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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Limits on referential integrity
Cherie - This is an OLTP application. I haven't received the schema yet. The performance goal is a good question, and I will ask it to the group when I find a good opportunity. Basically, they are looking for "reasonable" response times for on-line users.
The development manager keeps saying that everything is still very preliminary, but they want to go ahead and create a schema so that they can start playing around with code. My cynical DBA side says that preliminary stuff tends to freeze in place pretty quickly.
Basically, when you review a model, how many constraints on a table
do you have to see to before you say "good grief, what a mess!". Or are
there more critical points, like how many levels of table hierarchy, that
are more important?
Thanks for your questions, because you have given me more issues to
consider.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-----Original Message-----
Sent: Tuesday, January 22, 2002 6:46 AM
To: Multiple recipients of list ORACLE-L
Dennis,
How many constraints are you talking about? About how many constraints
per table?
What kind of app is it? OLAP? Data Warehouse?
What kind of performance requirements have been set?
Cherie Machler
Oracle DBA
Gelco Information Network
DENNIS WILLIAMS
<DWILLIAMS_at_LIFE To: Multiple recipients of
list ORACLE-L <ORACLE-L_at_fatcity.com>
TOUCH.COM> cc:
Sent by: Subject: RE: Limits on
referential integrity
root_at_fatcity.co
m
01/21/02 04:35
PM
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to ORACLE-L
Jared - I wasn't clear, but then again it is Monday. I have a team of
inexperienced developers starting a big, new Java application. They have a
good, experienced data model consultant helping them create the data model.
They are eager to include referential integrity. So eager it has me a
little
worried. My question: "Is there too much of a good thing?". In Oracle 7,
sometimes sites would remove RI to ensure good performance (we are starting
this project on Oracle9i). Has anyone encountered problems with too many
constraints? Any guidelines you use with developers? Thanks.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-----Original Message-----
Sent: Monday, January 21, 2002 4:16 PM
To: Multiple recipients of list ORACLE-L
I would be you lunch that what they are implementing in their code is not actually RI. They may be implementing code to ensure things get inserted in the right order, and that child rows have a parent.
This is a very weak form of RI. Oracle is very good at implementing RI, and it is not dependent on an application. RI in the database is the route to choose unless there is some good reason not to.
RI in the database will prevent orphaned data created through updates, deletes or even ( gasp! ) bugs in the app.
Programmers tend to dislike RI in the database because it forces them to maintain data integrity in a transaction. This is not a bad thing, it just forces them to have a good understanding of their transactions.
Point out to them that it is less code to write as well. :)
Jared
DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Sent by: root_at_fatcity.com
01/21/02 01:35 PM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
cc:
Subject: Limits on referential integrity
How much referential integrity should be implemented in Oracle? We are
starting a large new Java project. Our current applications keep their
referential integrity inside their own dictionary, so I haven't had to
deal
much with referential integrity recently. Can there be too much of a good
thing? What guidelines do you tend to use? At this point the developers
are
designing the data model so they are busily linking all the little boxes.
My
attitude at this point is "implement what you've got and if there are
performance problems we'll deal with them when they arise". Can anyone
give
me a better motto?
Thanks.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
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