Causes of ORA-6502 Errors (PL/SQL: numeric or value error)

 

1) A common reason for this error can be when there is a mismatch between the data type of the variable and the value that is being assigned to it. For Example: Assigning character value to a numeric data type or assigning more value to a variable than it can hold. 

2) However its interesting that this issue can be caused by the mismatch between the client side NLS_LANG and NLS_CHARACTERSET of the database.

So the thing is when there is a mismatch between client side character set NLS_LANG and the database character set NLS_CHARACTERSET this can occur. When working with UNICODE database (UTF8/AL32UTF8), make sure that:

The NLS_LANG is not set at the client side. When NLS_LANG is not set, it will use database character set.

If NLS_LANG is set, then make sure PL/SQL bind variables is declared with enough buffer size so that the data conversion does not fail.

Some common code related issues are shown below:

SET SERVEROUTPUT ON

DECLARE

  V_VAR1 VARCHAR2(10);

  V_VAR2 NUMBER;

BEGIN

  V_VAR2 := 'MIKE';        /* VALID ORA-6502 */

  V_VAR1 := 'ABCDEFGHIKL'; /* VALID ORA-6502 */

END;

/

SET SERVEROUTPUT ON

DECLARE

  V_VAR1 VARCHAR2(3);

BEGIN

  SELECT 'ABCD' INTO V_VAR1 FROM DUAL;

END;

/

CREATE OR REPLACE FUNCTION

TEST_6502_ERROR

RETURN VARCHAR2

AS

BEGIN

   RETURN 'ASDF';

END;

/

SET SERVEROUTPUT ON

DECLARE

  V_GET_VALUE VARCHAR2(3);

BEGIN

  V_GET_VALUE := TEST_6502_ERROR;

END;

/

Exadata Storage : Grid disks based on the OFFSETs.

The Cells storage servers in Exadata offer the capability to create grid disks based on their offsets, Create the new grid disks in the order BASED ON THE OFFSET, using the sizes shown from the command list griddisk attributes name,size,offset.  

Lets see how we can do it : 

An example :

CellCLI> create griddisk DATA_CD_07_<Host Name> celldisk=CD_07_<Host Name>,size=220G

CellCLI> create griddisk RECO_CD_07_<Host Name> celldisk=CD_07_<Host Name>,size=308.6875G

CellCLI> create griddisk SYSTEMDG_CD_07_<Host Name> celldisk=CD_07_<Host Name>,size=29.125G

Run the previous query on the new grid disks and make sure all the offsets are matching (in the third column):

CellCLI> list griddisk where celldisk=CD_07_<Host Name> attributes name,size,offset

         DATA_CD_07_<Host Name>                 220G                32M

         RECO_CD_07_<Host Name>                 308.6875G           220.046875G

         SYSTEMDG_CD_07_<Host Name>             29.125G             528.734375G

 At the ASM level, the old disk was likely dropped because the disk drop timer has expired.  Log into +ASM1 instance and add the new disk.  Set the rebalance power higher (11) to perform faster and specify the failgroup if the default (name of Storage Server) is not used.

sql> alter diskgroup data drop disk DATA_CD_07_<Host Name> force;

sql> alter diskgroup data add {failgroup <FAILGROUP>} disk 'o/*/DATA_CD_07_<Host Name>' rebalance power 11;

Do the same for RECO and SYSTEMDG from a different ASM instance (to balance the work) or wait until DATA finishes on +ASM1.

If after disk replacement old celldisk and griddidsk are in state proactive failure or any other that prevents them from being deleted, try the following:

celcli> ALTER CELL RESTART SERVICES cellsrv

celcli> alter lun {lun number} reenable force

for example :

celcli> alter lun 0_0 reenable force

After this, delete cell and griddisks that corresponds to the physical disk

(it may be even done automatically).

Next, create cell disk and griddisk.

Finally after griddisks are created they should be presented in ASM but marked as candidates, but will need to be enabled. 

