From: Tom Lane <tgl@sss.pgh.pa.us>
To: Claudio Freire <klaussfreire@gmail.com>
Cc: Josh Berkus <josh@agliodbs.com>
Cc: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Shouldn't we have a way to avoid "risky" plans?
Date: Wed, 23 Mar 2011 17:00:04 -0400
Message-ID: <4286.1300914004@sss.pgh.pa.us> (raw)
In-Reply-To: <AANLkTi=RXUSrCxqz3=BkAiixuenu2gf-K+W15Wz4McXH@mail.gmail.com>
References: <4D8A29F2.9080105@agliodbs.com>
<AANLkTi=GAz7gFBCoXQeRDN3PUA0fXxRyP_=DxS4Y1tJU@mail.gmail.com>
<4D8A581D.5080704@agliodbs.com>
<AANLkTi=RXUSrCxqz3=BkAiixuenu2gf-K+W15Wz4McXH@mail.gmail.com>
Claudio Freire <klaussfreire@gmail.com> writes:
> On Wed, Mar 23, 2011 at 5:29 PM, Josh Berkus <josh@agliodbs.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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, klaussfreire@gmail.com, josh@agliodbs.com
Subject: Re: Shouldn't we have a way to avoid "risky" plans?
In-Reply-To: <4286.1300914004@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox