Re: First steps with 8.3 and autovacuum launcher

Matthew T. O'Connor escribió:
> Tom Lane wrote:
>> Alvaro Herrera <alvherre@commandprompt.com> writes:
>>   
>>> This is an interesting idea, but I think it's attacking the wrong
>>> problem.  To me, the problem here is that an ANALYZE should not block
>>> CREATE INDEX or certain forms of ALTER TABLE.
>>
>> I doubt that that will work; in particular I'm pretty dubious that you
>> can safely make CREATE INDEX and VACUUM run together.  Since they'd be
>> unlikely to be using the identical OldestXmin horizon, you'd likely end
>> up with dangling index entries (ie, CREATE INDEX indexes a tuple that
>> the VACUUM removes shortly afterward).
>
> I think the main issue is ANALYZE not VACUUM (at least in this thread) 
> since it's DB load times that are in question.

Right.  Autovac will not issue VACUUM against the freshly restored
tables anyway, since there are no deleted tuples.

> Can CREATE INDEX and ANALYZE be made to run concurrently?

I don't see why not (except for the fact that both try to update
reltuples and relpages AFAIR, so we would need to be careful about
that).

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.