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Bitmap Indexes → multiple rows. Bitmap indexes are primarily designed for data warehousing or environments in which queries … these rows. For this reason, bitmap indexes are not appropriate for many OLTP applications. See Also … : Oracle Database Performance Tuning Guide to learn how to use bitmap indexes
14.5 Using Bitmap Indexes for Performance → Bitmap indexes can substantially improve performance of queries that have all of the following … . The bitmap indexes used in the queries have been created on some or all of these low- or medium … -cardinality columns. The tables in the queries contain many rows. You can use multiple bitmap indexes
12.7 Viewing Bitmap Indexes with EXPLAIN PLAN → Index row sources using bitmap indexes appear in the EXPLAIN PLAN output with the word BITMAP … EXPLAIN PLAN with Bitmap Indexes EXPLAIN PLAN FOR SELECT * FROM t WHERE c1 = 2 AND c2 <> 6 OR c3 BETWEEN … 10 AND 20; SELECT STATEMENT TABLE ACCESS T BY INDEX ROWID BITMAP CONVERSION TO ROWID
Bitmap Indexes and Nulls → How to Determine Candidates for Using a Bitmap Index Bitmap indexes should help when either the … likely. Bitmap Indexes and Nulls Unlike most other types of indexes, bitmap indexes include rows that … joined with two or more dimension tables, and there
Bitmap Indexes on Partitioned Tables → You can create bitmap indexes on partitioned tables but they must be local to the partitioned table … —they cannot be global indexes. A partitioned table can only have global B-tree indexes, partitioned
Using Bitmap Join Indexes in Data Warehouses → index on the join column. Bitmap join indexes are much more efficient in storage than materialized … views do not compress the rowids of the fact tables. B-tree and bitmap indexes have different maximum … In addition to a bitmap index on a single table, you can create a bitmap join index,
Using Bitmap Indexes in Data Warehouses → Bitmap indexes are widely used in data warehousing environments. The environments typically have … data in the table. Bitmap indexes are typically only a fraction of the size of the indexed data in … bitmap index provides the same functionality as a regular index. Bitmap indexes
Enables the optimizer to cost a star transformation for star queries if true. The star transformation… → See Also: Oracle Database Reference for complete information about each initialization parameter
Table 3-2 Sample Bitmap → … Note: Bitmap indexes can include keys that consist entirely of values, unlike B-tree indexes … '); Bitmap indexes can process this query efficiently by counting the number of 1 values in the resulting … converts each bit in the bitmap to a rowid of the customers table. Each
About Indexes → Oracle Real Application Clusters applications Bitmap indexes: compact; work best for columns with a … Indexes are optional structures associated with tables and clusters that allow SQL queries to … . You can use indexes without rewriting any queries. Your results are the same, but you see them more … functionality.
Guidelines for Managing Indexes → Warehousing Guide for information about bitmap indexes Oracle Database Data Cartridge Developer's Guide for … This section discusses guidelines for managing indexes and contains the following topics: Create … Indexes After Inserting Table Data Index the Correct Tables and Columns Order Index Columns for … Performance
bitmap merge → DOB columns have bitmap indexes, then the database may use a bitmap merge if the query predicate is WHERE gender='F' AND DOB > 1966. … An operation that merges bitmaps retrieved from bitmap index scans. For example, if the gender and
Index the Correct Tables and Columns → regular indexes). There is a small range of values (good for bitmap indexes). The column contains … joins. Note: Primary and unique keys automatically have indexes, but you might want to create an index … on a foreign key. Small tables do not require indexes. If a query is taking too long, then the
Benefits for Data Warehousing Applications → Bitmap indexes are primarily intended for data warehousing applications where users query the data … transactions modifying the data. Parallel query and parallel DML work with bitmap indexes. Bitmap … , \"Schema Modeling Techniques\" for further information about using bitmap indexes
gender='M' gender='F' → ' AND cust_income_level IN ('H: 150,000 - 169,999', 'G: 130,000 - 149,999'); Bitmap indexes can … Query Using Bitmap Indexes Description of \"Figure 7-1 Executing a Query Using Bitmap Indexes\" … cust_id 130 1 0 cust_id 140 1 0 Each entry (or bit) in the bitmap corresponds
7 Indexes → This chapter contains the following topics: Using Bitmap Indexes in Data Warehouses Using B-Tree … Indexes in Data Warehouses Using Index Compression Choosing Between Local Indexes and Global Indexes
Using B-Tree Indexes in Data Warehouses → third normal form schemas. In general, bitmap indexes should be more common than B-tree indexes in … most data warehouse environments. B-tree and bitmap indexes have different maximum column limitations … Bitmap Join Index Restrictions and Requirements Join results must be stored, therefore,
Choosing Between Local Indexes and Global Indexes → indexes (for example, a unique index on a non-partitioning key, or a performance requirement). Bitmap indexes on partitioned tables are always local. … B-tree indexes on partitioned tables can be global or local. With Oracle8 i and earlier releases … , Oracle recommended that global indexes not be used
Using Index Compression → Bitmap indexes are always stored in a patented, compressed manner without the need of any user … intervention. B-tree indexes, however, can be stored specifically in a compressed manner to enable huge
Cardinality → The advantages of using bitmap indexes are greatest for columns in which the ratio of the number of … a bitmap index. However, data warehouse administrators also build bitmap indexes on columns with … unique). The majority of indexes in a data warehouse should be bitmap