Re: Query Performance SQL Server vs. Postgresql

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hello

2010/11/21 Humair Mohammed <humairm@xxxxxxxxxxx>:
> That was a typo:
> work_mem = 2GB
> shared_buffers = 2GB

ok, then try to decrease a shared_buffers. Maybe a win7 has a some
problem - large a shared buffers are well just for UNIX like systems.
I am thinking so 500 MB is enough

Regards

Pavel Stehule

>> From: pavel.stehule@xxxxxxxxx
>> Date: Sun, 21 Nov 2010 12:38:43 +0100
>> Subject: Re:  Query Performance SQL Server vs. Postgresql
>> To: humairm@xxxxxxxxxxx
>> CC: pgsql-performance@xxxxxxxxxxxxxx
>>
>> 2010/11/21 Humair Mohammed <humairm@xxxxxxxxxxx>:
>> >
>> > 1) OS/Configuration
>> > 64-bit Windows 7 Enterprise with 8G RAM and aÂDual Core 2.67 Ghz Intel
>> > CPU
>> > postgresql-x64-9.0 (PostgreSQL 9.0.1, compiled by Visual C++ build 1500,
>> > 64-bit)
>> > work_mem Â2GB
>> > shared_buffers = 2
>>
>> shared_buffers = 2 ???
>>
>> Regards
>>
>> Pavel Stehule
>>
>>
>> > 2) Dataset
>> > name,pages,tuples,pg_size_pretty
>> > "pivotbad";1870;93496;"15 MB"
>> > "pivotgood";5025;251212;"39 MB"
>> > 3)ÂEXPLAIN (ANALYZE ON, BUFFERS ON)
>> > "Hash Join Â(cost=16212.30..52586.43 rows=92869 width=17) (actual
>> > time=25814.222..32296.765 rows=3163 loops=1)"
>> > " ÂHash Cond: (((pb.id)::text = (pg.id)::text) AND ((pb.question)::text
>> > =
>> > (pg.question)::text))"
>> > " ÂJoin Filter: ((COALESCE(pb.response, 'MISSING'::character
>> > varying))::text
>> > <> (COALESCE(pg.response, 'MISSING'::character varying))::text)"
>> > " ÂBuffers: shared hit=384 read=6511, temp read=6444 written=6318"
>> > " Â-> ÂSeq Scan on pivotbad pb Â(cost=0.00..2804.96 rows=93496
>> > width=134)
>> > (actual time=0.069..37.143 rows=93496 loops=1)"
>> > " Â Â Â ÂBuffers: shared hit=192 read=1678"
>> > " Â-> ÂHash Â(cost=7537.12..7537.12 rows=251212 width=134) (actual
>> > time=24621.752..24621.752 rows=251212 loops=1)"
>> > " Â Â Â ÂBuckets: 1024 ÂBatches: 64 ÂMemory Usage: 650kB"
>> > " Â Â Â ÂBuffers: shared hit=192 read=4833, temp written=4524"
>> > " Â Â Â Â-> ÂSeq Scan on pivotgood pg Â(cost=0.00..7537.12 rows=251212
>> > width=134) (actual time=0.038..117.780 rows=251212 loops=1)"
>> > " Â Â Â Â Â Â ÂBuffers: shared hit=192 read=4833"
>> > "Total runtime: 32297.305 ms"
>> > 4) INDEXES
>> > I can certainly add an index but given the table sizes I am not sure if
>> > that
>> > is a factor. This by no means is a large dataset less than 350,000 rows
>> > in
>> > total and 3 columns. Also this was just a quick dump of data for
>> > comparison
>> > purpose. When I saw the poor performance on the COALESCE, I pointed the
>> > data
>> > load to SQL Server and ran the same query except with the TSQL specific
>> > ISNULL function.
>> >
>

-- 
Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance



[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux