SORT (UNIQUE NOSORT)

Description

Removes duplicates from sorted list of rows

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 definition 

    CREATE TABLE t1 (c1 NUMBER NOT NULL);
	
	CREATE INDEX i1 ON t1 (c1);

The table does not need to be analysed

The statement 

    SELECT /*+ INDEX (t1 i1) */ DISTINCT c1 FROM t1;

generates the following execution plan 

0     SELECT STATEMENT Optimizer=CHOOSE
1   0   SORT (UNIQUE NOSORT)
2   1     INDEX (FULL SCAN) OF 'I1'