upsertAll

Writes a batch of rows produced from one ack set, one page of server changes, or one tombstone sweep. The default calls upsert per row; override it to write the batch in a single database transaction. The engine reads rows before calling this method, so a transaction around these writes alone does not make its guards atomic with concurrent local edits. Adapters must also enforce conditional writes against the current local version when local editing can race sync persistence.