Re: oracle 8.1.6 optimizer settings!

From: Tanel Põder <tanel_at_altavista.kom>
Date: Tue, 12 Jun 2001 20:51:22 +0200
Message-ID: <3b26646b$0$228$ba624cac@news.uninet.ee>

> Values are :


>  CHOOSE       -- Cost based optimization

>  RULE         -- Rule Based optimization

>  FIRST_ROWS   -- Genrally forces index

>  ALL_ROWS     -- Generally forces index suppression


I think first_rows generally tends to use more nested loops,
all rows uses more merge joins or hash joins, if hash joins are enabled.

Indexes aren't used if we have small enough tables + high multiblock_read_count or we will have major part of the table's records in result set.

afaik,
Tanel Poder
a DBA. Received on Tue Jun 12 2001 - 13:51:22 CDT