On 09/30/2014 07:15 AM, Kevin Grittner wrote: > There are certainly other ways to do it, although they require more > work. As far as UPSERT goes, I agree that we should require such > an index, at least for the initial implementation and into the > foreseeable future. What I'm saying is that if we implement it > using the standard MERGE syntax, then if the features of MERGE are > extended it will continue to work even in the absence of such an > index. The index becomes a way of optimizing access rather than > defining what access is allowed. > > At the risk of pushing people away from this POV, I'll point out > that this is somewhat similar to what we do for unlogged bulk loads > -- if all the conditions for doing it the fast way are present, we > do it the fast way; otherwise it still works, but slower.
Except that switching between fast/slow bulk loads affects *only* the speed of loading, not the locking rules. Having a statement silently take a full table lock when we were expecting it to be concurrent (because, for example, the index got rebuilt and someone forgot the UNIQUE) violates POLA from my perspective. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
