Re: CHECK Constraint Deferrable

2.
- if ((failed = ExecRelCheck(resultRelInfo, slot, estate)) != NULL)
+ if ((failed = ExecRelCheck(resultRelInfo, slot, estate,
checkConstraint, &recheckConstraints)) != NULL && !recheckConstraints)


Why recheckConstraints need to get as output from ExecRelCheck?  I
mean whether it will be rechecked or nor is already known by the
caller and

Whether the constraint failed or passed is known based on the return
value so why do you need to extra parameter here?

5.
+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;

I do not like the naming convention here, especially the words
RECHECK, DISABLE, and ENABLE. And also the name of the enum is a bit
off.  We can name it more like a unique constraint
YES, PARTIAL, EXISTING