> "every statement is atomic" Statement-level atomicity doesn't mean that you cannot get race conditions like the one that I described - it just means that the

> "every statement is atomic" Statement-level atomicity doesn't mean that you cannot get race conditions like the one that I described - it just means that the statement succeeds or fails as a whole. It's quite clear that you can get those race conditions in both Oracle and SQL Server's MERGE (same with the new Postgres implementation). Last I checked neither SQL Server nor Oracle address the fact that MERGE pretty much doesn't do what many of its users imagine it can do. (There is a narrow theoretical sense in which it does meet expectations provided serializable isolation level is used, but in practice that isn't worth much to users.) > anyway my experience has been that adding the lock hints "fixes" the problem with pk violations during concurrent upserts and it seemed to be commonly known and widely used afaict That's not my impression: https://www.mssqltips.com/sqlservertip/3074/use-caution-with-sql-servers-merge-statement/ https://www.mssqltips.com/sqlservertip/3074/use-caution-with...