PostgreSQL 9.5 Does UPSERT Right (thenewstack.io)

joabj writes: For years, PostgreSQL users would ask when their favorite open source database system would get the UPSERT operator, which can either insert an entry or update it if a previous version already existed. Other RDMS have long offered this feature. Bruce Momjian, one of the chief contributors to PostgreSQL, admits to being embarrassed that it wasn't supported. Well, PostgreSQL 9.5, now generally available, finally offers a version of UPSERT and users may be glad the dev team took their time with it. Implementations of UPSERT on other database systems were "handled very badly," sometimes leading to unexpected error messages Momjian said. Turns out it is very difficult to implement on multi-user systems. "What is nice about our implementation is that it never generates an unexpected error. You can have multiple people doing this, and there is very little performance impact," Momjian said. Because it can work on multiple tables at once, it can even be used to merge one table into another.

Comments

Thanks a lot PostgreSQL devels

[hrumph]

This is great. I've been using PosgreSQL for a while now. It's one of those pieces of software that just does what it's told and doesn't let you down. While I'm saying this there are credible rumours to the effect that the Oracle merge operation is broken. Read the comments to the most upvoted answer at this stack exchange question. The final comment is:
Not reliably. I ended up with retry loops in the client code. :( – Randy Magruder Aug 27 '15 at 16:05
This makes me think that Bruce Momijan may have been thinking about Oracle's implementation of merge when he said that other implementations were handled very badly.