On Tue, Sep 1, 2009 at 7:42 PM, Tom Lane<tgl@sss.pgh.pa.us> wrote:
> Greg Stark <gsstark@mit.edu> writes:
>> On Wed, Sep 2, 2009 at 12:01 AM, Alvaro
>> Herrera<alvherre@commandprompt.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
