Re: New dot releases

Hi,

On Fri, 16 Sep 2005, Michael Fuhr wrote:

> On Fri, Sep 16, 2005 at 09:28:39AM -0600, Michael Fuhr wrote:
>> FWIW, I have a Solaris 9/sparc box with gcc 3.4.2 (same setup as
>> gerbil) and have no problems with REL7_2_STABLE through HEAD. I'll
>> test REL8_0_STABLE with gerbil's configure options when I get a
>> chance.
>
> I just built REL8_0_STABLE with the following configure options
> (same as gerbil):
>
> ./configure --enable-cassert --enable-debug --enable-nls \
> --enable-integer-datetimes --with-perl --with-python \
> --with-openssl --with-pgport=5682
>
> gmake check returned the following:
>
> ======================
> All 96 tests passed.
> ======================

So no need to hold the new dot releases? :)

I want to work on new RPM sets and don't want to apply countless
patches... :)

Regards,
--
Devrim GUNDUZ
Kivi Bilişim Teknolojileri - http://www.kivi.com.tr
devrim~gunduz.org, devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr
http://www.gunduz.org
>From pgsql-hackers-owner(at)postgresql(dot)org Mon Sep 19 11:27:58 2005
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Message-ID: <432ECAE2(dot)7070805(at)cybertec(dot)at>
Date: Mon, 19 Sep 2005 16:27:46 +0200
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To: pgsql-hackers(at)postgresql(dot)org
Subject: DISTINCT vs. GROUP BY
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I was wondering whether it is possible to teach the planner to handle
DISTINCT in a more efficient way:

em=# explain select distinct lastname from import.testtest;
QUERY PLAN
--------------------------------------------------------------------------------
Unique (cost=2647377.45..2709467.70 rows=1 width=7)
-> Sort (cost=2647377.45..2678422.58 rows=12418051 width=7)
Sort Key: lastname
-> Seq Scan on testtest (cost=0.00..370082.51 rows=12418051
width=7)
(4 Zeilen)

Isn't it possible to perform the same operation using a HashAggregate?
We have seen that a GROUP BY workaround is usually a lot faster than
sort->unique - at least when work_mem is large enough.

best regards,

hans

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