Re: Use of nulls in single character flag fields
From: Brian Everett <beverett_at_earthlink.net>
Date: 1996/11/19
Message-ID: <32922024.25980437_at_news.MNSINC.COM>#1/1
Date: 1996/11/19
Message-ID: <32922024.25980437_at_news.MNSINC.COM>#1/1
Nulls can cause problems with retrievals but they can be used to
increase performance.
If you had a table of 20 million records and you were just
interested in records that were changed ...say yesterday...you could
flag just thoughs records and leave the others null. The index would
be very small compared to what would be necessary to flag all records.
Once you processed them you could 'null out' the field and be ready
for the next batch.
Good Luck! Brian_RestonVA
ncronin <ncronin_at_tcdi.ie> wrote:
>HiReceived on Tue Nov 19 1996 - 00:00:00 CET
> We have some conflicting desgin views at our site. Some
> people believe use of nulls for flags is fine as you can
> use NVL(...) to convert when retrieving. I believe flags
> should be non-null for clarity, better performance when
> indexed and you don't have to remember to use NVL all the
> time. Also I'm not sure if there is a performance penalty
> from using NVL(...). Any views on this simple matter from
> the database designers of you ??
> Noel (ncronin_at_tcd.ie)