BITMAP CONVERSION (FROM ROWIDS)

Description

Converts a set of ROWIDS into a set of bitmap

Versions

This operation is implemented in the following versions

7.3.4
8.0.4
8.0.5
8.0.6
8.1.5
8.1.6
8.1.7
9.0.1
9.2.0
10.1.0
10.2.0

Example

This example was developed using Oracle 9.2.0.1 on Windows 2000

This example requires the following table and index definitions 

    CREATE TABLE t1 (c1 NUMBER,c2 NUMBER);

    CREATE BITMAP INDEX i1 ON t1 (c1);
    CREATE INDEX i2 ON i1 (c2);

The table does not need to be analyzed

The statement 

    SELECT /*+ INDEX_COMBINE (t1 i1 i2) */ c1 
    FROM t1
    WHERE c1 = 0 AND c2 = 0;

generates the following execution plan 

0     SELECT STATEMENT Optimizer=CHOOSE
1   0   BITMAP CONVERSION (TO ROWIDS)
2   1     BITMAP AND
3   2       BITMAP INDEX (SINGLE VALUE) OF 'I1' 
4   2       BITMAP CONVERSION (FROM ROWIDS)
5   4         INDEX (RANGE SCAN) OF 'I2' (NON-UNIQUE)