 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>> On 3/23/11 10:35 AM, Claudio Freire wrote:
>>> * consider plan bailout: execute a tempting plan, if it takes too
>>> long or its effective cost raises well above the expected cost, bail
>>> to a safer plan
>> That would actually solve this particular case. It would still require
>> us to have some definition of "safer" though.
> In my head, safer = better worst-case performance.
If the planner starts operating on the basis of worst case rather than
expected-case performance, the complaints will be far more numerous than
they are today.
regards, tom lane
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