Linearizability on Delta Lake table

[Torch3333]

Hi all,
Does Delta Lake table guarantee linearizability for the following operations on a single record:
- SELECT
- UPDATE and DELETE with condition (WHERE clauses)

If linearizability is not guaranteed, what consistency model does Delta Lake provide for these operations?

Thank you!

[Advika · Accepted solution]

Hello @Torch3333!

Delta Lake does not guarantee linearizability for single record operations. In Delta Lake, isolation levels ensure consistency guarantees in transactions. By default, SELECT operations follow snapshot isolation, ensuring that reads see a consistent table snapshot at the start of the transaction. UPDATE and DELETE operations use Write-Serializable isolation by default. For stricter consistency, setting delta.isolationLevel = 'Serializable' enforces transaction ordering.

For more details, refer to this documentation.