From 3752e85bad45e98383ea1c9e7e7dbaf13f41da7e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 3 Feb 2003 21:15:45 +0000
Subject: [PATCH] Determine the set of constraints applied to a domain at
 executor startup, not in the parser; this allows ALTER DOMAIN to work
 correctly with domain constraint operations stored in rules.  Rod Taylor;
 code review by Tom Lane.

---
 src/backend/commands/copy.c            |  24 ++-
 src/backend/commands/typecmds.c        | 129 ++++++++++++++-
 src/backend/executor/execQual.c        |  82 +++++-----
 src/backend/nodes/copyfuncs.c          |  33 ++--
 src/backend/nodes/equalfuncs.c         |  28 ++--
 src/backend/nodes/outfuncs.c           |  25 ++-
 src/backend/nodes/readfuncs.c          |  33 ++--
 src/backend/optimizer/path/clausesel.c |  10 +-
 src/backend/optimizer/prep/preptlist.c |   9 +-
 src/backend/optimizer/util/clauses.c   |  21 ++-
 src/backend/parser/parse_coerce.c      | 212 ++++++++-----------------
 src/backend/parser/parse_expr.c        |  22 +--
 src/backend/utils/adt/ruleutils.c      |  46 ++++--
 src/backend/utils/cache/lsyscache.c    |  29 +++-
 src/include/catalog/catversion.h       |   4 +-
 src/include/commands/typecmds.h        |   4 +-
 src/include/nodes/execnodes.h          |  34 +++-
 src/include/nodes/nodes.h              |   9 +-
 src/include/nodes/primnodes.h          |  34 ++--
 src/include/parser/parse_coerce.h      |   6 +-
 src/include/utils/lsyscache.h          |   3 +-
 src/pl/plpgsql/src/pl_exec.c           |   5 +-
 src/test/regress/expected/domain.out   |  41 ++++-
 src/test/regress/sql/domain.sql        |  20 +++
 24 files changed, 524 insertions(+), 339 deletions(-)

diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 91386eeb2c..baaf57a70a 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.188 2003/01/10 22:03:27 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.189 2003/02/03 21:15:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -853,7 +853,7 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
 			}
 		}
 
-		/* If it's a domain type, get info on domain constraints */
+		/* If it's a domain type, set up to check domain constraints */
 		if (get_typtype(attr[i]->atttypid) == 'd')
 		{
 			Param	   *prm;
@@ -863,25 +863,23 @@ CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
 			 * 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
+			 * and/or CoerceToDomain nodes.)  The bottom of the expression
 			 * is a Param node so that we can fill in the actual datum during
 			 * the data input loop.
 			 */
 			prm = makeNode(Param);
 			prm->paramkind = PARAM_EXEC;
 			prm->paramid = 0;
-			prm->paramtype = attr[i]->atttypid;
+			prm->paramtype = getBaseType(attr[i]->atttypid);
 
-			node = coerce_type_constraints((Node *) prm, attr[i]->atttypid,
-										   COERCE_IMPLICIT_CAST);
+			node = coerce_to_domain((Node *) prm,
+									prm->paramtype,
+									attr[i]->atttypid,
+									COERCE_IMPLICIT_CAST);
 
-			/* check whether any constraints actually found */
-			if (node != (Node *) prm)
-			{
-				constraintexprs[i] = ExecPrepareExpr((Expr *) node,
-													 estate);
-				hasConstraints = true;
-			}
+			constraintexprs[i] = ExecPrepareExpr((Expr *) node,
+												 estate);
+			hasConstraints = true;
 		}
 	}
 
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
index 379e4bb9b4..ad95460537 100644
--- a/src/backend/commands/typecmds.c
+++ b/src/backend/commands/typecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/typecmds.c,v 1.29 2003/01/08 22:06:23 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/typecmds.c,v 1.30 2003/02/03 21:15:43 tgl Exp $
  *
  * DESCRIPTION
  *	  The "DefineFoo" routines take the parse tree and pick out the
@@ -46,8 +46,10 @@
 #include "commands/typecmds.h"
 #include "executor/executor.h"
 #include "miscadmin.h"
+#include "nodes/execnodes.h"
 #include "nodes/nodes.h"
 #include "optimizer/clauses.h"
+#include "optimizer/planmain.h"
 #include "optimizer/var.h"
 #include "parser/parse_coerce.h"
 #include "parser/parse_expr.h"
@@ -1555,7 +1557,7 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid,
 	char	   *ccsrc;
 	char	   *ccbin;
 	ParseState *pstate;
-	ConstraintTestValue  *domVal;
+	CoerceToDomainValue  *domVal;
 
 	/*
 	 * Assign or validate constraint name
@@ -1582,13 +1584,13 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid,
 	pstate = make_parsestate(NULL);
 
 	/*
-	 * Set up a ConstraintTestValue to represent the occurrence of VALUE
+	 * Set up a CoerceToDomainValue to represent the occurrence of VALUE
 	 * in the expression.  Note that it will appear to have the type of the
 	 * base type, not the domain.  This seems correct since within the
 	 * check expression, we should not assume the input value can be considered
 	 * a member of the domain.
 	 */
-	domVal = makeNode(ConstraintTestValue);
+	domVal = makeNode(CoerceToDomainValue);
 	domVal->typeId = baseTypeOid;
 	domVal->typeMod = typMod;
 
@@ -1669,6 +1671,125 @@ domainAddConstraint(Oid domainOid, Oid domainNamespace, Oid baseTypeOid,
 	return ccbin;
 }
 
