Re: OPTIMIZER_MODE ???

From: InDfw <in_dfw_at_hotmail.com>
Date: 1998/01/18
Message-ID: <69u3e9$e08@mtinsc02.worldnet.att.net>#1/1

Nabil,

The optimizer mode can be seen by selecting from v$parameter where name = 'optimizer_mode'.
The default is "CHOOSE". In the "CHOOSE" mode, Oracle will use the cost-based optimzer
if the tables have been analyzed. If the tables have not been analyzed, then the rule-based
optimzer is used. The rule-based optimizer will be used if the hint /* RULE */ is placed in the
SQL statement, and also if the optimizer mode is set to "RULE". You can analyze the
tables by performing the statement; analyze table xyz compute statistics. One way to
see if a table has been analyzed is to see if the column num_rows has been populated in
dba_tables.

Hope this helps...

Phil Cook
Certified Oracle DBA Received on Sun Jan 18 1998 - 00:00:00 CST