Keystroke wrote:
>
> On Tue, 15 Apr 1997 08:24:08 GMT, Clark Mason <cmason_at_aai.arco.com>
> wrote:
>
> >> The view's query is not dynamic, you are building an intermediate table. A
> >> view reacts like a subquery. It always
> >> returns the same solution set regardless of what else you specify in the
> >> query. So the answer is that Oracle will first create the view will 10,000
> >> rows. Then process the rest of the query against it.
> >>
> >> That's how I understand it.
>
> in Oracle Book: \oracle\doc\server\72\svtuning.obd
> Chapt 6 - Page 1 - under heading: How Oracle Optimizes SQL Statements
> third list entry it says:
>
> view merging For a SQL statement that accesses a view,
> the optimizer often merges the query in
> the statement with that in the view and
> then optimizes the result.
>
> What is the source of the position that it returns all the data from
> the view first? Is there some flakey DBMS out there (sybase?) that
> does it this way, and everyone assumes Oracle does it that way also?
There is an optimizer hint called /* push_subq */ which will process an
Oracle view rather than merge it. We use this with varying results from
useful to useless. The optimizer seems to always get its way,
regardless.
Received on Thu Apr 17 1997 - 00:00:00 CDT
