Thread: Re: support virtual generated column not null constraint

There are two minor issues i want to discuss:
1. The way of caching constraint-checking expr for virtual generated not null 
The existing array for caching constraint-checking expr is

 /* array of constraint-checking expr states */
ExprState **ri_ConstraintExprs;

the proposed changes for virtual generated not null in patch

+  /* array of virtual generated not null constraint-checking expr states */
+  ExprState **ri_VirGeneratedConstraintExprs;
/*
Could you explain the rationale behind adding this new field instead of reusing ri_ConstraintExprs? The comment suggests it’s used specifically for not null constraint-checking, but could it be extended to handle other constraints in the future as well? I assume one benefit is that it separates the handling of normal constraints from virtual ones, but I'd like to appreciate more context on the decision.

2. The naming of variable gen_virtualnn.
Gen_virtualnn looks confusing at first glance. Checkconstr seems to be more straightforward. 

    /* And evaluate the check constraints for virtual generated column */
+  for (i = 0; i < bms_num_members(gen_virtual_cols); i++)
+  {
+  ExprState  *gen_virtualnn = resultRelInfo->ri_VirGeneratedConstraintExprs[i];
+
+  if (gen_virtualnn && !ExecCheck(gen_virtualnn, econtext))
+  return attnums[i];
+  }
+

  /* And evaluate the constraints */
for (i = 0; i < ncheck; i++)
{
ExprState  *checkconstr = resultRelInfo->ri_ConstraintExprs[i];

/*
* NOTE: SQL specifies that a NULL result from a constraint expression
* is not to be treated as a failure.  Therefore, use ExecCheck not
* ExecQual.
*/
if (checkconstr && !ExecCheck(checkconstr, econtext))
return check[i].ccname;
}

/* NULL result means no error */
return NULL;

Best regards,
Xuneng