Bitmap index
From Oracle FAQ
⧼orafaq-jumptonavigation⧽⧼orafaq-jumptosearch⧽
A bitmap index is a type of index that uses a string of bits to quickly locate rows in a table. Bitmap indexes are normally used to index low cardinality columns in a warehouse environment.
History[edit]
Bitmap indexes was introduced in Oracle version 7.3.4.
Examples[edit]
Bitmap Index:
CREATE BITMAP INDEX emp_bitmap_idx ON big_emp(sex);
Bitmap Join Index:
CREATE BITMAP INDEX emp_dept_loc ON emp(dept.loc) FROM emp, dept WHERE emp.deptno = dept.deptno TABLESPACE index_ts1;
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