SORT (GROUP BY STOPKEY)

Description

Group rows together based on column values. Number of rows returned is restricted using the ROWNUM pseudo-column.

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);

The table does not need to be analysed

The statement 

    SELECT * FROM 
    (
      SELECT c1 FROM t1
      GROUP BY c1
    )
    WHERE ROWNUM < 10;

generates the following execution plan 

0     SELECT STATEMENT Optimizer=CHOOSE
1   0   COUNT (STOPKEY)
2   1     VIEW
3   2       SORT (GROUP BY STOPKEY)
4   3         TABLE ACCESS (FULL) OF 'T1'