Code review for check-domain-constraints-in-COPY patch. Do correct thing

when default expression for a domain is being used.  Avoid repetitive
catalog lookups.

src/backend/commands/copy.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.174 2002/09/20 15:43:03 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.175 2002/09/20 16:56:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -43,6 +43,7 @@
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
 
+
 #define ISOCTAL(c) (((c) >= '0') && ((c) <= '7'))
 #define OCTVALUE(c) ((c) - '0')
 
@@ -746,8 +747,9 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
 				num_defaults;
 	FmgrInfo   *in_functions;
 	Oid		   *elements;
-	bool	   *isDomain;
+	Node	  **constraintexprs;
-	bool		hasDomain = false;
+	Const	  **constraintconsts;
+	bool		hasConstraints = false;
 	int			i;
 	List	   *cur;
 	Oid			in_func_oid;
@@ -792,15 +794,18 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
 	ExecSetSlotDescriptor(slot, tupDesc, false);
 
 	/*
-	 * pick up the input function and default expression (if any) for each
+	 * Pick up the required catalog information for each attribute in the
-	 * attribute in the relation.  (We don't actually use the input
+	 * relation, including the input function, the element type (to pass
-	 * function if it's a binary copy.)
+	 * to the input function), and info about defaults and constraints.
+	 * (We don't actually use the input function if it's a binary copy.)
 	 */
-	defmap = (int *) palloc(sizeof(int) * num_phys_attrs);
-	defexprs = (Node **) palloc(sizeof(Node *) * num_phys_attrs);
 	in_functions = (FmgrInfo *) palloc(num_phys_attrs * sizeof(FmgrInfo));
 	elements = (Oid *) palloc(num_phys_attrs * sizeof(Oid));
-	isDomain = (bool *) palloc(num_phys_attrs * sizeof(bool));
+	defmap = (int *) palloc(num_phys_attrs * sizeof(int));
+	defexprs = (Node **) palloc(num_phys_attrs * sizeof(Node *));
+	constraintexprs = (Node **) palloc(num_phys_attrs * sizeof(Node *));
+	constraintconsts = (Const **) palloc(num_phys_attrs * sizeof(Const *));
+	MemSet(constraintexprs, 0, num_phys_attrs * sizeof(Node *));
 
 	for (i = 0; i < num_phys_attrs; i++)
 	{
@@ -808,20 +813,12 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
 		if (attr[i]->attisdropped)
 			continue;
 
-		/* Test for the base type */
-		if (getBaseType(attr[i]->atttypid) != attr[i]->atttypid)
-		{
-			hasDomain = true;
-			isDomain[i] = true;
-		}
-		else
-			isDomain[i] = false;
-
 		/* Fetch the input function */
 		in_func_oid = (Oid) GetInputFunction(attr[i]->atttypid);
 		fmgr_info(in_func_oid, &in_functions[i]);
 		elements[i] = GetTypeElement(attr[i]->atttypid);
 
+		/* Get default info if needed */
 		if (intMember(i + 1, attnumlist))
 		{
 			/* attribute is to be copied */
@@ -839,6 +836,45 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
 				num_defaults++;
 			}
 		}
+
+		/* If it's a domain type, get info on domain constraints */
+		if (get_typtype(attr[i]->atttypid) == 'd')
+		{
+			Const	   *con;
+			Node	   *node;
+
+			/*
+			 * Easiest way to do this is to use parse_coerce.c to set up
+			 * an expression that checks the constraints.  (At present,
+			 * the expression might contain a length-coercion-function call
+			 * and/or ConstraintTest nodes.)  The bottom of the expression
+			 * is a Const node that we fill in with the actual datum during
+			 * the data input loop.
+			 *
+			 * XXX to prevent premature constant folding in parse_coerce,
+			 * pass in a NULL constant to start with.  See the comments in
+			 * coerce_type; this should be changed someday to use some sort
+			 * of Param node instead of a Const.
+			 */
+			con = makeConst(attr[i]->atttypid,
+							attr[i]->attlen,
+							(Datum) 0,
+							true,		 /* is null */
+							attr[i]->attbyval,
+							false,		/* not a set */
+							false);		/* not coerced */
+
+			node = coerce_type_constraints((Node *) con, attr[i]->atttypid,
+										   COERCE_IMPLICIT_CAST);
+
+			/* check whether any constraints actually found */
+			if (node != (Node *) con)
+			{
+				constraintexprs[i] = node;
+				constraintconsts[i] = con;
+				hasConstraints = true;
+			}
+		}
 	}
 
 	if (!binary)
@@ -1090,52 +1126,6 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
 			}
 		}
 
-		/* Deal with domains */
-		if (hasDomain)
-		{
-			ParseState *pstate;
-			pstate = make_parsestate(NULL);
-
-			foreach(cur, attnumlist)
-			{
-				int			attnum = lfirsti(cur);
-				int			m = attnum - 1;
-
-				Const	   *con;
-				Node	   *node;
-				bool	   isNull = (nulls[m] == 'n');
-
-				/* This is not a domain, so lets skip it */
-				if (!isDomain[m])
-					continue;
-
-				/*
-				 * This is a domain.  As such, we must process it's input
-				 * function and coerce_type_constraints.  The simplest way
-				 * of doing that is to allow coerce_type to accomplish its
-				 * job from an unknown constant
-				 */
-
-				/* Create a constant */
-				con = makeConst(attr[m]->atttypid,
-								attr[m]->attlen,
-								values[m],
-								isNull,
-								attr[m]->attbyval,
-								false,		/* not a set */
-								false);		/* not coerced */
-
-				/* Process constraints */
-				node = coerce_type_constraints((Node *) con, attr[m]->atttypid,
-												COERCE_IMPLICIT_CAST);
-
-				values[m] = ExecEvalExpr(node, econtext,
-										 &isNull, NULL);
-
-				nulls[m] = isNull ? 'n' : ' ';
-			}
-		}
-
 		/*
 		 * Now compute and insert any defaults available for the columns
 		 * not provided by the input data.	Anything not processed here or
@@ -1151,6 +1141,36 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
 				nulls[defmap[i]] = ' ';
 		}
 
+		/*
+		 * Next apply any domain constraints
+		 */
+		if (hasConstraints)
+		{
+			for (i = 0; i < num_phys_attrs; i++)
+			{
+				Node	   *node = constraintexprs[i];
+				Const	   *con;
+				bool		isnull;
+
+				if (node == NULL)
+					continue;	/* no constraint for this attr */
+
+				/* Insert current row's value into the Const node */
+				con = constraintconsts[i];
+				con->constvalue = values[i];
+				con->constisnull = (nulls[i] == 'n');
+
+				/*
+				 * Execute the constraint expression.  Allow the expression
+				 * to replace the value (consider e.g. a timestamp precision
+				 * restriction).
+				 */
+				values[i] = ExecEvalExpr(node, econtext,
+										 &isnull, NULL);
+				nulls[i] = isnull ? 'n' : ' ';
+			}
+		}
+
 		/*
 		 * And now we can form the input tuple.
 		 */