speed of query - help
Date: 1999/10/22
Message-ID: <7uppo9$sup$1_at_nnrp1.deja.com>#1/1
Let's say I have a sql query that looks at 5 tables ...
Assuming that it's possible, I always thought that joining the
smaller tables together first would speed the query. Once Table A-D are
joined, that entire result set is then joined with Table E. Only one
large join is performed.
However, after reading the Oracle 7 Server SQL Reference Manual, page
4-21 states that "the optimizer determines the order in which Oracle7
joins tables based on the join conditions, indexes on the tables, and,
in the case of the cost-based optimization approach, statistics for the
tables". So, I guess this means that the order that you list the tables
in the where clause doesn't matter (btw I'm using the CBO).
Does anybody have any insight regarding this topic?
--
-Keith
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Table A - 100 rows
Table B - 200 rows
Table C - 300 rows
Table D - 150 rows
Table E - 1000000 rows
Before you buy.
Received on Fri Oct 22 1999 - 00:00:00 CEST