Re: Prepared statements performance

Doing the same tests from psql gives:

1. ~2.5 seconds for INSERT/VALUES
2. ~10 seconds for prepared statement executes
3. ~15 seconds for multiple INSERTs

Dan.

On Thu, May 10, 2012 at 3:42 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Alban Hertroys <haramrae(at)gmail(dot)com> writes:
> > On 10 May 2012 15:05, Radosław Smogura <rsmogura(at)softperience(dot)eu> wrote:
> >> May I ask what kind of planning may occur during insert?
>
> > Well, for example, if there's a unique constraint on the table then
> > the database will have to check that the newly inserted values don't
> > conflict with values that are already in the table. It needs to plan
> > an efficient strategy for that, which depends on the values being
> > inserted.
>
> There is no planning associated with checking unique constraints; that's
> just a matter for the index mechanisms.
>
> I think the real point here is that a simple INSERT/VALUES has such a
> trivial plan that there is hardly any gain to be had by avoiding the
> planning stage. Then the other overhead of a prepared statement
> (looking up the saved plan, checking it's not stale, etc) outweighs
> that. Or at least it could. 3x slower seems a bit fishy; I wonder
> whether there's some client-side inefficiency involved in that.
> Doing performance measurements with pgAdmin seems pretty questionable
> in the first place ...
>
> regards, tom lane
>