Re: join over 12 tables takes 3 secs to plan

On Thu, 2003-01-02 at 15:40, Joe Conway wrote:
> Hilmar Lapp wrote:
> > As an added note, appreciating that query optimization is a difficult
> > problem, and I do think PostgreSQL is a great product. Having said
> > that, I've written 16-table joins for Oracle and always found them to
> > plan within a second or two, so that's why I thought there's nothing
> > special about the query I posted ... I'm not saying this to be bashful
> > about PostgreSQL, but rather to suggest that apparently there are ways
> > to do it pretty fast.
>
> I could be wrong, but I believe Oracle uses its rule based optimizer by
> default, not its cost based optimizer. A rule based optimizer will be very
> quick all the time, but might not pick the best plan all the time, because it
> doesn't consider the statistics of the data. Any idea which one you were using
> in your Oracle experience?

Remember also that the commercial RDMBSs have had many engineers working
for many years on these problems, whereas PostgreSQL hasn't...

Could it be that PG isn't the proper tool for the job? Of course,
at USD20K/cp, Oracle may be slightly out of budget.

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