Hi Anup,
You can encourage Oracle to read the tables in a particular order by using
the ORDERED hint. For example, if you wanted the following query to have
tableb as the driving table:
SELECT /*+ ORDERED */ col1,col2
FROM tableb, tablea, tablec
WHERE ...
Will cause Oracle to read tableb first
Basically, that's correct. Oracle _generally_ does a good job choosing an
excellent execution path. In some cases better than can be achieved through
the Rule-based optimizer...However there's that 0.5% that we have to
manually tune. Check out the section on HINTS in your Oracle Docs...you have
a
Hi there ,
Thanks for the reply .
I am in Cost Based Optimizer ( we all will be now a days ) .
Does that mean , if I want to know ( or decide ) while writting the query , my
driving table , Its not possible ???
If I have a good idea ( size of data in tables , indexes etc.) about the
tables invol
First question is whether you're in Cost Based or Rule Based optimization.
In RBO you are correct that it will read tables right to left unless
instructed otherwise by a hint.
In CBO, Oracle will choose what it thinks is 'best', which most of the time,
but not all of the time :), will be true.
J