Hi,
following script may help you. The brief description of the script is
as follows.
--------------------------------------------------------------------------
REM This file checks the current users Foreign Keys to make sure of the
REM following:
REM
REM 1) All the FK columns are have indexes to prevent a possible locking
REM problem that can slow down the database.
REM
REM 2) Checks the ORDER OF THE INDEXED COLUMNS. To prevent the locking
REM problem the columns MUST be index in the same order as the FK is
REM defined.
REM
REM 3) If the script finds and miss match the script reports the correct
REM order of columns that need to be added to prevent the locking
REM problem.
REM
REM
REM
REM
-------------------------------------------------------------------------
(See attached file: foreign_key_locks.sql)
"Krishnaswamy, Ranganath"
<[EMAIL PROTECTED] To: Multiple
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global.com> cc:
Sent by: [EMAIL PROTECTED] Subject: Foreign key
indexes on individual columns or multiple columns
01/14/2003 12:29 PM
Please respond to ORACLE-L
Hi List,
I have a table by name Benchmark_hdr with the following
columns:
BENCHMARK_HDR_ID NUMBER NOT NULL
CALENDAR_TYPE CHAR (1),
UOM VARCHAR2 (10),
CALENDAR_PORT CHAR (1),
CUSTOMER_MOT_ID NUMBER NOT NULL
RESP_PARTY_NAME VARCHAR2 (10),
FROM_EVENT NUMBER,
TO_EVENT NUMBER,
LAST_UPDATED DATE
I have created foreign key constraints using the below commands:
ALTER TABLE BENCHMARK_HDR ADD CONSTRAINT BENCHAMRK_HDR_CUSTOMERESP_FK
FOREIGN KEY (RESP_PARTY_NAME, CUSTOMER_MOT_ID)
REFERENCES XM.CUSTOMER_RESPONSIBLE_PARTY (RESP_PARTY_NAME,
CUSTOMER_MOT_ID) ;
ALTER TABLE BENCHMARK_HDR ADD CONSTRAINT BENCHAMRK_HDR_CUSTOMEREVENT_FK
FOREIGN KEY (FROM_EVENT)
REFERENCES XM.CUSTOMER_EVENT (CUSTOMER_EVENT_ID) ON DELETE CASCADE;
ALTER TABLE BENCHMARK_HDR ADD CONSTRAINT BENCHMARK_HDR_CUSTOMEREVENT_FK
FOREIGN KEY (TO_EVENT)
REFERENCES XM.CUSTOMER_EVENT (CUSTOMER_EVENT_ID) ON DELETE CASCADE;
The foreign keys need to be indexed so that the child table is not locked
when a record in the parent table is being updated or deleted. If the
foreign keys are indexed the corresponding child record or records are only
locked when the parent table record is being updated or deleted. In this
context I would like to seek the advice of the list as to whether I should
create indexes on individual foreign keys or should I create one or more
composite index(es) on foreign keys? If I need to create a composite index
on which columns should I base my index on? Could anybody advise me on
this
with the reasons for following that particular approach? Any help in this
regard is very much appreciated.
Thanks and Regards,
Ranganath
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foreign_key_locks.sql
Description: Binary data
