Converts a set of ROWIDS into a set of bitmap
This operation is implemented in the following versions
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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)