Orest Kozyar wrote:
What I am wondering is whether the database first eliminate all rows in tableA that don't meet the criteria before performing the join, or does it perform the join first then eliminate all records that don't meet the criteria?
If you use "EXPLAIN SELECT ..." then PostgreSQL will tell you how it's going to execute your query. If you use "EXPLAIN ANALYZE SELECT ..." it will tell you what it actually did too. See manuals and google for details and discussion.
Oh, and if you don't know about VACUUM and ANALYZE you'll probably want to read up on those too.
-- Richard Huxton Archonet Ltd
