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 recipients of list ORACLE-L <[EMAIL PROTECTED]> 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 WARNING: The information in this message is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorised. If you are not the intended recipient, any disclosure, copying, or distribution of the message, or any action or omission taken by you in reliance on it, is prohibited and may be unlawful. Please immediately contact the sender if you have received this message in error. Thank you. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Krishnaswamy, Ranganath INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
foreign_key_locks.sql
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