What to do when ETL has an error ORA-00972?

Oracle prohibited identifiers (names) of tables, fields, indexes if its contain more than 30 characters. 
This error indicates an identifier exceeds 30 characters,Especially if the name of the table is
close to 30 characters (29 or 30). If this error occurs during ETL please rename the table name 
(or Renames the fields are too large) to have at most 25 characters.