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Re: is "db/revs" always going to be one flat directory (FSFS)?

From: <kfogel_at_collab.net>
Date: 2004-11-29 20:19:37 CET

Subversion Newbie <subversionnewbie@yahoo.com> writes:
> Just wondering if there are plans to have the "db/revs"
> directory under the repository use a multi-level ("hashed")
> scheme, similar to what postfix does with its "hash_queue_depth"
> option.
> Those of us using Linux with EXT2 or EXT3 filesystems (and
> probably Solaris people, too) will probably see a performance
> hit when we start reaching a few thousand revisions (i.e., files
> in db/revs) given that the lookup for a directory entry is
> pretty much sequential. Just curious.

This is one of those FAQs that seems to come up a lot with the FSFS
repository storage scheme.

Greg Hudson (I believe) tested at least EXT3 up to hundreds of
thousands of revisions, and saw no performance decrease.

Now, possibly that test was skewed, because the inodes would have
ended up right near each other, because the test was being run all at
once -- whereas in real life there would be many other disk events in
between Subversion revisions. Nevertheless, Greg's results are all we
have to go on right now. We have heard speculation that there might
be a performance problem someday, but we've never had a report of an
actual problem.

-Karl

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Received on Mon Nov 29 20:28:39 2004

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