BITMAP COMPACTION

Description

Compresses a bitmap during bitmap index creation

Versions

This operation was introduced in Oracle 8.0.4

This operation is implemented in the following versions

Example

This operation can only be observed by using EXPLAIN PLAN to populate the plan table. It does not appear in AUTOTRACE or V$SQL_PLAN

This example was developed using Oracle 9.2.0.1 on Windows 2000

This example requires the following table and index definitions

    CREATE TABLE t1 (c1 NUMBER);

The table does not need to be analysed

The statement

    EXPLAIN PLAN FOR
    CREATE BITMAP INDEX i1 ON t1 (c1);

generates the following execution plan

0     CREATE INDEX STATEMENT Optimizer=CHOOSE
1   0   INDEX BUILD (NON UNIQUE) OF 'I1'
2   1     BITMAP COMPACTION
3   2       SORT (CREATE INDEX)
4   3         BITMAP CONSTRUCTION
5   4           TABLE ACCESS (FULL) OF 'T1'