| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Mladen Gogala <mladen(dot)gogala(at)vmsinfo(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: anti-join chosen even when slower than old plan |
| Date: | 2011-01-20 14:19:00 |
| Message-ID: | AANLkTi=OYC2dN1SkaSY5AEyOVd4Zu-YPTgW-YKV=+xsj@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On Thu, Jan 20, 2011 at 4:17 AM, Cédric Villemain
<cedric(dot)villemain(dot)debian(at)gmail(dot)com> wrote:
>>> I think his point is that we already have a proven formula
>>> (Mackert-Lohmann) and shouldn't be inventing a new one out of thin air.
>>> The problem is to figure out what numbers to apply the M-L formula to.
>>>
>>> I've been thinking that we ought to try to use it in the context of the
>>> query as a whole rather than for individual table scans; the current
>>> usage already has some of that flavor but we haven't taken it to the
>>> logical conclusion.
>>
>> Is there a TODO here?
>
> it looks like, yes.
"Modify the planner to better estimate caching effects"?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Andy Colson | 2011-01-20 14:48:53 | Re: Migrating to Postgresql and new hardware |
| Previous Message | Cédric Villemain | 2011-01-20 09:17:08 | Re: anti-join chosen even when slower than old plan |