What is the fastest way to alter a table

I have sql server table with 70M rows.
I need to increase the field len of a single field.
Last time I did this it toke 5 hours.
What is the fastest way to run something like this.  I don't care about log files or having to revert. I don't have 5 hours to wait.

ALTER TABLE myTable            
ALTER COLUMN [Customer] nvarchar(150)

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Vitor MontalvãoMSSQL Senior EngineerCommented:
Are you adding the column during working hours?
If so, then create a job with the alter command and schedule it to run in non-working hours (during the night for example).
JElsterAuthor Commented:
Yes... Need to do immediate change.  Can't wait for off hours.
Vitor MontalvãoMSSQL Senior EngineerCommented:
This will run faster if no default value is set for that column and also if nobody access the table during the ALTER process.
Vitor MontalvãoMSSQL Senior EngineerCommented:
You may also drop all indexes on the table before running the ALTER command and recreate them after the new column be added.
Scott PletcherSenior DBACommented:
As long as you are lengthening the column, that command should return very quickly; just be sure to specify exactly the same NULL or NOT NULL as the column currently has:

ALTER TABLE myTable            
ALTER COLUMN [Customer] nvarchar(150) NULL --or NOT NULL, based on the current column definition

If it takes too long, it's likely SQL is simply waiting to get the required schema lock to make the change.

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Microsoft SQL Server

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