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Re: Subversion's use of Berkeley DB [#11511]

From: Justin Erenkrantz <justin_at_erenkrantz.com>
Date: 2004-12-08 19:01:07 CET

--On Wednesday, December 8, 2004 12:38 PM -0500 Keith Bostic
<bostic@abyssinian.sleepycat.com> wrote:

> 1. The Subversion code is not setting the Berkeley DB cache size.
> Given Berkeley DB's small default cache size (256KB), and the
> expected good locality of reference for Subversion queries,
> I think Subversion will be able to increase performance by
> setting the cache size.
> You can set the cache in the DB_CONFIG file, or by using
> the DbEnv::set_cachesize method:
> http://www.sleepycat.com/docs/api_c/env_set_cachesize.html
> For more information, see the "Selecting a cache size"
> section of the Berkeley DB Reference Guide, included in your
> download package and also available at:
> http://www.sleepycat.com/docs/ref/am_conf/cachesize.html
> Action Items:
> Investigate the efficiency of the current Subversion cache
> (using the Berkeley DB db_stat utility), and see if there's
> benefit to be had by increasing the cache size.
> Change Subversion to specify a cache size whenever creating
> a Berkeley DB database environment.

The question I have is what's an appropriate cache size? 1M? 2M? 8M? 128M?

Can we change the cache size by just tweaking DB_CONFIG and restarting the
processes? Or, do we need to rebuild the database? (The docs I can find
aren't very helpful on this.)

If it helps, here's the db_stat -m output from our (svn.apache.org) install
using BDB 4.2:


This is a fairly loaded public SVN install... -- justin

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Received on Wed Dec 8 19:02:18 2004

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