Re: Cost-based optimizer parser

Here's a thought -- perhaps your shared pool cache hit ratio is way low? B/ESTAT should either confirm or disconfirm this guess. If your sql trace shows high parse time, it may be that your application(s) issues so many different SQLs so that executed SQLs kept getting flushed out of SGA...

Pei
your friendly-neighbor DBA...

Michel Tilman <mctilman_at_cargo.be> wrote in article <6ji4du$p2a2_at_afrodite.telenet-ops.be>...
> Hello,
>
> Several months ago I posted a message indicating we had some problemes
with
> regards to the Oracle 7.3.3 optimizer, NOT with regards to the execution
> plan but related to very high parse times (e.g. 3 min parse vs 4sec
> execution). I could not follow up that message because of time
constraints.
> In the meantime, we encountered the same problem with some other queries,
> usually, when the number of tables in the select clause grows larger
(e.g.
> >= 5 tables).
> So far we have been unable to find any documentation on the parse
algorithm
> (to see if we could apply some sensible heuristics, as some of our
queries
> may be generated dynamically), neither was our local Oracle distributor
able
> to provide us with advanced information about the problem. Is it related
to
> older (say pre-8) versions, is it intrinsic to cost-based optimization
(i.e.
> a finding an optimum plan vs a good one), ... . Anyone having any ideas
or
> some good pointers to information on this topic?
>
> Thanks,
>
> Michel Tilman
>
> =====
>
> Remove the c's from my mail address
>
>
>
>
Received on Mon May 18 1998 - 22:02:47 CDT