Re: someone working to add merge? - Mailing list pgsql-hackers

Tom Lane Wrote:

> Surely they require a unique constraint --- else the behavior
> isn't even well defined, is it?

From the mysql manual:

'REPLACE works exactly like INSERT, except that if an old record in the
table has the same value as a new record for a PRIMARY KEY or a UNIQUE
index, the old record is deleted before the new record is inserted. See
Section 13.2.4, "INSERT Syntax".'

... John