Re: loading increase into huge table with 50.000.000 records

Hi Larry,

Do you run vacuum and analyze frequently?
Did you check PowerPostgresql.com for hints about PostgreSQL tuning?
<http://www.powerpostgresql.com/Docs/>

You can increase wal_buffers, checkpoint_segments and checkpoint_timeout
much higher.

Here is a sample which works for me.
wal_buffers = 128
checkpoint_segments = 256
checkpoint_timeout = 3600

Cheers
Sven.

nuggets72(at)free(dot)fr schrieb:
> Hello,
> Sorry for my poor english,
>
> My problem :
>
> I meet some performance problem during load increase.
>
> massive update of 50.000.000 records and 2.000.000 insert with a weekly
> frequency in a huge table (+50.000.000 records, ten fields, 12 Go on hard disk)
>
> current performance obtained : 120 records / s
> At the beginning, I got a better speed : 1400 records/s
>
>
> CPU : bi xeon 2.40GHz (cache de 512KB)
> postgresql version : 8.1.4
> OS : debian Linux sa 2.6.17-mm2
> Hard disk scsi U320 with scsi card U160 on software RAID 1
> Memory : only 1 Go at this time.
>
>
> My database contains less than ten tables. But the main table takes more than 12
> Go on harddisk. This table has got ten text records and two date records.
>
> I use few connection on this database.
>
> I try many ideas :
> - put severals thousands operations into transaction (with BEGIN and COMMIT)
> - modify parameters in postgres.conf like
> shared_buffers (several tests with 30000 50000 75000)
> fsync = off
> checkpoint_segments = 10 (several tests with 20 - 30)
> checkpoint_timeout = 1000 (30-1800)
> stats_start_collector = off
>
> unfortunately, I can't use another disk for pg_xlog file.
>
>
> But I did not obtain a convincing result
>
>
>
> My program does some resquest quite simple.
> It does some
> UPDATE table set dat_update=current_date where id=XXXX ;
> And if not found
> id does some
> insert into table
>
>
> My sysadmin tells me write/read on hard disk aren't the pb (see with iostat)
>
>
> Have you got some idea to increase performance for my problem ?
>
> Thanks.
>
> Larry.
>
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Sven Geisler <sgeisler(at)aeccom(dot)com> Tel +49.30.5362.1627 Fax .1638
Senior Developer, AEC/communications GmbH Berlin, Germany