subject:"RE\: Are too many Foreign Keys in one table bad\?"

Re: Are too many Foreign Keys in one table bad?

2003-01-07 Thread Jonathan Lewis

And apart from the differences in cost on the simple test, you also remove the information about uniqueness and non-nullability if you don't declare the primary key, and this has an impact on the optimizer's decision tree. Bear in mind, also, that Oracle will rarely do a tablescan on the inner

RE: Are too many Foreign Keys in one table bad?

2003-01-07 Thread Burke, William F (Bill)

A couple of other thoughts depending on the size of the table with the large number of foreign keys (I may have missed the exact row counts), you might want to consider bitmaps on the foreign keys in the main table depending on the uniqueness of the data. Also, if the foreign key tables are

RE: Are too many Foreign Keys in one table bad?

2003-01-07 Thread Gregory Norris

To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] wisernet100@y cc: ahoo.comSubject: Re: Are too many Foreign Keys in one table bad

RE: Are too many Foreign Keys in one table bad?

2003-01-07 Thread Fink, Dan

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RE: Are too many Foreign Keys in one table bad?

2003-01-07 Thread Fink, Dan

Gregory, There are several things to consider since you are still at the design phase. This table sounds like a great candidate for denormalization. Is this an OLTP or OLAP system? How static are the values in the reftables? If the reftables are static and contain very few values, consider

RE: Are too many Foreign Keys in one table bad?

2003-01-07 Thread Rachel Carmichael

: Re: Are too many Foreign Keys in one table bad? Sent by: [EMAIL PROTECTED

Re: Are too many Foreign Keys in one table bad?

2003-01-07 Thread Jared . Still

[EMAIL PROTECTED] cc: Subject:Re: Are too many Foreign Keys in one table bad? All, Point well taken (both Rachel's and Jared's). I should have said (and was even thinking - although the brain and hands sometimes act independently) might not be worth indexing. It sounds like

Re: Are too many Foreign Keys in one table bad?

2003-01-06 Thread BigP

If the code is unique its not a problem. Only part that can give trouble is u r allowing to update code in reftable . That's not coool . - Original Message - To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Sent: Monday, January 06, 2003 12:03 PM I am designing some tables

Re: Are too many Foreign Keys in one table bad?

2003-01-06 Thread Mark Richard

Greg, I don't think Oracle will have a real problem with 15 tables or 1,000 rows. If the ref tables are quite small then they won't even be worth indexing - Oracle will just read the entire table at one anyway. You might want to tell Oracle to CACHE the reference tables, although I don't think

Re: Are too many Foreign Keys in one table bad?

2003-01-06 Thread Rachel Carmichael

Mark, Based on the presentation and testing Dan Fink did for the last NYOUG meeting, it's possible that the ref tables SHOULD be indexed, and that it will help performance to index them. Rachel --- Mark Richard [EMAIL PROTECTED] wrote: Greg, I don't think Oracle will have a real problem

Re: Are too many Foreign Keys in one table bad?

2003-01-06 Thread Jared . Still

I don't think Oracle will have a real problem with 15 tables or 1,000 rows. If the ref tables are quite small then they won't even be worth indexing - Oracle will just read the entire table at one anyway. Not necessarily. There can be quite a difference between using an index on a small