Re: View mechanism

Views are compiled objects. To see what was compiled, look at dba_ or all_ or user_ views. The column in these views named text shows what Oracle compiled. If you create a view as select * from tablea, where tablea contains columns a,b,c you will see in text a, b, c instead of *. Many people cannot figure out if they created a view with * then added a column and issued the command

alter view my_view recompile;

why the view still only returns three columns.

Yes, you figured out how Oracle would handle a where clause in sql and a where clause in the view. In effect a view presents a virtual table. This virtual table is effectively passed to the sql referencing the view.

cabral_at_merconet.com.br wrote:
: Hi

: If I make an select with a WHERE clause upon a view,
: how it behaves? (1)It will merge my WHERE clause with
: the view's where clause and execute the view or (2)will
: execute the view and then execute my where clause
: over the result set returned by the view?
: I think the answer is (2), because the poor performance.
: This behaviour can be changed via some server setting,
: or there is another way?

: Thank you
: Luis Cabral

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-- Received on Thu Nov 12 1998 - 15:53:23 CST