Re: dbms_stats and incorrect statistics
- From: Wolfgang Breitling <breitliw@xxxxxxxxxxxxx>
- To: ronnie_doggart@xxxxxxxxx
- Date: Thu, 31 May 2007 08:13:02 -0600
I bet DATEFIRED has 5842 NULLs - or had at the time you gathered the stats.
At 01:12 AM 5/31/2007, Ronnie Doggart wrote:
Hi,
Oracle 9.2.0.8 on Oracle Enterprise Linux
We looking at reducing the amount of time taken to gather statistics
on our production database. Initially we where using
dbms_stats.gather_schema_stats with compute and cascade=>true. We
want to use an estimate on the tables and compute on the indexes so
we split the analysis up. However during testing we noticed that
some tables had stats that where inconsistent. For instance using
dbms_stats.gather_table_stats with compute the number of rows
reported as sampled varied on a column per column basis in the same table e.g
TABLE_NAME COLUMN_NAME
DATA_TYPE NUM_DISTINCT SAMPLE_SIZE
LGNCC_ESCRULE ESCRULESTATUS NUMBER
4 14563
LGNCC_ESCRULE DATEFIRED
DATE 4896 8721
Does a compute not read all the rows in a table for each column, the
table above has 14563 rows.
Regards
Wolfgang Breitling
Centrex Consulting Corporation
www.centrexcc.com
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