Skip site navigation (1) Skip section navigation (2)

Re: How to force Nested Loop plan?

From: Rob Nagler <nagler(at)bivio(dot)biz>
To: PgSQL Performance ML <pgsql-performance(at)postgresql(dot)org>
Subject: Re: How to force Nested Loop plan?
Date: 2003-08-30 23:59:33
Message-ID: 16209.14949.507000.384083@gargle.gargle.HOWL (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
Ron Johnson writes:
> Dumb question: given your out-of-the-box satisfaction, could it be
> that postgresql.conf hasn't been tweaked?

Here are the modified values:

shared_buffers = 8000
wal_buffers = 80
sort_mem = 32000
effective_cache_size = 400000
random_page_cost = 4
autocommit = false
timezone = UTC

I had run a test with effective_cache_size to high value to see what
would happen.  Also adjusted random_page_cost:

random_page_cost effective_cache_size	elbow
    4	    	    	40000	    	675
    .5	    	    	40000	    	592
    .1	    	    	40000	    	392
    4	    	    	1000	    	30

My conclusion is that random_page_cost should be left alone and
effective_cache_size higher is better.

BTW, the hardware is 2 x 2.4ghz Xeon, 1.2GB, SCSI (linux software
raid) with 10K disks.  This is close to the production box.  Although
we are planning on adding more memory to production.


In response to

pgsql-performance by date

Next:From: Rob NaglerDate: 2003-08-31 00:08:32
Subject: Re: How to force Nested Loop plan?
Previous:From: Tom LaneDate: 2003-08-30 22:10:41
Subject: Re: How to force Nested Loop plan?

Privacy Policy | About PostgreSQL
Copyright © 1996-2017 The PostgreSQL Global Development Group