Replace Column names and datatype in Hive

Question

Hi. Can someone tell me how I can replace the name and datatype of a column in Hive table? I have some data in that column of datatype INT and want to change the name of this column, and datatype to STRING. So if I replace the name, will the data still exist or will it be erased?

Answer 1

You can replace the column name and the datatype using the ALTER command. Refer to the command below:

hive> ALTER TABLE <tablename> REPLACE COLUMNS (<old column name> INT, <new column name> STRING);

This command will only change the schema of the table i.e., it will change the column name and the datatype but will not affect the data stored in the column. 

Comments

Replace columns removes all existing columns and add the ones mentioned. Better option is using 'Change'.

hive> ALTER TABLE <tablename> CHANGE <old column name>, <new column name> STRING;