Re: vacuum performance on insert

"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> Sean Chen <zyschen(at)gmail(dot)com> wrote:
>> 1, delete records ...
>> 2, insert records ...
>>
>> if I add "vacuum analyze" in-between this two steps, will it help
>> on the performance on the insert?

> Assuming there are no long-running transactions which would still be
> able to see the deleted rows, a VACUUM between those statements
> would allow the INSERT to re-use the space previously occupied by
> the deleted rows, rather than possibly needing to allocate new space
> from the OS.

But on the other side of the coin, the ANALYZE step is probably not very
helpful there. Better to do that after you've loaded the new data.

regards, tom lane