On 4/13/15 8:12 PM, David G. Johnston wrote:
Hello!
Is there any non-functional difference between these two forms of Update?
WITH name AS ( SELECT )
UPDATE tbl SET ...
FROM name
WHERE tbl.id <http://tbl.id> = name.id <http://name.id>
and
UPDATE tbl SET ...
FROM ( WITH qry AS ( SELECT ) SELECT * FROM qry ) AS name
WHERE tbl.id <http://tbl.id> = name.id <http://name.id>
They both better give the same results but does the backend treat them
differently?
Does the answer to my question depend on the version of PostgreSQL?
Well, they're both ugly... but see what EXPLAIN or EXPLAIN VERBOSE shows.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general
