Alter a column length

Question

I need to alter the length of a column column_length in say more than 500 tables and the tables might have no of records ranging from 10 records to 3 or 4 million records.

1. The column may just be a normal column

CREATE TABLE test(column_length varchar(10))

2. The column might contain non-clustered index on it.

CREATE TABLE test(column_length varchar(10))
CREATE UNIQUE NONCLUSTERED INDEX column_length_ind ON test (column_length)

3. The column might contain PRIMARY KEY clustered index on it

CREATE TABLE test(column_length varchar(10))
ALTER TABLE test ADD PRIMARY KEY CLUSTERED INDEX ON column_length

4. The column might be a composite primary key

5. The column might have a foreign key reference

In short the column column_length might be anything.

All I need is to create scripts to alter the length of the column_length from varchar(10) to varchar(50). Should I drop the indexes before altering and then recreate them? What about the primary key and foreign key?

Through my research and testing I figured out that I can just alter the column's length without dropping the primary key or any indexes but have to drop and recreate the foreign key alone.

Is this assumption right?

Answer 1

Yes you should be able to just modify the columns. From my experience it is faster to leave the index and primary key in place.