From: | Dimitri Fontaine <dimitri(at)2ndQuadrant(dot)fr> |
---|---|
To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
Cc: | Dimitri Fontaine <dimitri(at)2ndQuadrant(dot)fr>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Jaime Casanova <jaime(at)2ndquadrant(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Itagaki Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org, Marko Tiikkaja <marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi>, Itagaki Takahiro <itagaki(dot)takahiro(at)gmail(dot)com> |
Subject: | Re: Syntax for partitioning |
Date: | 2011-11-15 10:40:30 |
Message-ID: | 87fwhp8y8x.fsf@hi-media-techno.com |
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Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> That said, I still don't see how you can enforce a unique index over
> multiple segments over something other than the partition key while
> still allowing quick dropping of segments. If you can fix that you can
> make it work for the current inheritence-style partitioning.
Well the Primary Key and the Physical Map Index do not need to be on the
same set of columns.
>> If you happen to drop a part of the data that fits in one or more
>> segments (and with a decent fillfactor you need less than 1GB to get
>> there), then you can unlink() whole files at a time. That would be the
>> goal here.
>
> I feel uncomfortable with the "happen to". You can add the magic too,
> but for scripting purposes I'd feel better if it could be done via DDL
> also. That way typos don't end up being 5 day queries all of a sudden.
If the data fills less than a segment then you can't unlink() the file,
you have to mark the tuples / pages as free space. If you have a
partial index matching the whole portion of data you're removing, you
can still drop it before hand — or maybe the system can be instructed to
do so?
Regards,
--
Dimitri Fontaine
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support
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