The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/13/sql-createtable.html Description:
According to the docs: A constraint that is not deferrable will be checked immediately after every command. But this is the behavior I observe on PG 13.3: create table t (n int primary key); insert into t values (1), (2), (3); update t set n = n + 1; ERROR: 23505: duplicate key value violates unique constraint "t_pkey" DETAIL: Key (n)=(2) already exists. If the constraint was checked *after* the command it should work. It appears it is checked before the command has finished. In contrast a DEFERRABLE INITIALLY IMMEDIATE constraint which is documented as "If the constraint is INITIALLY IMMEDIATE, it is checked after each statement." behaves as expected. create table t (n int primary key deferrable initially immediate); insert into t values (1), (2), (3); update t set n = n + 1; --> UPDATE 3
