Re: [HACKERS] Big IN() clauses etc : feature proposal

PFC <lists(at)peufeu(dot)com> writes:

>
> I really like this. It's clean, efficient, and easy to use.
>
> This would be a lot faster than using temp tables.
> Creating cursors is very fast so we can create two, and avoid doing
> twice the same work (ie. hashing the ids from the results to grab categories
> only once).

Creating cursors for a simple plan like a single sequential scan is fast
because it's using the original data from the table. But your example was
predicated on this part of the job being a complex query. If it's a complex
query involving joins and groupings, etc, then it will have to be materialized
and there's no (good) reason for that to be any faster than a temporary table
which is effectively the same thing.

--
greg