Oracle FAQ | Your Portal to the Oracle Knowledge Grid |
Home -> Community -> Usenet -> c.d.o.server -> Re: View performance
Jackie Marino wrote:
>
> stegri_at_rocketmail.com wrote:
> >
> > Does anybody know if using views instead of tables affects performance?
> > I've heard that view are in some way 'compiled' (although I don't understand
> > what is there to be compiled) and are even more efficient than retriving
> > columns as 'normal' select-stmts.
> >
> > /Stelios Grigoriadis
>
> Views on tables gains performance in less i/o hits on the actual tables.
> Instead of hitting the tables with SQL, you are just hitting a view
> or picture of the tables. The SQL is only performed once on compilation
> of the view and then are stored in the data dictionary just like
> procedures and functions. You can manually recompile a view. For
> example, if names change in the table it references.
Jackie,
I am not sure I understand your answer. Are you saying that views are a copy, or snapshot of the involved tables? I do not think that is correct. Any access into a view is also access into the view's table(s), so I do not see where there is any obvious efficiency benefit ... that is, relative to i/o hits. My understanding of a view is that it is a convenient mechanism to perform a SELECT on one or more tables, without actually having to key the statement; rather, its definition is stored and available any time a view is referenced. A configurable window into a table-set, you might say.
Yours,
Geoff Houck
systems hk
hksys_at_teleport.com
http://www.teleport.com/~hksys
Received on Thu May 28 1998 - 18:09:41 CDT