pick from master #37069
add a new session variable: use_max_length_of_varchar_in_ctas
In CTAS (Create Table As Select), if CHAR/VARCHAR columns do not
originate from the source table, whether to set the length of such a
column to MAX, which is 65533. The default is true.
Problem:
when we create table with datatype varchar(), we regard it to be max length by default. But when we desc, it does not show
real length but show varchar()
Reason:
when we upgrade version from 2.0.1 to 2.0.2, we support new feature of creating varchar(), and it shows the same way with
ddl schema. So user would confuse of the length of varchar
Solved:
change the showing of varchar() to varchar(65533), which in compatible with hive
