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

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.