+/*
+ * GetDomainConstraints - get a list of the current constraints of domain
+ *
+ * Returns a possibly-empty list of DomainConstraintState nodes.
+ *
+ * This is called by the executor during plan startup for a CoerceToDomain
+ * expression node.  The given constraints will be checked for each value
+ * passed through the node.
+ */
+List *
+GetDomainConstraints(Oid typeOid)
+{
+	List	   *result = NIL;
+	bool		notNull = false;
+	Relation	conRel;
+
+	conRel = heap_openr(ConstraintRelationName, AccessShareLock);
+
+	for (;;)
+	{
+		HeapTuple	tup;
+		HeapTuple	conTup;
+		Form_pg_type typTup;
+		ScanKeyData key[1];
+		SysScanDesc scan;
+		
+		tup = SearchSysCache(TYPEOID,
+							 ObjectIdGetDatum(typeOid),
+							 0, 0, 0);
+		if (!HeapTupleIsValid(tup))
+			elog(ERROR, "GetDomainConstraints: failed to lookup type %u",
+				 typeOid);
+		typTup = (Form_pg_type) GETSTRUCT(tup);
+
+		/* Test for NOT NULL Constraint */
+		if (typTup->typnotnull)
+			notNull = true;
+
+		/* Look for CHECK Constraints on this domain */
+		ScanKeyEntryInitialize(&key[0], 0x0,
+							   Anum_pg_constraint_contypid, F_OIDEQ,
+							   ObjectIdGetDatum(typeOid));
+
+		scan = systable_beginscan(conRel, ConstraintTypidIndex, true,
+								  SnapshotNow, 1, key);
+
+		while (HeapTupleIsValid(conTup = systable_getnext(scan)))
+		{
+			Form_pg_constraint	c = (Form_pg_constraint) GETSTRUCT(conTup);
+			Datum	val;
+			bool	isNull;
+			Expr   *check_expr;
+			DomainConstraintState *r;
+
+			/* Ignore non-CHECK constraints (presently, shouldn't be any) */
+			if (c->contype != CONSTRAINT_CHECK)
+				continue;
+
+			/* Not expecting conbin to be NULL, but we'll test for it anyway */
+			val = fastgetattr(conTup, Anum_pg_constraint_conbin,
+							  conRel->rd_att, &isNull);
+			if (isNull)
+				elog(ERROR, "GetDomainConstraints: domain %s constraint %s has NULL conbin",
+					 NameStr(typTup->typname), NameStr(c->conname));
+
+			check_expr = (Expr *)
+				stringToNode(DatumGetCString(DirectFunctionCall1(textout,
+																 val)));
+
+			/* ExecInitExpr assumes we already fixed opfuncids */
+			fix_opfuncids((Node *) check_expr);
+
+			r = makeNode(DomainConstraintState);
+			r->constrainttype = DOM_CONSTRAINT_CHECK;
+			r->name = pstrdup(NameStr(c->conname));
+			r->check_expr = ExecInitExpr(check_expr, NULL);
+
+			/*
+			 * use lcons() here because constraints of lower domains should
+			 * be applied earlier.
+			 */
+			result = lcons(r, result);
+		}
+
+		systable_endscan(scan);
+
+		if (typTup->typtype != 'd')
+		{
+			/* Not a domain, so done */
+			ReleaseSysCache(tup);
+			break;
+		}
+
+		/* else loop to next domain in stack */
+		typeOid = typTup->typbasetype;
+		ReleaseSysCache(tup);
+	}
+
+	heap_close(conRel, AccessShareLock);
+
+	/*
+	 * Only need to add one NOT NULL check regardless of how many domains
+	 * in the stack request it.
+	 */
+	if (notNull)
+	{
+		DomainConstraintState *r = makeNode(DomainConstraintState);
+
+		r->constrainttype = DOM_CONSTRAINT_NOTNULL;
+		r->name = pstrdup("NOT NULL");
+		r->check_expr = NULL;
+
+		/* lcons to apply the nullness check FIRST */
+		result = lcons(r, result);
+	}
+
+	return result;
+}
+
 /*
  * ALTER DOMAIN .. OWNER TO
  *
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index c13e1e1e4d..a2583fcc4c 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.123 2003/01/12 04:03:34 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.124 2003/02/03 21:15:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -36,6 +36,7 @@
 
 #include "access/heapam.h"
 #include "catalog/pg_type.h"
+#include "commands/typecmds.h"
 #include "executor/execdebug.h"
 #include "executor/functions.h"
 #include "executor/nodeSubplan.h"
@@ -80,10 +81,10 @@ static Datum ExecEvalNullTest(GenericExprState *nstate,
 static Datum ExecEvalBooleanTest(GenericExprState *bstate,
 								 ExprContext *econtext,
 								 bool *isNull, ExprDoneCond *isDone);
-static Datum ExecEvalConstraintTest(ConstraintTestState *cstate,
+static Datum ExecEvalCoerceToDomain(CoerceToDomainState *cstate,
 					   ExprContext *econtext,
 					   bool *isNull, ExprDoneCond *isDone);
-static Datum ExecEvalConstraintTestValue(ConstraintTestValue *conVal,
+static Datum ExecEvalCoerceToDomainValue(CoerceToDomainValue *conVal,
 					   ExprContext *econtext, bool *isNull);
 static Datum ExecEvalFieldSelect(GenericExprState *fstate,
 								 ExprContext *econtext,
@@ -1559,32 +1560,37 @@ ExecEvalBooleanTest(GenericExprState *bstate,
 }
 
 /*
- * ExecEvalConstraintTest
+ * ExecEvalCoerceToDomain
  *
- * Test the constraint against the data provided.  If the data fits
- * within the constraint specifications, pass it through (return the
+ * Test the provided data against the domain constraint(s).  If the data
+ * passes the constraint specifications, pass it through (return the
  * datum) otherwise throw an error.
  */
 static Datum
-ExecEvalConstraintTest(ConstraintTestState *cstate, ExprContext *econtext,
+ExecEvalCoerceToDomain(CoerceToDomainState *cstate, ExprContext *econtext,
 					   bool *isNull, ExprDoneCond *isDone)
 {
-	ConstraintTest *constraint = (ConstraintTest *) cstate->xprstate.expr;
+	CoerceToDomain *ctest = (CoerceToDomain *) cstate->xprstate.expr;
 	Datum		result;
+	List	   *l;
 
 	result = ExecEvalExpr(cstate->arg, econtext, isNull, isDone);
 
 	if (isDone && *isDone == ExprEndResult)
 		return result;			/* nothing to check */
 
