Re: Normalizing vs. Denormalizing

Will Kooiman (wkooiman_at_csac.com) wrote:

: Be very careful about denormalizing this design. In almost every case, a
: normalized design will outperform a denomalized design.

Where do you get this idea?

: Oracle actually joins tables very fast. I have had several systems that

But it still has to join them. If you have GBs of data, that takes time.

: regularly joined 15-20 tables together that had response times less than a
: second. One system ran on a "slow" RS 6000 with 300,000+ records.

Which is a pretty small database, much of which will probably stay in memory.

: Conversely, EVERY system I have ever worked on that had performance
: problems was "denormalized for performance".

Pretty general statement.

: Also, Oracle does block i/o, not record i/o. Normalized databases tend to
: have more records per block due to data not being duplicated. This
: translates into LESS i/o.

Has no impact, since both normal and denormal use the same IO system.

: This is a huge topic that can only be solved with lots of debates and/or
: tests.

Agreed.

--
Bob Stewart                     ASE
(310) 335-7152                  Air Transportation Division
bob_at_latcost1.alaao.ats.eds.com

I am definitely NOT speaking for EDS.