Databases · Middle · Question 22 of 75

What does `INSERT ... ON CONFLICT (email) DO UPDATE` do?

1Inserts the row and ignores any errors
2Updates all rows with the same email
✓Correct answer: Inserts the row, or updates the existing row if the unique key already exists (an atomic upsert)

Explanation

It's safe under concurrency, unlike 'select, then insert or update'. DO NOTHING simply skips duplicates. The conflict target needs a unique index.

Further reading

PostgreSQL: INSERT (ON CONFLICT) ↗

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