BigQuery Storage API: Atomicity of an append/write operation

Question

As the title states, are BigQuery Storage Write Requests atomic? I know that the legacy streaming API may return a partial error, indicating that some rows were successfully written. However, I understand we may achieve exactly-once processing at stream level through the use of offsets. But it seems that these offsets are for each write request and not at row level. Thus I am wondering, does a write operation using the new Storage API, fully complete or fully fail?

Answer 1

Offsets are row based, not request based. If an append request contains three rows for example, the offset would advance by three when processed successfully.

A success for an append in the write API means all the rows in the request were committed. If the stream type supports it (eg not a default stream) then the append response will confirm the offset.

This differs from the legacy streaming API ( tabledata.insertAll ), which allows for partial failures. In this surface, a three row request could have a single successful row and 2 failures, or some other combination of successes/failures.