On 2014-09-29 15:08:36 -0700, Kevin Grittner wrote: > 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.
Wrong. You can't realistically implement the guarantees of UPSERT without a corresponding UNIQUE index. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
