Re: Wait a Minute! RE:A technical question about VIEWS

Subject: Re: Wait a Minute! RE:A technical question about VIEWS From: tkyte_at_us.oracle.com (Thomas Kyte)
Date: Mon, 14 Apr 1997 14:24:29 GMT
Message-ID: <33533d8f.2635439_at_newshost>

On Mon, 14 Apr 1997 00:52:05 GMT, keystrk_at_feist.com (Keystroke) wrote:

>On 13 Apr 1997 17:15:29 GMT, "Olen" <orkline_at_txdirect.net> 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.
>
>Wait a minute! I am a fan of Oracle, but this doesn't make sense!
>How can _ANY_ DBMS make a claim to be production-worthy and _NOT_ take
>into consideration the rest of a query when a view is used in a query
>when building the first result set? How else can it know how to
>optimize the comepete querry?
>

Queries on views can be merged with the view query. If the view was created using aggregate functions then the query cannot be merged with the view query. Almost most other times the query would be merged. An explain plan on the query would show you exactly what is happening.

The No_MERGE hint forces oracle not to integrate the queries

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Abhijit Bhattacharya