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Re: Looking for tips

From: Oliver Crosby <ryusei(at)gmail(dot)com>
To: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Looking for tips
Date: 2005-07-19 18:21:22
Message-ID: 1efd553a050719112126b8d981@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
I was hoping to start with tuning postgres to match the hardware, but
in any case..

The queries are all simple insert or select statements on single tables.
Eg. select x from table where y=?; or insert into table (a, b, c)
values (?, ?, ?);
In the case of selects where it's a large table, there's an index on
the column being searched, so in terms of the example above, x is
either a pkey column or other related field, and y is a non-pkey
column.

I'm not sure what you mean by structure.

I tried explain analyse on the individual queries, but I'm not sure
what can be done to manipulate them when they don't do much.

My test environment has about 100k - 300k rows in each table, and for
production I'm expecting this to be in the order of 1M+.

The OS is Redhat Enterprise 3.

I'm using a time command when I call the scripts to get a total
running time from start to finish.

I don't know what we have for RAID, but I suspect it's just a single
10k or 15k rpm hdd.
------------------------------------------------------------------------------------------------------------------------
I'll try your recommendations for shared_buffers and
effective_cache_size. Thanks John!

We're trying to improve performance on a log processing script to the
point where it can be run as close as possible to realtime. A lot of
what gets inserted depends on what's already in the db, and it runs
item-by-item... so unfortunately I can't take advantage of copy.

We tried dropping indices, copying data in, then rebuilding. It works
great for a bulk import, but the processing script went a lot slower
without them. (Each insert is preceeded by a local cache check and
then a db search to see if an ID already exists for an item.)

We have no foreign keys at the moment. Would they help?


On 7/19/05, Joshua D. Drake <jd(at)commandprompt(dot)com> wrote:
> Oliver Crosby wrote:
> > Hi,
> > I'm running Postgres 7.4.6 on a dedicated server with about 1.5gigs of ram.
> > Running scripts locally, it takes about 1.5x longer than mysql, and the
> > load on the server is only about 21%.
> 
> What queries?
> What is your structure?
> Have you tried explain analyze?
> How many rows in the table?
> Which OS?
> How are you testing the speed?
> What type of RAID?
> 
> 
> 
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