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Current maintainer:Bruce Momjian (pgman@candle.pha.pa.us)

Last updated:Wed Nov 317:20:38 EST 2004

Last updated:Wed Nov 322:57:53 EST 2004

The most recent version of this document can be viewed at the PostgreSQL web

site, http://www.PostgreSQL.org.

* Allow the creation of bitmap indexes which can be quickly combined

with other bitmap indexes

Bitmap indexes index single columnsand can be combined with other bitmap

Bitmap indexes index single columnsthat can be combined with other bitmap

indexes to dynamically create a composite index to match a specific query.

Each index is a bitmap, and the bitmaps are bitwise AND'ed or OR'ed to be

combined.

combined. Such indexes could be more compact if there are few unique

value. Also, perhaps they can be lossy requiring a scan of the heap page

to find matching rows.

* Allow non-bitmap indexes to be combined

Do loUse bitmaps to combine non-bitmap indexes

Do lookups on non-bitmap indexes and create bitmaps in memory that can be

combined with other indexes.

* Allow use of indexes to search for NULLs

One solution is to create a partial index on an IS NULL expression.