Change table/column/index names size in oracle 11g or 12c
Solution 1:
Database object names in 11g as well as in 12cR1 are limited to 30 bytes (in a single-byte character set it will be equivalent to 30 characters).
Can it be changed? No, you cannot make any changes to allow Oracle to use object names that are greater than 30 bytes.
The 30 bytes object names restriction has been lifted in second release of Oracle Database 12c ( 12cR2) and if the value of the COMPATIBLE initialization parameter is set to 12.2 or higher then object names' length can be up to 128 bytes.
Solution 2:
I know of no way to change the maximum size of fields to more than 30 characters in 11g.
I've seen nothing to suggest this is changing in 12c.