Andres Freund <and...@2ndquadrant.com> wrote: > On 2014-09-29 14:57:45 -0700, Kevin Grittner wrote:
>> The initial implementation could restrict to these exact clauses >> and require that the boolean-expression used equality-quals on all >> columns of a unique index on only NOT NULL columns. > > That'll make it really hard to actually implement real MERGE. > > Because suddenly there's no way for the user to know whether he's > written a ON condition that can implement UPSERT like properties > (i.e. the *precise* column list of an index) or not. Well, unless we abandon transactional semantics for other MERGE statements, we should have a way that UPSERT logic continues to work if you don't match a suitable index; it will just be slower -- potentially a lot slower, but that's what indexes are for. I don't think we need a separate statement type for the one we "do well", because I don't think we should do the other one without proper transactional semantics. -- Kevin Grittner EDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
