Drop column in Impala

Question

I want to drop the whole column 'index' (column name and values) in Impala:

index	case_id	customer_id
1	A	xxx56

I used this code:

ALTER TABLE DBName.Tablename
DROP COLUMN index;

The result is like this:

case_id	customer_id
1	A

How can I solve this?

Answer 1

Dropping a column with ALTER TABLE mytab DROP COLUMN col will alter only metadata and underlying data remains intact. Which means you got the columns shifted although data is intact.

Only solution is to backup, drop and recreate the table.

create table DBName.Tablename_tmp as select case_id,    customer_id from DBName.Tablename; -- just backup table with new structure.
drop table DBName.Tablename;
create table DBName.Tablename as select * from DBName.Tablename_stg;