-	switch (constraint->testtype)
+	foreach(l, cstate->constraints)
 	{
-		case CONSTR_TEST_NOTNULL:
-			if (*isNull)
-				elog(ERROR, "Domain %s does not allow NULL values",
-					 constraint->domname);
-			break;
-		case CONSTR_TEST_CHECK:
+		DomainConstraintState *con = (DomainConstraintState *) lfirst(l);
+
+		switch (con->constrainttype)
+		{
+			case DOM_CONSTRAINT_NOTNULL:
+				if (*isNull)
+					elog(ERROR, "Domain %s does not allow NULL values",
+						 format_type_be(ctest->resulttype));
+				break;
+			case DOM_CONSTRAINT_CHECK:
 			{
 				Datum	conResult;
 				bool	conIsNull;
@@ -1592,7 +1598,7 @@ ExecEvalConstraintTest(ConstraintTestState *cstate, ExprContext *econtext,
 				bool	save_isNull;
 
 				/*
-				 * Set up value to be returned by ConstraintTestValue nodes.
+				 * Set up value to be returned by CoerceToDomainValue nodes.
 				 * We must save and restore prior setting of econtext's
 				 * domainValue fields, in case this node is itself within
 				 * a check expression for another domain.
@@ -1603,35 +1609,37 @@ ExecEvalConstraintTest(ConstraintTestState *cstate, ExprContext *econtext,
 				econtext->domainValue_datum = result;
 				econtext->domainValue_isNull = *isNull;
 
-				conResult = ExecEvalExpr(cstate->check_expr,
+				conResult = ExecEvalExpr(con->check_expr,
 										 econtext, &conIsNull, NULL);
 
 				if (!conIsNull &&
 					!DatumGetBool(conResult))
-					elog(ERROR, "ExecEvalConstraintTest: Domain %s constraint %s failed",
-						 constraint->domname, constraint->name);
+					elog(ERROR, "ExecEvalCoerceToDomain: Domain %s constraint %s failed",
+						 format_type_be(ctest->resulttype), con->name);
 
 				econtext->domainValue_datum = save_datum;
 				econtext->domainValue_isNull = save_isNull;
+
+				break;
 			}
-			break;
-		default:
-			elog(ERROR, "ExecEvalConstraintTest: Constraint type unknown");
-			break;
+			default:
+				elog(ERROR, "ExecEvalCoerceToDomain: Constraint type unknown");
+				break;
+		}
 	}
 
-	/* If all has gone well (constraint did not fail) return the datum */
+	/* If all has gone well (constraints did not fail) return the datum */
 	return result;
 }
 
 /*
- * ExecEvalConstraintTestValue
+ * ExecEvalCoerceToDomainValue
  *
- * Return the value stored by constraintTest.
+ * Return the value stored by CoerceToDomain.
  */
 static Datum
-ExecEvalConstraintTestValue(ConstraintTestValue *conVal, ExprContext *econtext,
-							bool *isNull)
+ExecEvalCoerceToDomainValue(CoerceToDomainValue *conVal,
+							ExprContext *econtext, bool *isNull)
 {
 	*isNull = econtext->domainValue_isNull;
 	return econtext->domainValue_datum;
@@ -1830,14 +1838,14 @@ ExecEvalExpr(ExprState *expression,
 										   isNull,
 										   isDone);
 			break;
-		case T_ConstraintTest:
-			retDatum = ExecEvalConstraintTest((ConstraintTestState *) expression,
+		case T_CoerceToDomain:
+			retDatum = ExecEvalCoerceToDomain((CoerceToDomainState *) expression,
 											  econtext,
 											  isNull,
 											  isDone);
 			break;
-		case T_ConstraintTestValue:
-			retDatum = ExecEvalConstraintTestValue((ConstraintTestValue *) expr,
+		case T_CoerceToDomainValue:
+			retDatum = ExecEvalCoerceToDomainValue((CoerceToDomainValue *) expr,
 												   econtext,
 												   isNull);
 			break;
@@ -1915,7 +1923,7 @@ ExecInitExpr(Expr *node, PlanState *parent)
 		case T_Var:
 		case T_Const:
 		case T_Param:
-		case T_ConstraintTestValue:
+		case T_CoerceToDomainValue:
 			/* No special setup needed for these node types */
 			state = (ExprState *) makeNode(ExprState);
 			break;
@@ -2092,13 +2100,13 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				state = (ExprState *) gstate;
 			}
 			break;
-		case T_ConstraintTest:
+		case T_CoerceToDomain:
 			{
-				ConstraintTest   *ctest = (ConstraintTest *) node;
-				ConstraintTestState *cstate = makeNode(ConstraintTestState);
+				CoerceToDomain   *ctest = (CoerceToDomain *) node;
+				CoerceToDomainState *cstate = makeNode(CoerceToDomainState);
 
 				cstate->arg = ExecInitExpr(ctest->arg, parent);
-				cstate->check_expr = ExecInitExpr(ctest->check_expr, parent);
+				cstate->constraints = GetDomainConstraints(ctest->resulttype);
 				state = (ExprState *) cstate;
 			}
 			break;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 667e4f30c2..8437ed82a5 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.238 2003/01/23 23:38:56 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.239 2003/02/03 21:15:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -933,29 +933,28 @@ _copyBooleanTest(BooleanTest *from)
 }
 
 /*
- * _copyConstraintTest
+ * _copyCoerceToDomain
  */
-static ConstraintTest *
-_copyConstraintTest(ConstraintTest *from)
+static CoerceToDomain *
+_copyCoerceToDomain(CoerceToDomain *from)
 {
-	ConstraintTest *newnode = makeNode(ConstraintTest);
+	CoerceToDomain *newnode = makeNode(CoerceToDomain);
 
 	COPY_NODE_FIELD(arg);
-	COPY_SCALAR_FIELD(testtype);
-	COPY_STRING_FIELD(name);
-	COPY_STRING_FIELD(domname);
-	COPY_NODE_FIELD(check_expr);
+	COPY_SCALAR_FIELD(resulttype);
+	COPY_SCALAR_FIELD(resulttypmod);
+	COPY_SCALAR_FIELD(coercionformat);
 
 	return newnode;
 }
 
 /*
- * _copyConstraintTestValue
+ * _copyCoerceToDomainValue
  */
-static ConstraintTestValue *
-_copyConstraintTestValue(ConstraintTestValue *from)
+static CoerceToDomainValue *
+_copyCoerceToDomainValue(CoerceToDomainValue *from)
 {
-	ConstraintTestValue *newnode = makeNode(ConstraintTestValue);
+	CoerceToDomainValue *newnode = makeNode(CoerceToDomainValue);
 
