Re: Big IN() clauses etc : feature proposal

> You might consider just selecting your primary key or a set of
> primary keys to involved relations in your search query.  If you
> currently use "select *" this can make your result set very large.
>
> Copying all the result set to the temp. costs you additional IO
> that you propably dont need.

    It is a bit of a catch : I need this information, because the purpose of
the query is to retrieve these objects. I can first store the ids, then
retrieve the objects, but it's one more query.

> Also you might try:
>      SELECT * FROM somewhere JOIN result USING (id)
> Instead of:
>      SELECT * FROM somewhere WHERE id IN (SELECT id FROM result)

    Yes you're right in this case ; however the query to retrieve the owners
needs to eliminate duplicates, which IN() does.

> On the other hand if your search query runs in 10ms it seems to be fast
> enough for you to run it multiple times.  Theres propably no point in
> optimizing anything in such case.

    I don't think so :
    - 10 ms is a mean time, sometimes it can take much more time, sometimes
it's faster.
    - Repeating the query might yield different results if records were added
or deleted in the meantime.
    - Complex search queries have imprecise rowcount estimates ; hence the
joins that I would add to them will get suboptimal plans.

    Using a temp table is really the cleanest solution now ; but it's too
slow so I reverted to generating big IN() clauses in the application.