Support delete record with upsert table #10452
Description
Context
Upsert feature allows users to update existing records in Pinot. Deletes of existing records, however, are currently not supported.
Delete can be treated as a special kind of update operation and handled in Pinot's realtime engine. This will open up support for ingesting Change Data Capture (CDC) data like Debezium where the changes from a source (typically, transactional) will also contain a DELETE event.
The challenge here would be to handle out of order events correctly in the presence of deletes.