Databases · Senior · Question 71 of 75

Why should migrations be tested against a production-sized copy of the data?

1Small databases don't support migrations
✓Correct answer: Lock duration, table rewrites, index builds and backfills behave very differently on 1,000 rows than on 1 billion
3Migrations use different SQL syntax in production

Explanation

Measure duration and locks on realistic data, and use masked copies so personal data doesn't leak into staging.

Further reading

Test yourself

Take the Databases · Senior quiz: questions and options are shuffled, and you get a review of your mistakes at the end.