I want to change data type of a column of my table in SQL Server 2019. My table has 50,000,000 row and it's very important. I want to do this operation online and also handle maxdop to avoid CPU over usage. I wrote this query but I got syntax error:

Alter table Customers
alter column FirstName char(16) not null
with (online = on, maxdop = 4)

1 Answer 1


Per the Microsoft Docs, SQL Server 2019 ALTER TABLE ... ALTER COLUMN syntax does not support the MAXDOP = x option.

MAXDOP = x is only supported for single partition rebuilds and constraint operations.


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