Skip site navigation (1) Skip section navigation (2)

Peripheral Links

Header And Logo

PostgreSQL
| The world's most advanced open source database.

Site Navigation

Search for
  Advanced Search

Re: Group by more efficient than distinct?



On Freitag, 18. April 2008, Francisco Reyes wrote:
| I am trying to get a distinct set of rows from 2 tables.
| After looking at someone else's query I noticed they were doing a group by
| to obtain the unique list.
|
| After comparing on multiple machines with several tables, it seems using
| group by to obtain a distinct list is substantially faster than using
| select distinct.
|
| Is there any dissadvantage of using "group by" to obtain a unique list?

Searching the archives suggests that the code related to "group by" is much
newer than the one related to "distinct" and thus might benefit from more
optimization paths.

Ciao,
Thomas

-- 
Thomas Pundt <thomas(dot)pundt(at)rp-online(dot)de> ---- http://rp-online.de/ ----



Home | Main Index | Thread Index

Privacy Policy | PostgreSQL Archives hosted by Command Prompt, Inc. | Designed by tinysofa
Copyright © 1996 – 2008 PostgreSQL Global Development Group