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Re: PostgreSQL as a local in-memory cache

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: PostgreSQL as a local in-memory cache
Date: 2010-06-16 19:00:22
Message-ID: 4C191F46.4060408@agliodbs.com (view raw or flat)
Thread:
Lists: pgsql-performance
> * fsync=off => 5,100
> * fsync=off and synchronous_commit=off => 5,500

Now, this *is* interesting ... why should synch_commit make a difference
if fsync is off?

Anyone have any ideas?

> tmpfs, WAL on same tmpfs:
> * Default config: 5,200
> * full_page_writes=off => 5,200
> * fsync=off => 5,250
> * synchronous_commit=off => 5,200
> * fsync=off and synchronous_commit=off => 5,450
> * fsync=off and full_page_writes=off => 5,250
> * fsync=off, synchronous_commit=off and full_page_writes=off => 5,500

So, in this test, it seems like having WAL on tmpfs doesn't make a
significant difference for everything == off.

I'll try running some tests on Amazon when I have a chance.  It would be
worthwhile to get figures without Python's "ceiling".

-- 
                                  -- Josh Berkus
                                     PostgreSQL Experts Inc.
                                     http://www.pgexperts.com

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Subject: Re: PostgreSQL as a local in-memory cache
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