Resolving error RMAN-06149: cannot BACKUP DATABASE in NOARCHIVELOG mode

  

Error RMAN-06149: cannot BACKUP DATABASE in NOARCHIVELOG mode: 

This error comes when database is not in archivelog mode, in order to resolve this lets see how it can be done :

[oracle@node2 ~]$ rman target/

Recovery Manager: Release 21.0.0.0.0 - Production on Fri Sep 30 01:17:37 2022

Version 21.3.0.0.0

Copyright (c) 1982, 2021, Oracle and/or its affiliates.  All rights reserved.

connected to target database: ORCL:PDB1 (DBID=3054857248)

RMAN> backup database;

Starting backup at 30-SEP-22

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=467 device type=DISK

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of backup command at 09/30/2022 01:17:42

RMAN-06149: cannot BACKUP DATABASE in NOARCHIVELOG mode

RMAN> exit

Recovery Manager complete.

[oracle@node2 ~]$ sqlplus / as sysdba

SQL*Plus: Release 21.0.0.0.0 - Production on Fri Sep 30 01:17:49 2022

Version 21.3.0.0.0

Copyright (c) 1982, 2021, Oracle.  All rights reserved.

Connected to:

Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production

Version 21.3.0.0.0

SQL> shu immediate

Pluggable Database closed.

SQL> exit

Disconnected from Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production

Version 21.3.0.0.0

[oracle@node2 ~]$ unset ORACLE_PDB_SID

[oracle@node2 ~]$ sqlplus / as sysdba

SQL*Plus: Release 21.0.0.0.0 - Production on Fri Sep 30 01:18:04 2022

Version 21.3.0.0.0

Copyright (c) 1982, 2021, Oracle.  All rights reserved.

Connected to:

Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production

Version 21.3.0.0.0

SQL> shu immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup mount

ORACLE instance started.

Total System Global Area 1073740680 bytes

Fixed Size                  9694088 bytes

Variable Size             301989888 bytes

Database Buffers          759169024 bytes

Redo Buffers                2887680 bytes

Database mounted.

SQL> alter database archivelog;

Database altered.

SQL> alter database open;

Database altered.

SQL> show pdbs;

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED

---------- ------------------------------ ---------- ----------

         2 PDB$SEED                       READ ONLY  NO

         3 PDB1                           READ WRITE NO

SQL> archive log list

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     3

Next log sequence to archive   5

Current log sequence           5

SQL> exit

Disconnected from Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production

Version 21.3.0.0.0

[oracle@node2 ~]$ rman target/

Recovery Manager: Release 21.0.0.0.0 - Production on Fri Sep 30 01:20:14 2022

Version 21.3.0.0.0

Copyright (c) 1982, 2021, Oracle and/or its affiliates.  All rights reserved.

connected to target database: ORCL (DBID=1644501746)

RMAN> backup database;

Starting backup at 30-SEP-22

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=456 device type=DISK

channel ORA_DISK_1: starting full datafile backup set

channel ORA_DISK_1: specifying datafile(s) in backup set

input datafile file number=00001 name=/u01/app/oracle/oradata/ORCL/system01.dbf

input datafile file number=00003 name=/u01/app/oracle/oradata/ORCL/sysaux01.dbf

input datafile file number=00004 name=/u01/app/oracle/oradata/ORCL/undotbs01.dbf

input datafile file number=00007 name=/u01/app/oracle/oradata/ORCL/users01.dbf

channel ORA_DISK_1: starting piece 1 at 30-SEP-22

channel ORA_DISK_1: finished piece 1 at 30-SEP-22

piece handle=/u01/app/oracle/fast_recovery_area/ORCL/backupset/2022_09_30/o1_mf_nnndf_TAG20220930T012018_kmcxqtjt_.bkp tag=TAG20220930T012018 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:45

