Index - Bitmap

> Database > Oracle Database

1 - About

3 - BITMAP CONVERSION TO ROWIDS

[email protected]>SELECT * FROM emp WHERE job = 'CLERK' OR job = 'MANAGER';
 
Execution Plan
-----------------------------------------------------------------------------------------
| Id  | Operation                     | Name    | ROWS  | Bytes | Cost (%CPU)| TIME     |
-----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT              |         |     7 |   609 |     2   (0)| 00:00:01 |
|   1 |  INLIST ITERATOR              |         |       |       |            |          |
|   2 |   TABLE ACCESS BY INDEX ROWID | EMP     |     7 |   609 |     2   (0)| 00:00:01 |
|   3 |    BITMAP CONVERSION TO ROWIDS|         |       |       |            |          |  <-------- Here
|*  4 |     BITMAP INDEX SINGLE VALUE | JOB_IDX |       |       |            |          |
-----------------------------------------------------------------------------------------

We need for this query to get to the table. Here, Oracle will apply a function to turn the fact that i'th bit is on in a bitmap, into a rowid that can be used to access the table.

Advertising