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Re: Calling conventions

From: Matthew Wakeling <matthew(at)flymine(dot)org>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Calling conventions
Date: 2009-07-21 13:50:01
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Mon, 20 Jul 2009, Kevin Grittner wrote:
> Oh, well, if you load all the data into Java's heap and are accessing
> it through HashMap or similar, I guess a factor of 100 is about right.

No, that's not what I'm doing. Like I said, I have implemented the very 
same algorithm as in Postgres, emulating index pages and all. A HashMap 
would be unable to answer the query I am executing, but if it could it 
would obviously be very much faster.

> I see the big difference as the fact that the Java implementation is
> dealing with everything already set up in RAM, versus needing to deal
> with a "disk image" format, even if it is cached.

The java program uses as near an on-disc format as Postgres does - just 
held in memory instead of in OS cache.


 Okay, I'm weird! But I'm saving up to be eccentric.

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