Agenda Introduction Bitmap Row Sources Internal Structures Bitmap Index DML Conclusion Bitmap Indexes Introduced in Oracle 7.3 Originally intended for columns with Low ...

Low data cardinality Bitmap indexes are extremely compact That is their primary advantage No real magic involved Less I/O is faster, plain and simple Still, no matter how ...

Mapping Bitmaps to Rowids Optimization Creation Of Bitmap indexes Creation Of Bitmap indexes (1st Salve Set) Creation Of Bitmap indexes Creation Of Bitmap indexes 2nd ...

... repeated 125,000 times Size ~ 1,000,000 bits or approx 140 Kbytes Full bitmap = 1.12 Mbytes But BTree index for such data would be around 12MB Conclusion Bitmap indexes ...

(Obs:Most DBMSs automatically index PK) Different Type of Indexes B-Trees (traditional) indexes Hash-cluster Bitmap indexes Index-Organized Tables Reverse-Key Indexes ...

More Advanced Indexing Topics Index-organised tables Bitmap indexes Clusters Index organised tables Index organised tables Entries of index are table records rather than ...

* Bitmap indexes Bitmap index Create 1 index for each value in domain of attribute Bitmap=1 for value, 0 for others E.g. (N, S, E, W requires 4 indexes) When would this be ...

... Indexes Indexes on heap organized tables can be B*Tree indexes Bitmap indexes B*Tree indexes contain Key (one or more table columns) Physical ROWID Bitmap indexes ...

... and Efficient Bitmap Indexes Histograms for Cost-Based Optimization “Star Transformation” explain plan Oracle 8.X lacks: List Partitioning Scalable Bitmap Indexes ...

Bitmap indexes are efficient for set-oriented operations. Materialized views Query results that have been stored in advance . * Partition and parallel execution Range ...

e.g. hash, range, multi-dimensional, bitmap indexes; Comparisons to other systems; Cassandra, Pnuts and MegaStore . Towards Elastic Transactional Cloud ...

Dimensional data model for fast query Star transformations using bitmap and bitmap-join indexes Partition pruning during queries Non-intrusive ETL processing Direct-path ...

Possible severe performance impact on bitmap indexes as new rows are added to table. Removal of errant table data usually involves use of conventional DELETE statements.

... compress and use order by candidate_column Table Compression Limitations Can not be used on LOB field Can not be used for IOTs Can not compress tables with bitmap indexes ...

Case 3: Available space = 100MB We can only materialize (cname) Q1 costs 100GB Q2 costs 100GB Q3 costs 30MB Average query cost = (200,030MB)/3 = 67GB Bitmap Indexes The ...

Bit Map Index Base Table Rating Index Region Index Customers where Region = W Rating = L And BitMap Indexes Comparison, join and aggregation operations are reduced to ...

... product category) Aggregates should be 5 to 10 times smaller Index Design One Very Simple Rule: All fact table, foreign key columns must have individual bitmap indexes ...

Rule 8: Stable columns with few values are good candidates for bitmap indexes if the columns appear in WHERE conditions. Rule 9: Avoid indexes on combinations of columns.

More precomputed aggregate tables (OLAP cubes) More indexes, materialized views ... loop join, flatfile reader persistence, cache, btrees, column read/write, bitmap indexes ...

... Aggregates should be 5 to 10 times smaller Time Aggregates Non-Time Aggregates Index Design All fact table, foreign key columns must have individual bitmap indexes on ...