| From: | Markus Wanner <markus(at)bluegap(dot)ch> |
|---|---|
| To: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
| Cc: | Claudio Freire <klaussfreire(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Yuri Levinsky <yuril(at)celltick(dot)com>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Hash partitioning. |
| Date: | 2013-06-26 13:47:43 |
| Message-ID: | 51CAF0FF.9020406@bluegap.ch |
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| Lists: | pgsql-hackers |
On 06/25/2013 11:52 PM, Kevin Grittner wrote:
> At least until we have parallel
> query execution. At *that* point this all changes.
Can you elaborate on that, please? I currently have a hard time
imagining how partitions can help performance in that case, either. At
least compared to modern RAID and read-ahead capabilities.
After all, RAID can be thought of as hash partitioning with a very weird
hash function. Or maybe rather range partitioning on an internal key.
Put another way: ideally, the system should take care of optimally
distributing data across its physical storage itself. If you need to do
partitioning manually for performance reasons, that's actually a
deficiency of it, not a feature.
I certainly agree that manageability may be a perfectly valid reason to
partition your data. Maybe there even exist other good reasons. I don't
think performance optimization is one. (It's more like giving the system
a hint. And we all dislike hints, don't we? *ducks*)
Regards
Markus Wanner
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