| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | postgres performance list <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: 8K recordsize bad on ZFS? |
| Date: | 2010-05-12 01:01:48 |
| Message-ID: | 4BE9FDFC.40401@agliodbs.com |
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| Lists: | pgsql-performance |
> Sure, but bulk load + reandom selects is going to *guarentee*
> fragmentatioon on a COW system (like ZFS, BTRFS, etc) as the selects
> start to write out all the hint-bit-dirtied blocks in random orders...
>
> i.e. it doesn't take long to make an originally nicely continuous block
> random....
I'm testing with DD and Bonnie++, though, which create their own files.
For that matter, running an ETL procedure with a newly created database
on both recordsizes was notably (2.5x) faster on the 128K system.
So I don't think fragmentation is the difference.
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com
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