Oracle 12c নিউ ফিচার গাইড অনুযায়ী-
“The maximum size of the VARCHAR2, NVARCHAR2, and RAW data types has been increased from 4,000 to 32,767 bytes. Increasing the allotted size for these data types allows users to store more information in character data types before switching to large objects (LOBs). This is especially useful for brief textual data types and the capabilities to build indexes on these types of columns.”
(Oracle® Database New Features Guide 12c Release 1 (12.1) E17906-16 Page 1-13) Continue reading Extend varchar2 data type length 4K to 32K in 12c