Does PREPARE turn
select * from mytable
into
select mytable.field1,mytable.field2 from mynamespace.mytable
?
I was looking for this functionality for one of my projects so I'm curious.
On Monday 28 October 2002 06:55 pm, (Via wrote:
> That is a good question. The planner does more than just analyse the
> query. It generates the Plan used by the executor, so that can't be
> removed.
>
> It is always a pain when the optimizer/planner takes longer than the
> executor. We do have PREPARE/EXECUTE in 7.3beta for you to use.
>
>
> ---------------------------------------------------------------------------
>
> Ben McMahan wrote:
> > I'm looking at different ways of optimizing queries with a large number
> > of joins. I write the same query in a number of different ways and
> > compare the running times. Now the problem is I do not want the
> > optimizer changing the queries. So I explicit state the order of the
> > joins in the FROM clause. I also turn off everything I can except for
> > one type of join (say hash join), and I've turned off geqo. But I find
> > that the PLANNER still takes an enormous amount of time for some queries.
> > It doesn't look like the Planner is actually optimizing (changing)
> > anything, but just in case, I was wondering if there was a way to turn
> > off the PLANNER.
> >
> > Note, when I say an enormous amount of time, I mean at least double the
> > time the EXECUTOR takes to actually answer the query.
> >
> > Thanks for your help,
> >
> > Ben McMahan
> >
> > ps. here is a small example of what my queries look like (so you can see
> > if there is something else it might be deciding on):
> >
> > SELECT DISTINCT c0.x1 , c1.x2 , c0.x3 , c0.x4 , c2.x5
> > FROM r1 c4 (x4,x2,x5) JOIN (r0 c3 (x2,x3,x5) JOIN (r2 c2 (x3,x1,x5) JOIN
> > (r1 c1 (x4,x1,x2) JOIN r1 c0 (x1,x3,x4)
> > ON ( c0.x4 = c1.x4 AND c0.x1 = c1.x1 ))
> > ON ( c0.x3 = c2.x3 AND c0.x1 = c2.x1 ))
> > ON ( c1.x2 = c3.x2 AND c0.x3 = c3.x3 AND c2.x5 = c3.x5 ))
> > ON ( c0.x4 = c4.x4 AND c1.x2 = c4.x2 AND c2.x5 = c4.x5 );
> >
> > A quick reminder, FROM r1 c4 (x4,x2,x5) just renames a table r1 into c4
> > where it also renames the columns to x4, x2, and x5 respectively.
> >
> >
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