SCRIPT TO CHECK FOR FOREIGN KEY LOCKING ISSUES

Applies to:

Oracle Server – Enterprise Edition – Version: 7.0.16.0 to 10.2.0.5 – Release: 7.0 to 10.2
Information in this document applies to any platform.

Purpose

SCRIPT TO CHECK FOR FOREIGN KEY LOCKING ISSUES

Software Requirements/Prerequisites

Rdbms:07.0.X – 11.XX

Configuring the Script

Access Privileges:
If run as owner of objects no special priveleges required

Usage:
sqlplus / @[SCRIPTFILE]

Running the Script

PROOFREAD THIS SCRIPT BEFORE USING IT! Due to differences in the way text
editors, e-mail packages, and operating systems handle text formatting (spaces,
tabs, and carriage returns), this script may not be in an executable state
when you first receive it. Check over the script to ensure that errors of
this type are corrected.The script will produce an output file named [outputfile].
This file can be viewed in a browser or uploaded for support analysis.

Description

This script checks the current users Foreign Keys to make sure of the
following:

1) All the FK columns have indexes to prevent a possible locking

2) Checks the ORDER OF THE INDEXED COLUMNS. To prevent the locking
problem the columns MUST be indexed in the same order as the FK is
defined.

3) If the script finds a mismatch, the script reports the correct
order of columns that need to be added to prevent the locking
problem.

IMPORTANT, PLEASE NOTE

This locking problem, due to a FK column not being indexed, is discussed
in the 8x/9x Concepts Manual under Data Integrity chapter.

Starting with Oracle9i, Release 1 (9.0.1), Oracle no longer requires
a share lock on unindexed foreign keys when doing an update or delete on
the primary key. It still obtains the table-level share lock, but then
releases it immediately after obtaining it. If multiple primary keys are
update or deleted, the lock is obtained and released once for each row.

Caution

This script is provided for educational purposes only and not supported by Oracle Support Services. It has been tested internally, however, and works as documented. We do not guarantee that it will work for you, so be sure to test it in your environment before relying on it. Proofread this script before using it! Due to the differences in the way text editors, e-mail packages and operating systems handle text formatting (spaces, tabs and carriage returns), this script may not be in an executable state when you first receive it. Check over the script to ensure that errors of this type are corrected.

Script

=======
Script:
=======

———– cut ———————- cut ————– cut ————–

SET ECHO off
REM NAME:   TFSFKCHLK.SQL
REM USAGE:"@path/tfsfkchk"
REM --------------------------------------------------------------------------
REM REQUIREMENTS:
REM    None -- checks only the USER_ views
REM --------------------------------------------------------------------------
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 -------------------------------------------------------------------------
REM Main text of script follows:

drop table ck_log;

create table ck_log (
LineNum number,
LineMsg varchar2(2000));

declare
t_CONSTRAINT_TYPE            user_constraints.CONSTRAINT_TYPE%type;
t_CONSTRAINT_NAME            USER_CONSTRAINTS.CONSTRAINT_NAME%type;
t_TABLE_NAME                 USER_CONSTRAINTS.TABLE_NAME%type;
t_R_CONSTRAINT_NAME          USER_CONSTRAINTS.R_CONSTRAINT_NAME%type;
tt_CONSTRAINT_NAME           USER_CONS_COLUMNS.CONSTRAINT_NAME%type;
tt_TABLE_NAME                USER_CONS_COLUMNS.TABLE_NAME%type;
tt_COLUMN_NAME               USER_CONS_COLUMNS.COLUMN_NAME%type;
tt_POSITION                  USER_CONS_COLUMNS.POSITION%type;
tt_Dummy                     number;
tt_dummyChar                 varchar2(2000);
l_Cons_Found_Flag            VarChar2(1);
Err_TABLE_NAME               USER_CONSTRAINTS.TABLE_NAME%type;
Err_COLUMN_NAME              USER_CONS_COLUMNS.COLUMN_NAME%type;
Err_POSITION                 USER_CONS_COLUMNS.POSITION%type;

tLineNum number;

cursor UserTabs is
select table_name
from   user_tables
order by table_name;

cursor TableCons is
select CONSTRAINT_TYPE,
CONSTRAINT_NAME,
R_CONSTRAINT_NAME
from user_constraints
where OWNER = USER
and table_name = t_Table_Name
and CONSTRAINT_TYPE  = 'R'
order by TABLE_NAME, CONSTRAINT_NAME;

cursor ConColumns is
select CONSTRAINT_NAME,
TABLE_NAME,
COLUMN_NAME,
POSITION
from user_cons_columns
where OWNER = USER
and   CONSTRAINT_NAME = t_CONSTRAINT_NAME
order by POSITION;

cursor IndexColumns is
select TABLE_NAME,
COLUMN_NAME,
POSITION
from user_cons_columns
where OWNER = USER
and   CONSTRAINT_NAME = t_CONSTRAINT_NAME
order by POSITION;