 	COPY_SCALAR_FIELD(typeId);
 	COPY_SCALAR_FIELD(typeMod);
@@ -2476,11 +2475,11 @@ copyObject(void *from)
 		case T_BooleanTest:
 			retval = _copyBooleanTest(from);
 			break;
-		case T_ConstraintTest:
-			retval = _copyConstraintTest(from);
+		case T_CoerceToDomain:
+			retval = _copyCoerceToDomain(from);
 			break;
-		case T_ConstraintTestValue:
-			retval = _copyConstraintTestValue(from);
+		case T_CoerceToDomainValue:
+			retval = _copyCoerceToDomainValue(from);
 			break;
 		case T_TargetEntry:
 			retval = _copyTargetEntry(from);
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 1982973696..7916ca0fca 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.182 2003/01/23 23:38:56 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.183 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -383,19 +383,25 @@ _equalBooleanTest(BooleanTest *a, BooleanTest *b)
 }
 
 static bool
-_equalConstraintTest(ConstraintTest *a, ConstraintTest *b)
+_equalCoerceToDomain(CoerceToDomain *a, CoerceToDomain *b)
 {
 	COMPARE_NODE_FIELD(arg);
-	COMPARE_SCALAR_FIELD(testtype);
-	COMPARE_STRING_FIELD(name);
-	COMPARE_STRING_FIELD(domname);
-	COMPARE_NODE_FIELD(check_expr);
+	COMPARE_SCALAR_FIELD(resulttype);
+	COMPARE_SCALAR_FIELD(resulttypmod);
+	/*
+	 * Special-case COERCE_DONTCARE, so that pathkeys can build coercion
+	 * nodes that are equal() to both explicit and implicit coercions.
+	 */
+	if (a->coercionformat != b->coercionformat &&
+		a->coercionformat != COERCE_DONTCARE &&
+		b->coercionformat != COERCE_DONTCARE)
+		return false;
 
 	return true;
 }
 
 static bool
-_equalConstraintTestValue(ConstraintTestValue *a, ConstraintTestValue *b)
+_equalCoerceToDomainValue(CoerceToDomainValue *a, CoerceToDomainValue *b)
 {
 	COMPARE_SCALAR_FIELD(typeId);
 	COMPARE_SCALAR_FIELD(typeMod);
@@ -1599,11 +1605,11 @@ equal(void *a, void *b)
 		case T_BooleanTest:
 			retval = _equalBooleanTest(a, b);
 			break;
-		case T_ConstraintTest:
-			retval = _equalConstraintTest(a, b);
+		case T_CoerceToDomain:
+			retval = _equalCoerceToDomain(a, b);
 			break;
-		case T_ConstraintTestValue:
-			retval = _equalConstraintTestValue(a, b);
+		case T_CoerceToDomainValue:
+			retval = _equalCoerceToDomainValue(a, b);
 			break;
 		case T_TargetEntry:
 			retval = _equalTargetEntry(a, b);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index fd18c957d9..ea6305512c 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v 1.194 2003/01/20 18:54:47 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v 1.195 2003/02/03 21:15:44 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -745,21 +745,20 @@ _outBooleanTest(StringInfo str, BooleanTest *node)
 }
 
 static void
-_outConstraintTest(StringInfo str, ConstraintTest *node)
+_outCoerceToDomain(StringInfo str, CoerceToDomain *node)
 {
-	WRITE_NODE_TYPE("CONSTRAINTTEST");
+	WRITE_NODE_TYPE("COERCETODOMAIN");
 
 	WRITE_NODE_FIELD(arg);
-	WRITE_ENUM_FIELD(testtype, ConstraintTestType);
-	WRITE_STRING_FIELD(name);
-	WRITE_STRING_FIELD(domname);
-	WRITE_NODE_FIELD(check_expr);
+	WRITE_OID_FIELD(resulttype);
+	WRITE_INT_FIELD(resulttypmod);
+	WRITE_ENUM_FIELD(coercionformat, CoercionForm);
 }
 
 static void
-_outConstraintTestValue(StringInfo str, ConstraintTestValue *node)
+_outCoerceToDomainValue(StringInfo str, CoerceToDomainValue *node)
 {
-	WRITE_NODE_TYPE("CONSTRAINTTESTVALUE");
+	WRITE_NODE_TYPE("COERCETODOMAINVALUE");
 
 	WRITE_OID_FIELD(typeId);
 	WRITE_INT_FIELD(typeMod);
@@ -1548,11 +1547,11 @@ _outNode(StringInfo str, void *obj)
 			case T_BooleanTest:
 				_outBooleanTest(str, obj);
 				break;
-			case T_ConstraintTest:
-				_outConstraintTest(str, obj);
+			case T_CoerceToDomain:
+				_outCoerceToDomain(str, obj);
 				break;
-			case T_ConstraintTestValue:
-				_outConstraintTestValue(str, obj);
+			case T_CoerceToDomainValue:
+				_outCoerceToDomainValue(str, obj);
 				break;
 			case T_TargetEntry:
 				_outTargetEntry(str, obj);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 457e04eb9f..fe4831ee9f 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.146 2003/01/10 21:08:11 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.147 2003/02/03 21:15:44 tgl Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -635,29 +635,28 @@ _readBooleanTest(void)
 }
 
 /*
- * _readConstraintTest
+ * _readCoerceToDomain
  */
-static ConstraintTest *
-_readConstraintTest(void)
+static CoerceToDomain *
+_readCoerceToDomain(void)
 {
-	READ_LOCALS(ConstraintTest);
+	READ_LOCALS(CoerceToDomain);
 
 	READ_NODE_FIELD(arg);
-	READ_ENUM_FIELD(testtype, ConstraintTestType);
-	READ_STRING_FIELD(name);
-	READ_STRING_FIELD(domname);
-	READ_NODE_FIELD(check_expr);
+	READ_OID_FIELD(resulttype);
+	READ_INT_FIELD(resulttypmod);
+	READ_ENUM_FIELD(coercionformat, CoercionForm);
 
