@Krishna Kommineni ,
MERGE command allows you to perform “upserts”, which are a mix of an UPDATE and an INSERT
To understand upserts, imagine that you have an existing table (a.k.a. a target table), and a source table that contains a mix of new records and updates to existing records. Here’s how an upsert works:
- When a record from the source table matches a preexisting record in the target table, Delta Lake updates the record.
- When there is no such match, Delta Lake inserts the new record.
Example code-
MERGE INTO events
USING updates
ON events.eventId = updates.eventId
WHEN MATCHED THEN UPDATE
SET events.data = updates.data
WHEN NOT MATCHED THEN
INSERT (date, eventId, data) VALUES (date, eventId, data)
