MAXDATAFILES , DB_FILES parameters and ORA-00059

Problem Description
Whenever I try to create tablespace it fails with error message, ORA-00059.

SQL> create tablespace test_tbs;
create tablespace test_tbs
*
ERROR at line 1:
ORA-00059: maximum number of DB_FILES exceeded

Cause of The Problem
You have reached the limit of DB_FILES parameter. Before entering into solution part let's have an idea about DB_FILES and MAXDATAFILES parameter.

The DB_FILES parameter limits the maximum number of datafile can exist in oracle database. We can't change this parameter dynamically. We have to change it spfile by using ALTER SYSTEM .... SCOPE=SPFILE or in the pfile.

And the MAXDATAFILES parameter you can find with the CREATE DATABASE command or in CREATE CONTROLFILE command. It is also a limitation of maximum number of datafiles can be in the datafile. But starting from oracle 8 this hard limit parameter can be easily expanded up to DB_FILES parameter. So, if you attempt to add a new file whose number is greater than MAXDATAFILES, but less than or equal to DB_FILES, the MAXDATAFILES parameter of the control file will expand automatically to accommodate more files.

So, if you are after oracle 8i then we should just forget about MAXDATAFILES parameter. We should rather think about DB_FILES parameter.

Solution of The Problem
If you use pfile to startup the database then edit pfile and add/modify the DB_FILES parameter to a greater value so that it can accommodate higher number of datafiles. Then start the database using that pfile.

If you use spfile to startup the database then issue,

SQL> alter system set db_files=300 scope=spfile;
System altered.

Then start your database and either create tablespace or add datafile to an existing tablespace. Hopefully it will work.

SQL> conn / as sysdba
SQL> startup force
SQL> CREATE TABLESPACE or ALTER TABLESPACE command to add datafile.