> > There is no way to mimic IF NOT EXISTS on UPDATE and it's not a bug. INSERT > > and UPDATE are not totally orthogonal > in CQL and you should use INSERT for actual insertion and UPDATE for updates > (granted, the database will not reject > our query if you break this rule but it's nonetheless the way it's intended > to be used). > > OK.. (and not trying to be difficult here). We can’t have it both ways. One > of these use cases is a bug… > > You’re essentially saying “don’t do that, but yeah, you can do it.. “ > > Either UPDATE should support IF NOT EXISTS or UPDATE should not perform > INSERTs. >
UPDATE performs like INSERT in the meaning of an UPSERT - means: INSERT allows to write the same primary key again and UPDATE allows to write data to a non-existing primary key (effectively inserting data). (That’s what NoSQL databases do.) Take that as an advantage / feature not present on other DBs. "UPDATE … IF EXISTS“ and "INSERT … IF NOT EXISTS“ are *expensive* operations (require serial-consistency/LWT which requires some more network roundtrips). "IF [NOT] EXISTS“ is basically some kind of "convenience“. And please take into account that UPDATE also has "IF column = value“ condition (using LWT).
