Decrease time needed to CREATE INDEX and FOREIGN KEY on new table column which has all values NULL

[Denisa Cirstescu]

Hello all,

I am trying to add a new column to a really big table and to define an INDEX 
and a FOREIGN KEY on that new column using the following instructions:

ALTER TABLE Employee ADD COLUMN DepartmentId INTEGER;
CREATE INDEX IDX_Employee_DepartmentId ON Employee(DepartmentId);
ALTER TABLE Employee ADD CONSTRAINT FK_Employee_Department FOREIGN 
KEY(DepartmentId) REFERENCES Department(DepartmentId);

The table is huge and it takes a lot of time to add the INDEX and the FOREIGN 
KEY although all values are NULL.
Considering that the new DepartmentId column is NULL for all rows at this 
point, is there a way to make the INDEX and FOREIGN KEY creation run faster?

See below information about the size of the table and also the size of its 
associated Primary Key and Indexes:
              Employee                        339 GB
              Employee_PKEY              46 GB
              IDX_Employee_JobId     46 GB
              IDX_Employee_IsWFH   46 GB


Thank you,
Denisa Cîrstescu