Re: Opinons/Philosophy on adding flags to table to reduce queries?

Agreed. But 'better' does not mean 'good'. You have to think of  pathologically sized rows to justify extra amount of resources for index access -be it bitmapped or not- in the mentioned case of 80% pass.
I'd try to divide into 'true' and 'false' parts of the original table, providing
a view '<true> union <false>' to gain access to all elements if needed. Just my 2 cents.

Alexander V. Silantiev <silantiev_at_bashkortostan.ru> schrieb in im Newsbeitrag: 9i97vn$js5$1_at_poikc.bashnet.ru...
> If cardinality of tested columns is low, it would be better to combine
 that
> columns in bitmap index (especially
> when the data in this table is fixed)
>
> Rolf Czedzak <520040398192-0001_at_t-online.de> ñîîáùèë â íîâîñòÿõ
> ñëåäóþùåå:9hsolg$3ek$07$1_at_news.t-online.com...
> > Would bitmap index lead to anything but 80% pass. I do think, that's far
 to
> > little selectivity to use an index.
> >
> > Niall Litchfield <n-litchfield_at_audit-commission.gov.uk> schrieb in im
> > Newsbeitrag: 3b419c55$0$8510$ed9e5944_at_reading.news.pipex.net...
> > > If the data is fixed would a bitmap index suffice?
> > >
> > >
> > > --
> > > Niall Litchfield
> > > Oracle DBA
> > > Audit Commission UK
> > > "Jeff Wilson" <jwilson2000_at_home.com> wrote in message
> > > news:Xgc07.288435$p33.5772965_at_news1.sttls1.wa.home.com...
> > > > What is the conventional wisdom regarding adding a boolean column to
 a
 table
> > > > that is simply the result of a test on the values in about 6 other
 columns?
> > > >
> > > > I'm dealing with large tables and my query currently involves
 conditions
 on
> > > > the values of these 6 columns. I index all of these columns, but it
 seems
> > > > like it would be much faster to simply look at a single boolean
 value.
> > > > Probably about 80% of the rows in the table pass the boolean test.
> > > >
> > > > The data in this table is fixed so I don't have to worry about an
 update
> > > > affecting theboolean.
> > > >
> > > > Would only a purist avoid something like this? Are there
 considerations
> > > > here I'm missing?
> > > >
> > > > Thanks.
> > > >
> > > > --
> > > > Jeff Wilson
> > > > jwilson2000_at_home.com
> > > > Eugene, Oregon
> > > >
> > > > (541) 684-8590
> > > >
> > > >
> > >
> > >
> > >
> > >
> >
> >
>
>
Received on Tue Jul 10 2001 - 04:34:11 CDT