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Home -> Community -> Usenet -> c.d.o.misc -> Re: Proper database design for best performance?
jbrychka_at_my-deja.com wrote:
>
> That is a great idea. Now I need to figure out how I should set up
> some type of data integrety check since I'm allowing nulls in this
> column.
>
> Thanks
>
> In article <952035101.24230.0.pluto.d4ee154e_at_news.demon.nl>,
> "Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote:
> > Use char(1) containing NULL for processed rows and anything for
> > non-processed rows. If all is well, NULL still won't be go into the
> index,
> > so the index will be very small.
> >
> > Hth,
> >
> > Sybrand Bakker, Oracle DBA
> >
> > <jbrychka_at_my-deja.com> wrote in message news:89mg61$132
> $1_at_nnrp1.deja.com...
> > > I would like some ideas on the best way to set up data for fast
> access.
> > >
> > > I have a very large table that I look up for records that have not
> been
> > > processed. The query would look something like this:
> > >
> > > select column_a
> > > from table
> > > where date_column is NULL
> > >
> > > This type of query cannot use an index so it is very slow. To get
> > > around the index issue I was thinking of defaulting this
> date_column to
> > > a specific date that I would then put in my query. Something like
> this:
> > >
> > > select column_a
> > > from table
> > > where date_column = :default_date
> > >
> > > This way I could use an index. The only thing I don't like about
> this
> > > is that I am putting this bogus date value in the column.
> > >
> > > Another option is to add an indicator column that would default
> to "N"
> > > for new records and then get updated to "Y" when processed. The
> issue
> > > I have with this is that I still need the date column to know when
> it
> > > is processed so now I have two columns instead of just one which
> causes
> > > the table to use more table space.
> > >
> > > If anybody has any opinion on this or other alternatives, I would
> like
> > > to hear about it.
> > >
> > > Thanks,
> > >
> > > Jim
> > >
> > >
> > > Sent via Deja.com http://www.deja.com/
> > > Before you buy.
> >
> >
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
You could stick a trigger on the table so that the column is automatically populated when dates come in.
HTH
--
We are born naked, wet and hungry...then things get worse Received on Fri Mar 03 2000 - 08:10:45 CST
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