Re: Tunning Select and Where statements

Try:

  SELECT /*+ FULL */ col1,col2 FROM table1;

This will force a full table scan.

HTH,
Brian

Tom Best wrote:
>
> Yes. Look up the subject "hints" in your oracle doc. There's one that will
> force no index usage.
>
> Jay Scheiner wrote:
>
> > Is there a way to tell the query to avoid the index? I have worked on a
> > mainframe (Unisys DMSII) database where you can either process through the
> > index only (if all the values you want are in the index), through the data
> > via the index, or just through the table space itself.
> >
> > You may also reply to jxs at wolpofflaw dot com (no spam).
> >
> > Thanks.
> >
> > Riccardo Ferrari wrote in message <7u4o7v$lpk$1_at_nslave1.tin.it>...
> > >I suppose you have a B-tree index on 'age'. In this case your index is not
> > >enough selective. Sometime a full scan of the table is better than an
> > access
> > >to the index followed by an access by ROWID to the table.
> > >In the second case you have a performance improvement because you avoid the
> > >second access by rowid. The name infact is already in the index segment.
> > >If your table is really large you should try to use an hash index on age to
> > >speed up your query.
> > >Ric
Received on Mon Nov 15 1999 - 09:50:38 CST