Re: CHECK Constraint Deferrable - Mailing list pgsql-hackers

On Thu, 7 Sept 2023 at 17:26, Himanshu Upadhyaya
<upadhyaya.himanshu@gmail.com> wrote:
>
> Attached is v2 of the patch, rebased against the latest HEAD.

Thanks for working on this, few comments:
1) "CREATE TABLE check_constr_tbl (i int CHECK(i<>0) DEFERRABLE, t
text)" is crashing in windows, the same was noticed in CFBot too:
2023-09-11 08:11:36.585 UTC [58563][client backend]
[pg_regress/constraints][13/880:0] LOG:  statement: CREATE TABLE
check_constr_tbl (i int CHECK(i<>0) DEFERRABLE, t text);
2023-09-11 08:11:36.586 UTC [58560][client backend]
[pg_regress/inherit][15/391:0] LOG:  statement: drop table c1;
../src/backend/commands/trigger.c:220:26: runtime error: member access
within null pointer of type 'struct CreateTrigStmt'
==58563==Using libbacktrace symbolizer.

The details of CFBot failure can be seen at [1]

2) Alter of check constraint deferrable is not handled, is this intentional?
CREATE TABLE check_constr_tbl (i int CHECK(i<>0) DEFERRABLE, t text);
postgres=# alter table check_constr_tbl alter constraint
check_constr_tbl_i_check not deferrable;
ERROR:  constraint "check_constr_tbl_i_check" of relation
"check_constr_tbl" is not a foreign key constraint

3) Should we handle this scenario for domains too:
CREATE DOMAIN c1_check AS INT CHECK(VALUE > 10);
create table test(c1 c1_check);
alter domain c1_check ADD check (VALUE > 20) DEFERRABLE INITIALLY DEFERRED;

begin;
-- should this be deffered
insert into test values(19);
ERROR:  value for domain c1_check violates check constraint "c1_check_check1"

4) There is one warning:
heap.c: In function ‘StoreRelCheck’:
heap.c:2178:24: warning: implicit declaration of function
‘CreateTrigger’ [-Wimplicit-function-declaration]
 2178 |                 (void) CreateTrigger(trigger, NULL,
RelationGetRelid(rel),
      |   

                    ^~~~~~~~~~~~~

5) This should be added to typedefs.list file:
+typedef enum checkConstraintRecheck
+{
+       CHECK_RECHECK_DISABLED,         /* Recheck of CHECK constraint
is disabled, so
+                                                                *
DEFERRED CHECK constraint will be
+                                                                *
considered as non-deferrable check
+                                                                *
constraint.  */
+       CHECK_RECHECK_ENABLED,          /* Recheck of CHECK constraint
is enabled, so
+                                                                *
CHECK constraint will be validated but
+                                                                *
error will not be reported for deferred
+                                                                *
CHECK constraint. */
+       CHECK_RECHECK_EXISTING          /* Recheck of existing violated CHECK
+                                                                *
constraint, indicates that this is a
+                                                                *
deferred recheck of a row that was reported
+                                                                * as
a potential violation of CHECK
+                                                                * CONSTRAINT */
+}                      checkConstraintRecheck;