Resize an UNDO tablespace Oracle 10g

1.

sqlplus SYS AS SYSDBA

2.

SELECT file_name, tablespace_name, bytes/1024/1024 UNDO_SIZE_MB, SUM(bytes/1024/1024) OVER() TOTAL_UNDO_SIZE_MB FROM dba_data_files d WHERE EXISTS (SELECT 1 FROM v$parameter p WHERE LOWER (p.name)='undo_tablespace' AND p.value=d.tablespace_name);

3.
alter database datafile '/oracle/ora10g/ecms/syscom01.dbf' resize 4G;


Note: It is not recommended to grow any data files above 20 GB in size. If a tablespace needs to be grown over 20 GB a new datafile has to be added.

source  : https://www.ibm.com/docs/en/tnpm/1.4.4?topic=administration-resize-undo-tablespace

https://forums.oracle.com/ords/apexds/post/resize-datafile-5440

How to increase PROCESSES initialization parameter. ORA-00020 maximum number of processes exceeded..

 ORA-00020 maximum number of processes exceeded

Cause: All process state objects are in use.

Action: Increase the value of the PROCESSES initialization parameter.


ORA-00020 comes under "Oracle Database Server Messages". These messages are generated by the Oracle database server when running any Oracle program.



1.   Login as sysdba

   sqlplus / as sysdba

   

2. Check Current Setting of Parameters

   sql> show parameter sessions;

   sql> show parameter processes;

   sql> show parameter transactions;


3.   If you are planning to increase "PROCESSES" parameter you should also plan to increase "sessions and "transactions" parameters

   A basic formula for determining these parameter values is as follows:

   

      processes=x

      sessions=x*1.1+5

      transactions=sessions*1.1

      

4.   These paramters can't be modified in memory. You have to modify the spfile only (scope=spfile) and bounce the instance.

   sql> alter system set processes=500 scope=spfile;

   sql> alter system set sessions=555 scope=spfile;

   sql> alter system set transactions=610 scope=spfile;

   sql> shutdown abort
   sql> startup

#source : https://www.linkedin.com/pulse/how-increase-processes-initialization-parameter-ora-00020-jain