How to create bitmap index in PostgreSQL? (Does it even have bitmap index ?)

Question

I have been "googling" at least for an hour, but I was unable to find how to create a bitmap index in PostgreSQL, so my question is very simple: how to write this command (from Oracle) in PostgreSQL:

CREATE BITMAP INDEX name  ON table (column);

no, Postgres does not have it, but if you have very few possible values (and especially if they are very asymmetrically dispersed) consider trying PARTIAL INDEX — Vao Tsun
– Vao Tsun, Commented Aug 20, 2015 at 7:53
You can put for what purpose you want to create bitmat, refer this documentation which says bit map is created automatically by postgre (in memory) but not by any user. — MarmiK
– MarmiK, Commented Aug 20, 2015 at 8:17
to mef: I did, no answer found ... to Marmik: I was looking into explain plan for my query which was ideal for using of bitmap indexes but non was automatically created and sequence scan was used instead — Baker
– Baker, Commented Aug 20, 2015 at 8:31
If you have a slow query please read this: stackoverflow.com/tags/postgresql-performance/info and then post the relevant information. — user330315
– user330315, Commented Aug 20, 2015 at 9:04

Correcter · Accepted Answer · 2017-09-24 17:16:26Z

3

The bitmap of pages is created dynamically for each query. It is not cached or re-used, and is discarded at the end of the bitmap index scan.

It doesn't make sense to create the page bitmap in advance because its contents depend on the query predicates.

Bitmap index create a separate bitmap (a sequence of 0 and 1) for each possible value of the column, where each bit corresponds to a string with an indexed value. Bitmap indexes are optimal for data where bit unique values (example, gender field)

PostgreSQL does not provide persistent bitmap index. But it can be used in database to combine multiple indexes. PostgreSQL scans each needed index and prepares a bitmap in memory giving the locations of table rows that are reported as matching that index’s conditions. The bitmaps are then ANDed and ORed together as needed by the query. Finally, the actual table rows are visited and returned.

edited Sep 24, 2017 at 17:16

user330315

answered Sep 24, 2017 at 16:31

Correcter

3,7162 gold badges18 silver badges14 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Dilan Sachintha Nayanajith · Accepted Answer · 2021-02-25 18:25:27Z

3

If you need, you can integrate roaring bitmaps into PostgreSQL. Roaring bitmaps are compressed bitmaps that tend to outperform conventional compressed bitmaps such as WAH, EWAH, or Concise.

You can use this repo to integrate roaring bitmaps. It contains an improved fork of Roaring bitmap implementation in greenplum-db.

answered Feb 25, 2021 at 18:25

Dilan Sachintha Nayanajith

7888 silver badges21 bronze badges

Collectives™ on Stack Overflow

How to create bitmap index in PostgreSQL? (Does it even have bitmap index ?)

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related