WINDOW (BUFFER PUSHED RANK)

Description

Analytic function

Versions

This operation was introduced in Oracle 8.1.6

This operation has not yet been observed in Oracle 9.2.0

This operation has been observed in the following versions

8.1.6
8.1.7
9.0.1

This operation has not yet been observed in Oracle 9.2 or 10.2

Example

In this example the table must have an index on the column(s) in the ORDER BY clause. The indexed column must be NOT NULL.

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,c2 NUMBER);

    CREATE INDEX i1 ON t1 (c1);

The table must be analysed 

    ANALYZE TABLE t1 COMPUTE STATISTICS;

The statement 

    SELECT c2,r1 FROM
    (
      SELECT c2,RANK () OVER
      (
        ORDER BY c1
      ) AS r1
      FROM t1
    ) 
    WHERE r1 < 10;

generates the following execution plan 

0     SELECT STATEMENT Optimizer=CHOOSE
1   0   VIEW
2   1     WINDOW (BUFFER PUSHED RANK)
3   2       TABLE ACCESS (BY INDEX ROWID) OF 'T1'
4   3         INDEX (FULL SCAN) OF 'I1' (NON-UNIQUE)