From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Greg Stark <gsstark(at)mit(dot)edu>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: remove flatfiles.c |
Date: | 2009-09-02 02:55:14 |
Message-ID: | 603c8f070909011955t5046cbffx272584cb005fb12f@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, Sep 1, 2009 at 7:42 PM, Tom Lane<tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Greg Stark <gsstark(at)mit(dot)edu> writes:
>> On Wed, Sep 2, 2009 at 12:01 AM, Alvaro
>> Herrera<alvherre(at)commandprompt(dot)com> wrote:
>>>> The use cases where VACUUM FULL wins currently are where storing two
>>>> copies of the table and its indexes concurrently just isn't practical.
>>>
>>> Yeah, but then do you really need to use VACUUM FULL? If that's really
>>> a problem then there ain't that many dead tuples around.
>
>> That's what I want to believe. But picture if you have, say a
>> 1-terabyte table which is 50% dead tuples and you don't have a spare
>> 1-terabytes to rewrite the whole table.
>
> But trying to VACUUM FULL that table is going to be horridly painful
> too, and you'll still have bloated indexes afterwards. You might as
> well just live with the 50% waste, especially since if you did a
> full-table update once you'll probably do it again sometime.
>
> I'm having a hard time believing that VACUUM FULL really has any
> interesting use-case anymore.
What if your large table doesn't have an index? Then there's no way to cluster.
I'm a bit skeptical about partitioning as a solution, too. The
planner is just not clever enough with partitioned tables, yet.
...Robert
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