channel ORA_DISK_1: starting full datafile backup set

channel ORA_DISK_1: specifying datafile(s) in backup set

input datafile file number=00010 name=/u01/app/oracle/oradata/ORCL/pdb1/sysaux01.dbf

input datafile file number=00009 name=/u01/app/oracle/oradata/ORCL/pdb1/system01.dbf

input datafile file number=00011 name=/u01/app/oracle/oradata/ORCL/pdb1/undotbs01.dbf

input datafile file number=00012 name=/u01/app/oracle/oradata/ORCL/pdb1/users01.dbf

channel ORA_DISK_1: starting piece 1 at 30-SEP-22

channel ORA_DISK_1: finished piece 1 at 30-SEP-22

piece handle=/u01/app/oracle/fast_recovery_area/ORCL/E9D6636086CE3A62E0538DC909C0CE7C/backupset/2022_09_30/o1_mf_nnndf_TAG20220930T012018_kmcxs7p8_.bkp tag=TAG20220930T012018 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:15

channel ORA_DISK_1: starting full datafile backup set

channel ORA_DISK_1: specifying datafile(s) in backup set

input datafile file number=00006 name=/u01/app/oracle/oradata/ORCL/pdbseed/sysaux01.dbf

input datafile file number=00005 name=/u01/app/oracle/oradata/ORCL/pdbseed/system01.dbf

input datafile file number=00008 name=/u01/app/oracle/oradata/ORCL/pdbseed/undotbs01.dbf

channel ORA_DISK_1: starting piece 1 at 30-SEP-22

channel ORA_DISK_1: finished piece 1 at 30-SEP-22

piece handle=/u01/app/oracle/fast_recovery_area/ORCL/E9D64E6E932B35C5E0538DC909C025DE/backupset/2022_09_30/o1_mf_nnndf_TAG20220930T012018_kmcxsprj_.bkp tag=TAG20220930T012018 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:03

Finished backup at 30-SEP-22

Starting Control File and SPFILE Autobackup at 30-SEP-22

piece handle=/u01/app/oracle/fast_recovery_area/ORCL/autobackup/2022_09_30/o1_mf_s_1116724881_kmcxssyx_.bkp comment=NONE

Finished Control File and SPFILE Autobackup at 30-SEP-22

>> Backup completed successfully now.

How REGEXP_LIKE Condition works in Oracle database

REGEXP_LIKE is similar to the LIKE condition, except REGEXP_LIKE performs regular expression matching instead of the simple pattern matching performed by LIKE. This condition evaluates strings using characters as defined by the input character set.

SQL> select * from scott.emp;

     EMPNO FIRST_NAME           LAST_NAME                SALARY       COMM HIREDATE

---------- -------------------- -------------------- ---------- ---------- ---------

       101 Scott                Tiger                      2000         10 30-SEP-22

       102 John                 Smith                      2000         10 30-SEP-22

       103 Ram                  Hari                       2000         10 30-SEP-22

       104 Rakesh               Sharma                     4000         10 30-SEP-22

Lets say if we want find all employees whose first_name starts with R. Here is how you will do it :

SQL>  select * from scott.emp where regexp_like(FIRST_NAME,'^R');

     EMPNO FIRST_NAME           LAST_NAME                SALARY       COMM HIREDATE

---------- -------------------- -------------------- ---------- ---------- ---------

       103 Ram                  Hari                       2000         10 30-SEP-22

       104 Rakesh               Sharma                     4000         10 30-SEP-22

Lets say if we want find all employees whose first_name starts with R but 'a' in the middle and m at the end, note here the use of paranthesis and $ sign for middle and last alphabet. Here is how you will do it :

SQL>  select * from scott.emp where regexp_like(FIRST_NAME,'^R(a)m$');

     EMPNO FIRST_NAME           LAST_NAME                SALARY       COMM HIREDATE

---------- -------------------- -------------------- ---------- ---------- ---------

       103 Ram                  Hari                       2000         10 30-SEP-22

Lets say if we want find all employees whose first_name end with 'h' , note the use of $ symbol  Here is how you will do it :

