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Bitmap indexes can substantially improve performance of queries with the following characteristics:
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Bitmap indexes are not ideal for online transaction processing (OLTP) environments because of their locking behavior. It is not possible to lock a single bitmap position. The smallest amount of a bitmap that can be locked is a bitmap segment, which can be up to half a data block in size. Changing the value of a row results in a bitmap segment becoming locked, in effect blocking changes on a number of rows. This is a serious disadvantage when
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