Alter Table Distribution Key or Policy

The first important thing, we have to define Distribution key correctly which is a primary for distribution of data in Greenplum DB. Altering the distribution key or policy of a table involves changing how the data is distributed across the segments of the Greenplum cluster. This can impact query performance and parallelism, so it’s an important consideration.
Greenplum DB is a base on MPP Architecture where we have data equally distributes across the child segments/tables. Before creating a table, we have to analyze the distribution logic and define distribution keys where data
must be unique for equal distribution.

suggestion by my END:
Once we distribute data basis on defined distribution key, we should not alter the distribution key.Remember that changing the distribution key or policy of a table can be a time-consuming operation, especially for large tables, as it involves redistributing the data across the segments. So, it’s recommended to perform such operations during maintenance windows or when the system can tolerate the load. Additionally, it’s essential to consider the impact on existing queries and workload patterns before making such changes.
as You know redistribution requires on disk which can be resource intensive, but still I am sharing the steps to ALTER the distribution key.

SYNTAX:-
CREATE TABLE <new_table> (LIKE <your_table> INCLUDING ALL);
ALTER TABLE <new_table> SET DISTRIBUTED BY (new_distribution_column);

Example:-
CREATE TABLE empcp (LIKE emp INCLUDING ALL);
ALTER TABLE empcp SET DISTRIBUTED BY (new_distribution_column);