Databases · Middle · Question 72 of 75
What is a 'Bitmap Heap Scan' in an EXPLAIN plan?
- ✓Correct answer: PostgreSQL first collects matching row locations from one or more indexes into a bitmap, then reads table pages in physical order
- 2A scan of image columns
- 3A full table scan with compression
Explanation
It sits between an index scan and a seq scan: good for medium selectivity, and it can combine several indexes with AND/OR.