Question on how cardinality is calculated.
Date: Thu, 10 Jan 2008 15:06:05 -0000
Does anyone know how Oracle calculates the cardinality of a query such as:
Select * from table_1 where upper(case) like '%12345%';
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=131 Card=5553 Bytes=621936)
1 0 TABLE ACCESS (FULL) OF 'TABLE_1' (Cost=131 Card=5553 Bytes=621936)
Oracle calculates that it is expecting 5553 rows from this query but I know it will only return 2.
How does it do its estimate ?
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http://www.freelists.org/webpage/oracle-l Received on Thu Jan 10 2008 - 09:06:05 CST