PARTITION HASH (EMPTY)

Description

Does not execute the child operations for any partition

Versions

This operation was introduced in Oracle 8.1.5

This operation is implemented in the following versions

8.1.5
8.1.6
8.1.7
9.0.1
9.2.0

This operation has not yet been observed in Oracle 10.2

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,c2 NUMBER)
    PARTITION BY HASH (c1)
    PARTITIONS 4;

The table does not need to be analysed

The statement

    SELECT c1 FROM t1
    WHERE c1 = NULL;

generates the following execution plan

0     SELECT STATEMENT Optimizer=CHOOSE
1   0   PARTITION HASH (EMPTY)
2   1     TABLE ACCESS (FULL) OF 'T1'

Note that the predicate c1 = NULL is syntactically valid, but semantically meaningless