FillSchema picks too many primary key columns

Question

I don't know whether this is an ODP.NET error or a Microsoft error.
Oracle9i Release 9.2.0.1.0
ODP.NET 9.2.0.4
.NET Framework 1.1
Create a table with one primary key column and one unique column and name the primary key column like the unique column with the suffix "_ID":
CREATE TABLE t_bib_uebertrag_kap(
&nbsp kapazitaet_id NUMBER(8) NOT NULL
&nbsp&nbsp CONSTRAINT pk_kapa primary key,
&nbsp kapazitaet VARCHAR2(15) NOT NULL
&nbsp&nbsp CONSTRAINT a_un_kapa unique,
&nbsp geschwindigkeit NUMBER(12) NOT NULL,
&nbsp bemerkung VARCHAR2(255)
After calling FillSchema on this table the PrimaryKey property of the DataTable contains 2 columns: KAPAZITAET_ID and KAPAZITAET.
The same happens with other tables and similar column names
R. Lüthke

Answer 1

Tony, I'm gonna find time to try this because I was thinking it probably would be a double check.
BUT... Oracle is written in C, and I imagine the extra check as a simple if comparison for the new value versus a constant NULL value. Kind of like checking for end of string. It's already doing things like checking datatypes and that as it inserts data, and I don't think this additional check (if it even exists) would add any significant overhead.
But unless I find a much larger performance hit than I expect, I'm gonna stick with creating the NOT NULL's explicitly. Good data modelling trumps small performance tricks for me.
My main worry is if/when somebody removes the primary key constraint (such as the example above where they might do a CREATE TABLE x AS SELECT * FROM y). Or if the data model gets updated to where the primary key becomes just a unique key, then the NOT NULL goes away when it shouldn't. I don't like basic table and column properties changing.
Okay.. test done. Ran about 31,000 records from dba_tables through an insert into two tables, both with primary keys and one with explicit NOT NULLs. No measurable difference in stats detected.
With NOT NULL and PRIMARY KEY:
call count cpu elapsed disk query current rows
Parse 1 0.35 0.35 0 0 0 0
Execute 1 1.88 1.83 0 24792 35887 30954
Fetch 0 0.00 0.00 0 0 0 0
total 2 2.24 2.18 0 24792 35887 30954
Now with only PRIMARY KEY.
call count cpu elapsed disk query current rows
Parse 1 0.37 0.36 0 0 0 0
Execute 1 1.87 1.83 0 24792 35887 30954
Fetch 0 0.00 0.00 0 0 0 0
total 2 2.24 2.19 0 24792 35887 30954