Oracle-L: RE: Need help

From: Jankovic, Djordje <Djordje.Jankovic_at_attcanada.com>
Date: Mon, 02 Jun 2003 10:34:40 -0800
Message-ID: <F001.005A84ED.20030602103440@fatcity.com>

I have done some test before and found out that analyze is faster than dbms_stats for smaller tables only (less than 10M) - and the difference was not that big (for example very small tables dbms_stats would do a compute instead of estimate). For large tables they are pretty much the same. And this is comparing dbms_stats working in serial mode. You can do stuff in parallel which could change the picture in dbms_stats favor.

dbms_stats is more accurate (since its introduction incorrect statistics gathering was discovered for ANALYZE), it supports better granularity control (partitions, subpartitions). Using dbms_stats you can also export and import statistics: save the old statistics before the run and reuse the old statistics in case you don't like the new ones.

There are a number of other advantages: treating stale tables, automatic estimate sample size, collecting histogram info only for skewed columns (at least the ones that oracle thinks are skewed). Using dbms_stats you can also collect system stats.

And analyze is not depreciated in 9i.

AFAIK the only things dbms_stats does not do are: finding chained/migrated rows, computing cluster statistics, and validating the structure.

Djordje

-----Original Message-----
[mailto:JKmurthy_at_chn.cognizant.com]
Sent: Monday, June 02, 2003 10:50 AM
To: Multiple recipients of list ORACLE-L

Hi all,

Can anyone tell me which of the following performs better in collecting statistics of a table: Analyze command or
Dbms_stats.gather_table_stats

I tried my queries with both the options -- but always Analyze is out-performing the dbms_stats. But i read in a document that Dbms_stats performs better !! Besides I also read that Analyze command will be deprecated from Oracle 9i.

So can anyone tell me why dbms_stats is performing poor... Are there any paramters that need to be set to increase the performace of dbms_stats ?

Thanks in advance.

Regards
Kesh

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Author: Jankovic, Djordje
INET: Djordje.Jankovic_at_attcanada.com

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