Add a new partition in hive external table and update the existing partition to column of the table to non-partition column

Question

I have below existing table emp with partition column as as_of_date(current_date -1).

CREATE EXTERNAL TABLE IF NOT EXISTS emp(
  student_ID INT, 
  name STRING)
  partitioned by (as_of_date date)
  ROW FORMAT DELIMITED
  FIELDS TERMINATED BY ','
  STORED AS TEXTFILE
  LOCATION '/user/emp';

Below are the existing partition path

user/emp/as_of_date=2021-09-02
user/emp/as_of_date=2021-09-03
user/emp/as_of_date=2021-09-04

In emp table, I have to add new partition column as businessdate(current_date) and change partition column (as_of_date) to non-partition column.

Expected output should be as below.

describe table emp;
CREATE EXTERNAL TABLE IF NOT EXISTS emp(
student_ID INT, 
Name STRING, 
as_of_date date)
  partitioned by (businessdate date)
  ROW FORMAT DELIMITED
  FIELDS TERMINATED BY ','
  STORED AS TEXTFILE
  LOCATION '/user/emp';

After update, below will be hdfs path

user/emp/buinessdate=2021-09-03
user/emp/buinessdate=2021-09-04
user/emp/businessdate=2021-09-05

Expected output table:

|student_ID |name |as_of_date | business_date |
|--| --- | --- |----|
|1 | Sta |2021-09-02| 2021-09-03 |
|2 |Danny|2021-09-03| 2021-09-04 |
|3 |Elle |2021-09-04| 2021-09-05 |

Answer 1

Create new table, load data from old table, remove old table, rename new table.

--1 Create new table emp1

CREATE EXTERNAL TABLE emp1(
student_ID INT, 
Name STRING, 
as_of_date date)
  partitioned by (businessdate date)
  ROW FORMAT DELIMITED
  FIELDS TERMINATED BY ','
  STORED AS TEXTFILE
  LOCATION '/user/emp1';

--2 Load data into emp1 from the emp with new partition column calculated

--dynamic partition mode
SET hive.exec.dynamic.partition=true;
SET hive.exec.dynamic.partition.mode=nonstrict;

insert overwrite table emp1 partition (business_date)
select 
     student_ID, 
     Name, 
     as_of_date,
     date_add(as_of_date,1) as business_date
 from emp;

Now you can drop old (make it managed first to drop location as well) and rename new table if necessary.