RE: naming conventions (constraints and indexes)
- From: <Joel.Patterson@xxxxxxxxxxx>
- To: <Hemant.Chitale@xxxxxx>
- Date: Thu, 10 Nov 2011 09:09:06 -0500
Interesting, and I have a couple observations from these urls.
-- Yes, the ALTER TABLE ... DROP CONSTRAINT does have a "KEEP INDEX" clause.
-- Hemant gives an example of the index and constraint name being different,
but that when you drop the constraint, the ORA-0001 returns the index name.
However, I interpret the results where, when they are the same name, that the
index name is still returned... since the constraint was dropped, why would it
be the constraint name, (they're the same -- I say it is the index name still).
I'm just not too sure how much it matters that the index be independent of the
constraint. Indeed it seems like a good idea ... However, Freek points out
that the using index clause has a side affect where if another index is present
that can support the constraint, then oracle will not recreate the one defined
in the using index clause during import. (kind of news to me though -- but it
seems like almost a redundant index situation).
Joel Patterson
Database Administrator
904 727-2546
-----Original Message-----
From: Chitale, Hemant Krishnarao [mailto:Hemant.Chitale@xxxxxx]
Sent: Wednesday, November 09, 2011 11:09 PM
To: Patterson, Joel
Cc: oracle-l@xxxxxxxxxxxxx
Subject: RE: naming conventions (constraints and indexes)
I prefer to create the Index *before* defining the constraint.
That way, the Index is independent of the constraint.
So
a) the Index is preserved when I drop the constraint
b) the Index can be non-Unique
c) for composite definitions, the columns need not be in the same "order" in
the Index definition
http://hemantoracledba.blogspot.com/2010/07/preserving-index-when-dropping.html
and
http://hemantoracledba.blogspot.com/2011/03/primary-key-and-index.html
Hemant K Chitale
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Joel.Patterson@xxxxxxxxxxx
Sent: Thursday, November 10, 2011 3:21 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: naming conventions (constraints and indexes)
....deleted ....
CREATE TABLE EXAMPLE_TABLE (
PRIM_COL number constraint EXAMPLE_TABLE_PK primary key
using index ( CREATE INDEX EXAMPLE_TABLE_PX ON
EXAMPLE_TABLE(PRIM_COL)),
UNIQ_COL number constraint EXAMPLE_TABLE_UNIQ_COL_UK UNIQUE
using index ( create index EXAMPLE_TABLE_UNIQ_COL_UX on
EXAMPLE_TABLE(UNIQ_COL)),
junk varchar2(10)
);
select table_name, constraint_name, constraint_type, index_name
from user_constraints where table_name = 'EXAMPLE_TABLE';
TABLE_NAME CONSTRAINT_NAME C INDEX_NAME
------------------------- ------------------------- ------------------
EXAMPLE_TABLE EXAMPLE_TABLE_PK P EXAMPLE_TABLE_PX
EXAMPLE_TABLE EXAMPLE_TABLE_UNIQ_COL_UK U EXAMPLE_TABLE_UNIQ_COL_UX
DBMON @ COSDEV> select table_name, index_name from user_indexes where
table_name = 'EXAMPLE_TABL
TABLE_NAME INDEX_NAME
------------------------------ ------------------------------
EXAMPLE_TABLE EXAMPLE_TABLE_PX
EXAMPLE_TABLE EXAMPLE_TABLE_UNIQ_COL_UX
Joel Patterson
Database Administrator
904 727-2546
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