SQL> select * from scott.emp where regexp_like(FIRST_NAME,'h$');

     EMPNO FIRST_NAME           LAST_NAME                SALARY       COMM HIREDATE

---------- -------------------- -------------------- ---------- ---------- ---------

       104 Rakesh               Sharma                     4000         10 30-SEP-22

Lets say if we want find all employees whose first_name starts with 'Ra' but it can be Ram or Rakesh so in the middle with paranthesis and pipe we use (m|k) and note it can be anything in the end so here we did not give any last alphabet condition so both Ram and Rakesh are printed. Here is how you will do it :

SQL> select * from scott.emp where regexp_like(FIRST_NAME,'^Ra(m|k)');

     EMPNO FIRST_NAME           LAST_NAME                SALARY       COMM HIREDATE

---------- -------------------- -------------------- ---------- ---------- ---------

       103 Ram                  Hari                       2000         10 30-SEP-22

       104 Rakesh               Sharma                     4000         10 30-SEP-22

How Indentation works in Python

 Lets say we want to write a python program to check whether a variable has a value 10 or not.

Code : 

var = 10

if (var == 10):

print(' A is 10')

Error :

File "<ipython-input-53-61659dc01be1>", line 3

    print(' A is 10')
    ^
IndentationError: expected an indented block

>> As we can see above we get the above error. This means the print statement is not as per expected indentation. Lets see if put it in the right way like below :

var = 10
if (var == 10):
  print(' A is 10')

In above code i try to shift/move the print statement a bit towards right side with a couple of spaces it could also be possible with tab and it works fine now.

 A is 10
In [ ]:

It prints the expected statement now as above we can see the actual cell is displayed .

AWK Essentials for DBAs and System Admins

• The awk command is a very powerful Linux tool and programming language that allows users to process and manipulate data and produce formatted reports. The tool supports various operations for advanced text processing and facilitates expressing complex data selections. In this tutorial, you will learn what the awk command does and how to use it.
• 
  

Scenario :

We need to print unique values from the 1st column. 

[oracle@rhel7 awk]$ awk -F, '{a[$1];}END{for (i in a)print i;}' a.txt

101

102

103

 

We have a file named a.txt

[oracle@rhel7 awk]$ cat a.txt

101,John,Smith

102,Karan,Dodwal

103,Oracle,Guru

# Here we want to check contents of the file

So just like cat, this awk command awk '{print;}' works :

 

[oracle@rhel7 awk]$  awk '{print;}'  a.txt

101,John,Smith

102,Karan,Dodwal

103,Oracle,Guru

 

[oracle@rhel7 awk]$ awk '{print $1}' a.txt

101,John,Smith

102,Karan,Dodwal

103,Oracle,Guru

Print 1st column with comma (,) as separator :

[oracle@rhel7 awk]$ awk -F "," '{print $1}' a.txt

101

102

103

Now lets print 3rd column :

[oracle@rhel7 awk]$ awk -F "," '{print $3}' a.txt

Smith

Dodwal

Guru

Print the lines which matches the pattern 

[oracle@rhel7 awk]$ awk '/Smith|Karan/' a.txt

101,John,Smith

102,Karan,Dodwal

Sum of all values in column 1 

[oracle@rhel7 awk]$ awk -F"," '{x+=$1}END{print x}' a.txt

306

## Printing the first row of a specific column outout from ps -ef | grep output

## First lets grep regular smon process

[oracle@rhel7 awk]$ ps -ef | grep smon

oracle     3742      1  0 16:07 ?        00:00:00 ora_smon_west

oracle     4999   3818  0 17:05 pts/2    00:00:00 grep --color=auto smon

# Now lets grep smon then second column and later first row that gets fetched from the second pipe

[oracle@rhel7 awk]$ ps -ef | grep smon | awk '{print $2}' | awk 'NR==1 {print $1}'

3742