 	READ_DONE();
 }
 
 /*
- * _readConstraintTestValue
+ * _readCoerceToDomainValue
  */
-static ConstraintTestValue *
-_readConstraintTestValue(void)
+static CoerceToDomainValue *
+_readCoerceToDomainValue(void)
 {
-	READ_LOCALS(ConstraintTestValue);
+	READ_LOCALS(CoerceToDomainValue);
 
 	READ_OID_FIELD(typeId);
 	READ_INT_FIELD(typeMod);
@@ -900,10 +899,10 @@ parseNodeString(void)
 		return_value = _readNullTest();
 	else if (MATCH("BOOLEANTEST", 11))
 		return_value = _readBooleanTest();
-	else if (MATCH("CONSTRAINTTEST", 14))
-		return_value = _readConstraintTest();
-	else if (MATCH("CONSTRAINTTESTVALUE", 19))
-		return_value = _readConstraintTestValue();
+	else if (MATCH("COERCETODOMAIN", 14))
+		return_value = _readCoerceToDomain();
+	else if (MATCH("COERCETODOMAINVALUE", 19))
+		return_value = _readCoerceToDomainValue();
 	else if (MATCH("TARGETENTRY", 11))
 		return_value = _readTargetEntry();
 	else if (MATCH("RANGETBLREF", 11))
diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c
index 9df0a79478..8fe67ec475 100644
--- a/src/backend/optimizer/path/clausesel.c
+++ b/src/backend/optimizer/path/clausesel.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/clausesel.c,v 1.56 2003/01/28 22:13:29 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/clausesel.c,v 1.57 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -540,6 +540,14 @@ clause_selectivity(Query *root,
 								varRelid,
 								jointype);
 	}
+	else if (IsA(clause, CoerceToDomain))
+	{
+		/* Not sure this case is needed, but it can't hurt */
+		s1 = clause_selectivity(root,
+								(Node *) ((CoerceToDomain *) clause)->arg,
+								varRelid,
+								jointype);
+	}
 
 #ifdef SELECTIVITY_DEBUG
 	elog(DEBUG3, "clause_selectivity: s1 %f", s1);
diff --git a/src/backend/optimizer/prep/preptlist.c b/src/backend/optimizer/prep/preptlist.c
index 87d3c983a7..dc8faa9d83 100644
--- a/src/backend/optimizer/prep/preptlist.c
+++ b/src/backend/optimizer/prep/preptlist.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/prep/preptlist.c,v 1.59 2002/12/12 15:49:32 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/prep/preptlist.c,v 1.60 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -185,9 +185,10 @@ expand_targetlist(List *tlist, int command_type,
 												  true, /* isnull */
 												  att_tup->attbyval);
 					if (!att_tup->attisdropped)
-						new_expr = coerce_type_constraints(new_expr,
-														   atttype,
-														   COERCE_IMPLICIT_CAST);
+						new_expr = coerce_to_domain(new_expr,
+													InvalidOid,
+													atttype,
+													COERCE_IMPLICIT_CAST);
 					break;
 				case CMD_UPDATE:
 					/* Insert NULLs for dropped columns */
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 253c9e8813..f0b8ab1262 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.125 2003/01/20 18:54:54 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.126 2003/02/03 21:15:44 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -2030,7 +2030,7 @@ expression_tree_walker(Node *node,
 		case T_Var:
 		case T_Const:
 		case T_Param:
-		case T_ConstraintTestValue:
+		case T_CoerceToDomainValue:
 		case T_RangeTblRef:
 			/* primitive node types with no subnodes */
 			break;
@@ -2148,10 +2148,8 @@ expression_tree_walker(Node *node,
 			return walker(((NullTest *) node)->arg, context);
 		case T_BooleanTest:
 			return walker(((BooleanTest *) node)->arg, context);
-		case T_ConstraintTest:
-			if (walker(((ConstraintTest *) node)->arg, context))
-				return true;
-			return walker(((ConstraintTest *) node)->check_expr, context);
+		case T_CoerceToDomain:
+			return walker(((CoerceToDomain *) node)->arg, context);
 		case T_TargetEntry:
 			return walker(((TargetEntry *) node)->expr, context);
 		case T_Query:
@@ -2374,7 +2372,7 @@ expression_tree_mutator(Node *node,
 		case T_Var:
 		case T_Const:
 		case T_Param:
-		case T_ConstraintTestValue:
+		case T_CoerceToDomainValue:
 		case T_RangeTblRef:
 			/* primitive node types with no subnodes */
 			return (Node *) copyObject(node);
@@ -2538,14 +2536,13 @@ expression_tree_mutator(Node *node,
 				return (Node *) newnode;
 			}
 			break;
-		case T_ConstraintTest:
+		case T_CoerceToDomain:
 			{
-				ConstraintTest *ctest = (ConstraintTest *) node;
-				ConstraintTest *newnode;
+				CoerceToDomain *ctest = (CoerceToDomain *) node;
+				CoerceToDomain *newnode;
 
-				FLATCOPY(newnode, ctest, ConstraintTest);
+				FLATCOPY(newnode, ctest, CoerceToDomain);
 				MUTATE(newnode->arg, ctest->arg, Expr *);
-				MUTATE(newnode->check_expr, ctest->check_expr, Expr *);
 				return (Node *) newnode;
 			}
 			break;
diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index af184eca6d..46d191a915 100644
--- a/src/backend/parser/parse_coerce.c
+++ b/src/backend/parser/parse_coerce.c
@@ -8,18 +8,13 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.91 2002/12/12 20:35:13 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.92 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
 
