SORT (GROUP BY NOSORT ROLLUP)

Description

Group rows together based on column values and perform a rollup. No sort is required

Versions

This operation was introduced in Oracle 9.0.1

This operation is implemented in the following versions

9.0.1
9.2.0
10.1.0
10.2.0

Example

Table must be indexed (to allow the NOSORT). Indexed column must be NOT NULL to allow use of the index

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) */ c1 FROM t1
    GROUP BY ROLLUP c1;

generates the following execution plan

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