I have a warehouse table with 16 tons of data in it. I have a few Integer columns in it. We have to cast these into BIGINT for every query we write, because the SUM is too large to fit in an INT.
We now have a new datamart under development. So we thought, why not change all these columns into BIGINT and we have less to worry for the new set of queries.
Since the data is already loaded, I figured I would use Management Studio and change the data type. But I first get a warning:
Saving Definition Changes to tables with large amounts of data could take a considerable amount of time. While changes are being saved, table data will not be accessible.
Then I get an error:
Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
How do I get around this?
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Answer
If one or more of those columns have no constraints against them (like a foreign key, index, default, rule, etc), you should be able to change each one quickly by doing
ALTER TABLE monster ALTER COLUMN MyIntCol1 bigint
Management Studio’s change SQL is rarely the most efficient and tends to favour temporary tables for anything modifying an existing column.