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- Bitmap_index abstract "A bitmap index is a special kind of database index that uses bitmaps.Bitmap indexes have traditionally been considered to work well for low-cardinality columns, which have a modest number of distinct values, either absolutely, or relative to the number of records that contain the data. The extreme case of low cardinality is Boolean data (e.g.,Does a resident in a city have internet access?), which has two values, True and False. Bitmap indexes use bit arrays (commonly called bitmaps) and answer queries by performing bitwise logical operations on these bitmaps. Bitmap indexes have a significant space and performance advantage over other structures for query of such data. Their drawback is they are less efficient than the traditional B-tree indexes for columns whose data is frequently updated: consequently, they are more often employed in read-only systems that are specialized for fast query - e.g., data warehouses, and generally unsuitable for online transaction processing applications. However, this drawback appears to apply only to their implementation in relational database management systems: certain non-relational DBMSs, notably Intersystems Cache, a hierarchical database, use bitmap indexes for low-cardinality columns in transactional systems.Some researchers argue that Bitmap indexes are also useful for moderate or even high-cardinality data (e.g., unique-valued data) which is accessed in a read-only manner, and queries access multiple bitmap-indexed columns using the AND, OR or XOR operators extensively.Bitmap indexes are also useful in data warehousing applications for joining a large fact table to smaller dimension tables such as those arranged in a star schema.".
- Bitmap_index wikiPageID "2017214".
- Bitmap_index wikiPageRevisionID "598767975".
- Bitmap_index hasPhotoCollection Bitmap_index.
- Bitmap_index subject Category:Bit_data_structures.
- Bitmap_index subject Category:Data_management.
- Bitmap_index subject Category:Database_index_techniques.
- Bitmap_index type Ability105616246.
- Bitmap_index type Abstraction100002137.
- Bitmap_index type Arrangement105726596.
- Bitmap_index type BitDataStructures.
- Bitmap_index type Cognition100023271.
- Bitmap_index type DataStructure105728493.
- Bitmap_index type DatabaseIndexTechniques.
- Bitmap_index type Know-how105616786.
- Bitmap_index type Method105660268.
- Bitmap_index type PsychologicalFeature100023100.
- Bitmap_index type Structure105726345.
- Bitmap_index type Technique105665146.
- Bitmap_index comment "A bitmap index is a special kind of database index that uses bitmaps.Bitmap indexes have traditionally been considered to work well for low-cardinality columns, which have a modest number of distinct values, either absolutely, or relative to the number of records that contain the data. The extreme case of low cardinality is Boolean data (e.g.,Does a resident in a city have internet access?), which has two values, True and False.".
- Bitmap_index label "Bitmap index".
- Bitmap_index label "Bitmap-Index".
- Bitmap_index sameAs Bitmapové_indexování.
- Bitmap_index sameAs Bitmap-Index.
- Bitmap_index sameAs m.06fcr7.
- Bitmap_index sameAs Q878825.
- Bitmap_index sameAs Q878825.
- Bitmap_index sameAs Bitmap_index.
- Bitmap_index wasDerivedFrom Bitmap_index?oldid=598767975.
- Bitmap_index isPrimaryTopicOf Bitmap_index.