-#include "access/genam.h"
-#include "access/heapam.h"
-#include "catalog/catname.h"
-#include "catalog/indexing.h"
 #include "catalog/pg_cast.h"
-#include "catalog/pg_constraint.h"
 #include "catalog/pg_proc.h"
 #include "nodes/makefuncs.h"
 #include "optimizer/clauses.h"
@@ -35,7 +30,7 @@
 
 static Node *coerce_type_typmod(Node *node,
 								Oid targetTypeId, int32 targetTypMod,
-								CoercionForm cformat);
+								CoercionForm cformat, bool isExplicit);
 static Oid	PreferredType(CATEGORY category, Oid type);
 static Node *build_func_call(Oid funcid, Oid rettype, List *args,
 							 CoercionForm fformat);
@@ -103,7 +98,9 @@ coerce_to_target_type(Node *expr, Oid exprtype,
 	 * as well as a type coercion.
 	 */
 	if (expr != NULL)
-		expr = coerce_type_typmod(expr, targettype, targettypmod, cformat);
+		expr = coerce_type_typmod(expr, targettype, targettypmod,
+								  cformat,
+								  (cformat != COERCE_IMPLICIT_CAST));
 
 	return expr;
 }
@@ -119,7 +116,7 @@ coerce_to_target_type(Node *expr, Oid exprtype,
  * No coercion to a typmod (length) is performed here.  The caller must
  * call coerce_type_typmod as well, if a typmod constraint is wanted.
  * (But if the target type is a domain, it may internally contain a
- * typmod constraint, which will be applied inside coerce_type_constraints.)
+ * typmod constraint, which will be applied inside coerce_to_domain.)
  */
 Node *
 coerce_type(Node *node, Oid inputTypeId, Oid targetTypeId,
@@ -186,15 +183,8 @@ coerce_type(Node *node, Oid inputTypeId, Oid targetTypeId,
 
 		/* If target is a domain, apply constraints. */
 		if (targetTyptype == 'd')
-		{
-			result = coerce_type_constraints(result, targetTypeId,
-											 cformat);
-			/* We might now need a RelabelType. */
-			if (exprType(result) != targetTypeId)
-				result = (Node *) makeRelabelType((Expr *) result,
-												  targetTypeId, -1,
-												  cformat);
-		}
+			result = coerce_to_domain(result, InvalidOid, targetTypeId,
+									  cformat);
 
 		ReleaseSysCache(targetType);
 	}
@@ -222,17 +212,12 @@ coerce_type(Node *node, Oid inputTypeId, Oid targetTypeId,
 									 cformat);
 
 			/*
-			 * If domain, test against domain constraints and relabel with
+			 * If domain, coerce to the domain type and relabel with
 			 * domain type ID
 			 */
 			if (targetTypeId != baseTypeId)
-			{
-				result = coerce_type_constraints(result, targetTypeId,
-												 cformat);
-				result = (Node *) makeRelabelType((Expr *) result,
-												  targetTypeId, -1,
-												  cformat);
-			}
+				result = coerce_to_domain(result, baseTypeId, targetTypeId,
+										  cformat);
 
 			/*
 			 * If the input is a constant, apply the type conversion
@@ -257,21 +242,23 @@ coerce_type(Node *node, Oid inputTypeId, Oid targetTypeId,
 			 * higher-level code.
 			 *
 			 * Also, domains may have value restrictions beyond the base type
-			 * that must be accounted for.
+			 * that must be accounted for.  If the destination is a domain
+			 * then we won't need a RelabelType node.
 			 */
-			result = coerce_type_constraints(node, targetTypeId,
-											 cformat);
-
-			/*
-			 * XXX could we label result with exprTypmod(node) instead of
-			 * default -1 typmod, to save a possible length-coercion
-			 * later? Would work if both types have same interpretation of
-			 * typmod, which is likely but not certain (wrong if target is
-			 * a domain, in any case).
-			 */
-			result = (Node *) makeRelabelType((Expr *) result,
-											  targetTypeId, -1,
-											  cformat);
+			result = coerce_to_domain(node, InvalidOid, targetTypeId,
+									  cformat);
+			if (result == node)
+			{
+				/*
+				 * XXX could we label result with exprTypmod(node) instead of
+				 * default -1 typmod, to save a possible length-coercion
+				 * later? Would work if both types have same interpretation of
+				 * typmod, which is likely but not certain.
+				 */
+				result = (Node *) makeRelabelType((Expr *) result,
+												  targetTypeId, -1,
+												  cformat);
+			}
 		}
 	}
 	else if (typeInheritsFrom(inputTypeId, targetTypeId))
@@ -392,120 +379,61 @@ can_coerce_type(int nargs, Oid *input_typeids, Oid *target_typeids,
 
 
 /*
- * Create an expression tree to enforce the constraints (if any)
- * that should be applied by the type.	Currently this is only
- * interesting for domain types.
+ * Create an expression tree to represent coercion to a domain type.
+ *
+ * 'arg': input expression
+ * 'baseTypeId': base type of domain, if known (pass InvalidOid if caller
+ *		has not bothered to look this up)
+ * 'typeId': target type to coerce to
+ * 'cformat': coercion format
  *
- * NOTE: result tree is not guaranteed to show the correct exprType() for
- * the domain; it may show the base type.  Caller must relabel if needed.
+ * If the target type isn't a domain, the given 'arg' is returned as-is.
  */
 Node *
-coerce_type_constraints(Node *arg, Oid typeId, CoercionForm cformat)
+coerce_to_domain(Node *arg, Oid baseTypeId, Oid typeId, CoercionForm cformat)
 {
-	char	   *notNull = NULL;
-	int32		typmod = -1;
-
-	for (;;)
-	{
-		HeapTuple	tup;
-		HeapTuple	conTup;
-		Form_pg_type typTup;
-
-		ScanKeyData key[1];
-		int			nkeys = 0;
-		SysScanDesc scan;
-		Relation	conRel;
-		
-		tup = SearchSysCache(TYPEOID,
-							 ObjectIdGetDatum(typeId),
-							 0, 0, 0);
-		if (!HeapTupleIsValid(tup))
-			elog(ERROR, "coerce_type_constraints: failed to lookup type %u",
-				 typeId);
-		typTup = (Form_pg_type) GETSTRUCT(tup);
-
-		/* Test for NOT NULL Constraint */
-		if (typTup->typnotnull && notNull == NULL)
-			notNull = pstrdup(NameStr(typTup->typname));
-
-		/* Add CHECK Constraints to domains */
-		conRel = heap_openr(ConstraintRelationName, RowShareLock);
-
-		ScanKeyEntryInitialize(&key[nkeys++], 0x0,
-							   Anum_pg_constraint_contypid, F_OIDEQ,
-							   ObjectIdGetDatum(typeId));
-
-		scan = systable_beginscan(conRel, ConstraintTypidIndex, true,
-								  SnapshotNow, nkeys, key);
-
-		while (HeapTupleIsValid(conTup = systable_getnext(scan)))
-		{
-			Datum	val;
-			bool	isNull;
-			ConstraintTest *r = makeNode(ConstraintTest);
-			Form_pg_constraint	c = (Form_pg_constraint) GETSTRUCT(conTup);
-
-			/* Not expecting conbin to be NULL, but we'll test for it anyway */
-			val = fastgetattr(conTup,
-							  Anum_pg_constraint_conbin,
-							  conRel->rd_att, &isNull);
-
-			if (isNull)
-				elog(ERROR, "coerce_type_constraints: domain %s constraint %s has NULL conbin",
-					 NameStr(typTup->typname), NameStr(c->conname));
-
-			r->arg = (Expr *) arg;
-			r->testtype = CONSTR_TEST_CHECK;
-			r->name = NameStr(c->conname);
-			r->domname = NameStr(typTup->typname);
-			r->check_expr =	stringToNode(DatumGetCString(DirectFunctionCall1(textout,
-																			 val)));
-
-			arg = (Node *) r;
-		}
-
-		systable_endscan(scan);
-		heap_close(conRel, RowShareLock);
-
-		if (typTup->typtype != 'd')
-		{
-			/* Not a domain, so done */
-			ReleaseSysCache(tup);
-			break;
-		}
+	CoerceToDomain *result;
+	int32	typmod;
 
