-----Original Message----- From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general-owner@xxxxxxxxxxxxxx] On Behalf Of John R Pierce Sent: Wednesday, July 23, 2014 1:32 PM To: pgsql-general@xxxxxxxxxxxxxx Subject: Re: [GENERAL] Why is unique constraint needed for upsert? On 7/23/2014 10:21 AM, Seamus Abshere wrote: > hi all, > > Upsert is usually defined [1] in reference to a violating a unique key: > >> Insert, if unique constraint violation then update; or update, if not >> found then insert. > > Is this theoretically preferable to just looking for a row that > matches certain criteria, updating it if found or inserting otherwise? what happens when two connections do this more or less concurrently, in transactions? -- john r pierce 37N 122W somewhere on the middle of the left coast Well, that's exactly why OP prefers Mongo, which doesn't care about such "small" things as ACID. Regards, Igor Neyman
