Check out the discussion in the video TSQL: Altering Column To NOT NULL Causes Log Growth Spike. In this situation, we see that a change needs to made to a column to set a default to NOT NULL from NULL. This may seem like an innocent operation, but we see this impacts the log (notice the before and after of this setting and keep in mind this limited test environment). As we dig through the change, we see many row modifications that log - exactly what we want, but what we must have ready if we make this change.
Some discussions and questions we see in the video:
- What was the situation with the original column?
- What did we want to accomplish?
- What analysis would we want to do before we want to make any updates or changes?
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Any possible issue from this is very easy to overlook, as a development environment may completely differ from a production environment. Size may be a big difference. This means that any test we do in development has a small impact, but in production, it has a large impact.