-		Assert(typmod < 0);
+	/* Get the base type if it hasn't been supplied */
+	if (baseTypeId == InvalidOid)
+		baseTypeId = getBaseType(typeId);
 
-		typeId = typTup->typbasetype;
-		typmod = typTup->typtypmod;
-		ReleaseSysCache(tup);
-	}
+	/* If it isn't a domain, return the node as it was passed in */
+	if (baseTypeId == typeId)
+		return arg;
 
 	/*
-	 * If domain applies a typmod to its base type, do length coercion.
+	 * If the domain applies a typmod to its base type, build the appropriate
+	 * coercion step.  Mark it implicit for display purposes, because we don't
+	 * want it shown separately by ruleutils.c; but the isExplicit flag passed
+	 * to the conversion function depends on the manner in which the domain
+	 * coercion is invoked, so that the semantics of implicit and explicit
+	 * coercion differ.  (Is that really the behavior we want?)
+	 *
+	 * NOTE: because we apply this as part of the fixed expression structure,
+	 * ALTER DOMAIN cannot alter the typtypmod.  But it's unclear that that
+	 * would be safe to do anyway, without lots of knowledge about what the
+	 * base type thinks the typmod means.
 	 */
+	typmod = get_typtypmod(typeId);
 	if (typmod >= 0)
-		arg = coerce_type_typmod(arg, typeId, typmod, cformat);
+		arg = coerce_type_typmod(arg, baseTypeId, typmod,
+								 COERCE_IMPLICIT_CAST,
+								 (cformat != COERCE_IMPLICIT_CAST));
 
 	/*
-	 * Only need to add one NOT NULL check regardless of how many domains
-	 * in the stack request it.  The topmost domain that requested it is
-	 * used as the constraint name.
+	 * Now build the domain coercion node.  This represents run-time checking
+	 * of any constraints currently attached to the domain.  This also
+	 * ensures that the expression is properly labeled as to result type.
 	 */
-	if (notNull)
-	{
-		ConstraintTest *r = makeNode(ConstraintTest);
-
-		r->arg = (Expr *) arg;
-		r->testtype = CONSTR_TEST_NOTNULL;
-		r->name = "NOT NULL";
-		r->domname = notNull;
-		r->check_expr = NULL;
-
-		arg = (Node *) r;
-	}
+	result = makeNode(CoerceToDomain);
+	result->arg = (Expr *) arg;
+	result->resulttype = typeId;
+	result->resulttypmod = -1;	/* currently, always -1 for domains */
+	result->coercionformat = cformat;
 
-	return arg;
+	return (Node *) result;
 }
 
 
@@ -526,7 +454,7 @@ coerce_type_constraints(Node *arg, Oid typeId, CoercionForm cformat)
  */
 static Node *
 coerce_type_typmod(Node *node, Oid targetTypeId, int32 targetTypMod,
-				   CoercionForm cformat)
+				   CoercionForm cformat, bool isExplicit)
 {
 	Oid			funcId;
 	int			nargs;
@@ -559,7 +487,7 @@ coerce_type_typmod(Node *node, Oid targetTypeId, int32 targetTypMod,
 			/* Pass it a boolean isExplicit parameter, too */
 			cons = makeConst(BOOLOID,
 							 sizeof(bool),
-							 BoolGetDatum(cformat != COERCE_IMPLICIT_CAST),
+							 BoolGetDatum(isExplicit),
 							 false,
 							 true);
 
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 5ee64cf38e..95b3a6297a 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.141 2003/01/13 00:18:51 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.142 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -674,8 +674,8 @@ transformExpr(ParseState *pstate, Node *expr)
 		case T_ArrayRef:
 		case T_FieldSelect:
 		case T_RelabelType:
-		case T_ConstraintTest:
-		case T_ConstraintTestValue:
+		case T_CoerceToDomain:
+		case T_CoerceToDomainValue:
 			{
 				result = (Node *) expr;
 				break;
@@ -1017,11 +1017,11 @@ exprType(Node *expr)
 		case T_BooleanTest:
 			type = BOOLOID;
 			break;
-		case T_ConstraintTest:
-			type = exprType((Node *) ((ConstraintTest *) expr)->arg);
+		case T_CoerceToDomain:
+			type = ((CoerceToDomain *) expr)->resulttype;
 			break;
-		case T_ConstraintTestValue:
-			type = ((ConstraintTestValue *) expr)->typeId;
+		case T_CoerceToDomainValue:
+			type = ((CoerceToDomainValue *) expr)->typeId;
 			break;
 		case T_RangeVar:
 			/*
@@ -1117,10 +1117,10 @@ exprTypmod(Node *expr)
 				return typmod;
 			}
 			break;
-		case T_ConstraintTest:
-			return exprTypmod((Node *) ((ConstraintTest *) expr)->arg);
-		case T_ConstraintTestValue:
-			return ((ConstraintTestValue *) expr)->typeMod;
+		case T_CoerceToDomain:
+			return ((CoerceToDomain *) expr)->resulttypmod;
+		case T_CoerceToDomainValue:
+			return ((CoerceToDomainValue *) expr)->typeMod;
 		default:
 			break;
 	}
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index df5890358b..10ee725b30 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -3,7 +3,7 @@
  *				back to source text
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.133 2003/02/03 15:17:24 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.134 2003/02/03 21:15:44 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -638,11 +638,11 @@ pg_get_constraintdef(PG_FUNCTION_ARGS)
 				}
 				appendStringInfo(&buf, "%s", string);
 
