Hello, I noticed a behavior that was surprising to me, so I wanted to know if such behavior is expected.
I created a partial unique index on table "t", and a prepared statement in which a subexpression of the index's WHERE clause figures as a parameter. # CREATE TABLE t(i int); # CREATE UNIQUE INDEX ON t(i) WHERE i >= 2; # PREPARE u(int) AS INSERT INTO t VALUES(3) ON CONFLICT (i) WHERE i >= $1 DO NOTHING; After performing "EXPLAIN EXECUTE u(2)" 5 times and getting a valid query plan, the 6th execution of the same statement results in: # EXPLAIN EXECUTE u(2); ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification It seems that the attempt to create a generic execution plan fails because inference is impossible without a concrete value. The documentation for "PREPARE" talks about prepared statements being "semantically *almost* equivalent", so I guess some change in statement meaning is allowed (although in this case I'd say that the statement loses meaning after 5th execution, because it becomes invalid). Regards, Bojan
