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.
>> Also perhaps tables where there are too many large indexes to make
>> rebuilding them all in one maintenance window practical.
>
> If that's the concern maybe we oughta do something about concurrently
> re-creating those indexes somehow. Plain REINDEX doesn't work of
> course, but maybe we can do some trick with creating a new index and
> dropping the original one afterwards.
Well that doesn't really work if you want to rewrite the table.
CLUSTER has to rebuild all the indexes when it's done.
I think the solution for both of these is actually partitioning. The
bottom line is that having a single table which contains very large
amounts of data is awkward to maintain.
--
greg
http://mit.edu/~gsstark/resume.pdf