Postgres tries to avoid "gotchas" like this. If SQL Server fixes all the issues listed above by the time Postgres releases its first version of MERGE, but Postgres's version actually works the first time because they spent enough time up front addressing concurrency issues, then IMO Postgres will have made the right call.
(And yes, if Microsoft is unable to ever fix all these issues and Postgres never releases the feature, I would still stand by this statement. I want to be able to rely on every feature in my database).
http://www.mssqltips.com/sqlservertip/3074/use-caution-with-...
Postgres tries to avoid "gotchas" like this. If SQL Server fixes all the issues listed above by the time Postgres releases its first version of MERGE, but Postgres's version actually works the first time because they spent enough time up front addressing concurrency issues, then IMO Postgres will have made the right call.
(And yes, if Microsoft is unable to ever fix all these issues and Postgres never releases the feature, I would still stand by this statement. I want to be able to rely on every feature in my database).