DebugLevel number := 99; -- >>> 99 = dump all info`
DebugFlag varchar(1) := 'N'; -- Turn Debugging on
t_Error_Found  varchar(1);

begin

tLineNum := 1000;
open UserTabs;
LOOP
Fetch UserTabs into t_TABLE_NAME;
t_Error_Found := 'N';
exit when UserTabs%NOTFOUND;

-- Log current table
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, NULL );

tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Checking Table '||t_Table_Name);

l_Cons_Found_Flag := 'N';
open TableCons;
LOOP
FETCH TableCons INTO t_CONSTRAINT_TYPE,
t_CONSTRAINT_NAME,
t_R_CONSTRAINT_NAME;
exit when TableCons%NOTFOUND;

if ( DebugFlag = 'Y' and DebugLevel >= 99 )
then
begin
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Found CONSTRAINT_NAME = '|| t_CONSTRAINT_NAME);

tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Found CONSTRAINT_TYPE = '|| t_CONSTRAINT_TYPE);

tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Found R_CONSTRAINT_NAME = '|| t_R_CONSTRAINT_NAME);
commit;
end;
end if;

open ConColumns;
LOOP
FETCH ConColumns INTO
tt_CONSTRAINT_NAME,
tt_TABLE_NAME,
tt_COLUMN_NAME,
tt_POSITION;
exit when ConColumns%NOTFOUND;
if ( DebugFlag = 'Y' and DebugLevel >= 99 )
then
begin
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, NULL );

tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Found CONSTRAINT_NAME = '|| tt_CONSTRAINT_NAME);

tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Found TABLE_NAME = '|| tt_TABLE_NAME);

tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Found COLUMN_NAME = '|| tt_COLUMN_NAME);

tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Found POSITION = '|| tt_POSITION);
commit;
end;
end if;

begin
select 1 into tt_Dummy
from user_ind_columns
where   TABLE_NAME =  tt_TABLE_NAME
and     COLUMN_NAME = tt_COLUMN_NAME
and     COLUMN_POSITION = tt_POSITION;

if ( DebugFlag = 'Y' and DebugLevel >= 99 )
then
begin
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Row Has matching Index' );
end;
end if;
exception
when Too_Many_Rows then
if ( DebugFlag = 'Y' and DebugLevel >= 99 )
then
begin
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Row Has matching Index' );
end;
end if;

when no_data_found then
if ( DebugFlag = 'Y' and DebugLevel >= 99 )
then
begin
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'NO MATCH FOUND' );
commit;
end;
end if;

t_Error_Found := 'Y';

select distinct TABLE_NAME
into tt_dummyChar
from user_cons_columns
where OWNER = USER
and   CONSTRAINT_NAME = t_R_CONSTRAINT_NAME;

tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum, 'Changing data in table '||tt_dummyChar
||' will lock table ' ||tt_TABLE_NAME);

commit;
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum,'Create an index on table '||tt_TABLE_NAME
||' with the following columns to remove lock problem');

open IndexColumns ;
loop
Fetch IndexColumns into Err_TABLE_NAME,
Err_COLUMN_NAME,
Err_POSITION;
exit when IndexColumns%NotFound;
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum,'Column = '||Err_COLUMN_NAME||' ('||Err_POSITION||')');
end loop;
close IndexColumns;
end;
end loop;
commit;
close ConColumns;
end loop;
if ( t_Error_Found = 'N' )
then
begin
tLineNum := tLineNum + 1;
insert into ck_log ( LineNum, LineMsg ) values
( tLineNum,'No foreign key errors found');
end;
end if;
commit;
close TableCons;
end loop;
commit;
end;
/

select LineMsg
from ck_log
where LineMsg NOT LIKE 'Checking%' AND
LineMsg NOT LIKE 'No foreign key%'
order by LineNum
/

———– cut ———————- cut ————– cut ————–

Script Output

=========
Examples:
=========

LINEMSG

————————————————————————–
Changing data in table EMP will lock table DEPT
Create an index on the following columns to remove lock
problem

Column = DEPTNO (1)

Changing data in table EMP will lock table EMP
Create an index on the following columns to remove lock
problem

Column = MGR (1)

Changing data in table ITEMS will lock table ITEM_CATEGORIES
Create an index on the following columns to remove lock
problem

Column = ITEM_CAT (1)
Column = ITEM_BUS_UNIT (2)

Changing data in table ITEMS will lock table ITEM_CATEGORIES
Create an index on the following columns to remove lock
problem

Column = ITEM_CAT (1)
Column = ITEM_BUS_UNIT (2)

Changing data in table CUSTOMER will lock table ORD
Create an index on the following columns to remove lock
problem

Column = CUSTID (1)

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