PostgreSQL High Performance Cookbook

Running bitmap heap and index scan

In this recipe, we will be discussing bitmap heap scans and index scans.

Getting ready

PostgreSQL does not support creating bitmap indexes on tables. However, it will generate bitmap pages while scanning the index, which will be utilized during the table scan. PostgreSQL does not generate bitmap pages for every index scan, and it will only generate them if the number of fetching rows from the query is high enough. This bitmap page is unique to each query execution, and the scope of the bitmap page is the end of the query execution.

Bitmap heap scans will always be the parent node type to the bitmap index scan, which takes the bitmap pages as an input, and sorts the index pages as the physical table page order, and ...