Re: Postgresql 8.1.4 - performance issues for select on

Hello,

It looks like some of you missed my first email but my
problem is not to find a replacement for this select:
select max(transid) from someunionview
Thare are plenty of solutions for doing this...

My point is to split a tale in two and to make this
transparent for the developers as a first step. On the
second step they will improve some of the queries but
that is another story.

So I would like to know if there is any plan to
improve this type of query for views in the near
future, or maybe it is alredy improved in 8.2 version?
I have the same problem and question for:
select transid from someunionview order by transid
desc limit 1;

Thank you for your time,
Ioana Danes

--- Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Jeff Davis <pgsql(at)j-davis(dot)com> writes:
> > If PostgreSQL could sort the result of a union by
> merging the results of
> > two index scans, I think the problem would be
> solved. Is there something
> > preventing this, or is it just something that
> needs to be added to the
> > planner?
>
> It's something on the wish-list. Personally I'd be
> inclined to try to
> rewrite the query as a plain MAX() across rewritten
> per-table indexed
> queries, rather than worry about mergesort or
> anything like that.
> There wasn't any very good way to incorporate that
> idea when planagg.c
> was first written, but now that the planner has an
> explicit notion of
> "append relations" it might be relatively
> straightforward.
>
> regards, tom lane
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 6: explain analyze is your friend
>

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