Message-ID: <45C87FAD.2010207@archonet.com>
Date: Tue, 06 Feb 2007 13:16:29 +0000
From: Richard Huxton <dev@archonet.com>
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To: "Hiltibidal, Robert" <Robert.Hiltibidal@argushealth.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Index ANDing & Index ORing
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Hiltibidal, Robert wrote:
> Morning
> 
> I currently use DB2 on an AIX 5.2 p5 platform 7gb ram for log analytics
> with heavy OLAP querying.
> 
> Index ANDing in DB2 allows for multiple indexes to be used in joins. I'm
> not sure of the ORing function yet.

That's what 8.1+ support. The bitmap is in-memory though.

> DB2 does not really allow for WAL to be turned off. Consequently the max
> throughput on queries I have been able to achieve is 367 inserts a
> second. This is on shark disk not local. That number was achieved with 3
> log imports running at once.

Hmm - with battery-backed write-cache on the disks I'd expect better 
than that. Let's see - 367 inserts/sec * 60 =~ 22000 / 3 =~ 7000 inserts 
/min (assuming 1 log). You should be able to do better than that with 
decent disks.

> I'm looking for a solution that allows me to turn WAL on or off
> depending on need. 

I'm not sure what the connection is, but PostgreSQL doesn't allow WAL to 
be turned off. You can turn off fsync, but you can only change this when 
you restart postgresql.

-- 
   Richard Huxton
   Archonet Ltd