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Home -> Community -> Usenet -> c.d.o.misc -> Re: Analyze tables
Pascale Marois wrote:
>
> Thank you for the answer.
>
> I didn't analyze the sys or sytem objects but only those used by the
> application.
>
> Also, I read in a book of Oracle tuning that ALL tables must be analyzed.
> This is the reason I runned that script.
>
> I'm still reading......
>
> Van Messner wrote in message ...
> >You need to read about Rule and Cost based optimization. Then check to see
> >what the two databases are doing. Be sure NOT to analyze objects owned by
> >SYS or SYSTEM.
> >
> >Van
> >
> >Pascale Marois <pascalem_at_total.net> wrote in message
> >news:XybE3.415$HU1.60883_at_news.total.net...
> >> I'm very new a the role of DBA and I would like to submit this question:
> >>
> >> Two weeks ago, I runned a script to analyze all the tables on the
> >> development database. Everything was fine and then, last week, I runned
> >the
> >> same script on the production database. After this, many SELECT were
> >> extremely slow. I had to delete statistics on many tables and then
> >> everything was OK.
> >>
> >> I can't explain why it didn't work. The development database has
> >> approximately the same size then the production one.
> >>
> >> Does someone can explain it for me?
> >>
> >>
> >>
> >
> >
If none of the tables are analyzed, then the RULE optimiser is used - ie Oracle looks at the format of the SQL and determines the path to use. If there are stats (from the analyze) command, the Oralce use the COST optimiser which GENERALLY gives a better result...
You may need to look at which SQL's run badly and tune them
HTH
--
"Some days you're the pigeon, and some days you're the statue." Received on Fri Sep 17 1999 - 09:35:38 CDT
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