Re: Does table monitoring handle all statistics for you?

Then what statistics does DBMS_STATS gather that MONITORING does not? I think that is what I do not understand

Brian

On Mon, 25 Jun 2001 22:58:18 +0100, "Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote:

>
>Sorry - there are too many words with
>context-specific meanings in my reply.
>
>
>Assume you have a table with 1,000,000
>rows in it, which has been analyzed to
>generate statistics.
>
>Over the next 48 hours, you delete 10,000
>rows, and insert 65,000 rows. These are
>counted into mon_mod$ (or whatever it
>is called).
>
>Another table has 100,000 rows, but
>in the same time period you insert 100,
>and update 10.
>
>Eventually you call a procedure in the
>dbms_stats package to analyze
>'stale' tables. The code checks each table
>listed in mon_mod$ - finds one with 75,000
>changes compared to a base of 1,000,000
>rows - this is a relatively large change,
>so the table is re-analyzed; the next table
>is found to have 110 changes against a
>base of 100,000, a relatively small change,
>not enough to affect the stats appreciably
>so it is not reanalyzed.
>
>The figures for the larger table are deleted
>from mon_mod$, the figures for the smaller
>table are not.
>
>
>Possibly 'stale' is not the term used in
>the package, but I hope this clarifies what
>I meant by using the word.
>
>
>--
>Jonathan Lewis
>
>Host to The Co-operative Oracle Users' FAQ
>http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>
>Author of:
>Practical Oracle 8i: Building Efficient Databases
>See http://www.jlcomp.demon.co.uk/book_rev.html
>
>Seminars on getting the best out of Oracle
>See http://www.jlcomp.demon.co.uk/seminar.html
>
>
>
>
>
>
>Brian Tkatch wrote in message <3b379ca3.255933921_at_news.alt.net>...
>>On Mon, 25 Jun 2001 20:16:50 +0100, "Jonathan Lewis"
>><jonathan_at_jlcomp.demon.co.uk> wrote:
>>
>>>
>>>Monitoring keeps an approximate count
>>>of inserts, updates and deletes. Every
>>>three hours, SMON write the in-memory
>>>counts to a table (with a name like mon_mod$)
>>>
>>>You still need to sort out statistics from time
>>>to time,
>>
>>Why is that? What will fall out of order?
>>
>>> but the dbms_stats analyze procedures
>>>now have the option to 'analyze only stale objects';
>>
>>Which makes it run a lot faster. That is nice.
>>
>>
>>>Oracle then uses the values in mon_mod$ to
>>>decide if the existing stats qualify as stale.
>>>
>>
>>If is stale, then it hasn't been written. If it hasn't been written,
>>then there was nothing to update. If there was nothing to update who
>>cares if it is stale? Am I missing something?
>>
>>Brian
>
>
Received on Tue Jun 26 2001 - 08:58:03 CDT