Perform a descending index skip scan
This operation was introduced in Oracle 9.0.1
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 definition
CREATE TABLE t1 (c1 NUMBER,c2 NUMBER); CREATE INDEX i1 ON t1 (c1,c2);
Unlike INDEX (SKIP SCAN), the table must be analysed
ANALYZE TABLE t1 COMPUTE STATISTICS;
The statement
SELECT /*+ INDEX_SS_DESC (t1 i1) */ c1 FROM t1 WHERE c2 = 0;
generates the following execution plan
0 SELECT STATEMENT Optimizer=CHOOSE 1 0 INDEX (SKIP SCAN DESCENDING) OF 'I1' (NON-UNIQUE)