Hello, I was thinking about what happens when I do an SQL query that names tables and joins between them that aren't used at all. For example this:
SELECT m.Sender, m.Subject FROM Message m, MessageTag mt; Does it open and read the table MessageTag at all? Also, what happens in a more complex example where a more explicit join is done but never used: SELECT m.Sender, m.Subject FROM Message m NATURAL JOIN MessageTag mt; Or: SELECT m.Sender, m.Subject FROM Message m LEFT JOIN MessageTag mt USING (MessageId); Does it impact performance when the join appears in the query or will the optimiser remove it? I haven't seen anything about this in the "query optimiser overview" documentation. -- Yves Goergen "LonelyPixel" <[EMAIL PROTECTED]> Visit my web laboratory at http://beta.unclassified.de ----------------------------------------------------------------------------- To unsubscribe, send email to [EMAIL PROTECTED] -----------------------------------------------------------------------------