-				/* Add ON UPDATE and ON DELETE clauses */
+				/* Add ON UPDATE and ON DELETE clauses, if needed */
 				switch (conForm->confupdtype)
 				{
 					case FKCONSTR_ACTION_NOACTION:
-						string = "";
+						string = NULL; /* suppress default */
 						break;
 					case FKCONSTR_ACTION_RESTRICT:
 						string = "RESTRICT";
@@ -659,16 +659,16 @@ pg_get_constraintdef(PG_FUNCTION_ARGS)
 					default:
 						elog(ERROR, "pg_get_constraintdef: Unknown confupdtype '%c' for constraint %u",
 							 conForm->confupdtype, constraintId);
-						string = "";	/* keep compiler quiet */
+						string = NULL;	/* keep compiler quiet */
 						break;
 				}
-				if (strlen(string) != 0)
+				if (string)
 					appendStringInfo(&buf, " ON UPDATE %s", string);
 
 				switch (conForm->confdeltype)
 				{
 					case FKCONSTR_ACTION_NOACTION:
-						string = "";
+						string = NULL; /* suppress default */
 						break;
 					case FKCONSTR_ACTION_RESTRICT:
 						string = "RESTRICT";
@@ -685,10 +685,10 @@ pg_get_constraintdef(PG_FUNCTION_ARGS)
 					default:
 						elog(ERROR, "pg_get_constraintdef: Unknown confdeltype '%c' for constraint %u",
 							 conForm->confdeltype, constraintId);
-						string = "";	/* keep compiler quiet */
+						string = NULL;	/* keep compiler quiet */
 						break;
 				}
-				if (strlen(string) != 0)
+				if (string)
 					appendStringInfo(&buf, " ON DELETE %s", string);
 
 				if (conForm->condeferrable)
@@ -2252,19 +2252,34 @@ get_rule_expr(Node *node, deparse_context *context,
 			}
 			break;
 
-		case T_ConstraintTest:
+		case T_CoerceToDomain:
 			{
-				ConstraintTest *ctest = (ConstraintTest *) node;
+				CoerceToDomain *ctest = (CoerceToDomain *) node;
+				Node   *arg = (Node *) ctest->arg;
 
 				/*
-				 * We assume that the operations of the constraint node
-				 * need not be explicitly represented in the output.
+				 * Any implicit coercion at the top level of the argument
+				 * is presumably due to the domain's own internal typmod
+				 * coercion, so do not force it to be shown.
 				 */
-				get_rule_expr((Node *) ctest->arg, context, showimplicit);
+				if (ctest->coercionformat == COERCE_IMPLICIT_CAST &&
+					!showimplicit)
+				{
+					/* don't show the implicit cast */
+					get_rule_expr(arg, context, false);
+				}
+				else
+				{
+					appendStringInfoChar(buf, '(');
+					get_rule_expr(arg, context, false);
+					appendStringInfo(buf, ")::%s",
+							format_type_with_typemod(ctest->resulttype,
+													 ctest->resulttypmod));
+				}
 			}
 			break;
 
-		case T_ConstraintTestValue:
+		case T_CoerceToDomainValue:
 			appendStringInfo(buf, "VALUE");
 			break;
 
@@ -2444,7 +2459,8 @@ get_agg_expr(Aggref *aggref, deparse_context *context)
  * the expression tree has a length-coercion node atop a type-coercion node.
  *
  * Note: avoid stripping a length-coercion node, since two successive
- * coercions to different lengths aren't a no-op.
+ * coercions to different lengths aren't a no-op.  Also, never strip a
+ * CoerceToDomain node, even though it might be effectively just RelabelType.
  */
 static Node *
 strip_type_coercion(Node *expr, Oid resultType)
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index a6c838974c..abc00a9204 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.89 2003/01/15 19:35:44 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/lsyscache.c,v 1.90 2003/02/03 21:15:44 tgl Exp $
  *
  * NOTES
  *	  Eventually, the index information should go through here, too.
@@ -1012,6 +1012,33 @@ get_typstorage(Oid typid)
 		return 'p';
 }
 
+/*
+ * get_typtypmod
+ *
+ *		Given the type OID, return the typtypmod field (domain's typmod
+ *		for base type)
+ */
+int32
+get_typtypmod(Oid typid)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache(TYPEOID,
+						ObjectIdGetDatum(typid),
+						0, 0, 0);
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_type typtup = (Form_pg_type) GETSTRUCT(tp);
+		int32		result;
+
+		result = typtup->typtypmod;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return -1;
+}
+
 /*
  * get_typdefault
  *	  Given a type OID, return the type's default value, if any.
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index d234eb3289..df4347633f 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: catversion.h,v 1.174 2003/01/28 22:13:36 tgl Exp $
+ * $Id: catversion.h,v 1.175 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200301281
+#define CATALOG_VERSION_NO	200302031
 
 #endif
diff --git a/src/include/commands/typecmds.h b/src/include/commands/typecmds.h
index fde284efea..0d2e319ed4 100644
--- a/src/include/commands/typecmds.h
+++ b/src/include/commands/typecmds.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: typecmds.h,v 1.4 2003/01/09 18:00:24 tgl Exp $
+ * $Id: typecmds.h,v 1.5 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -32,6 +32,8 @@ extern void AlterDomainAddConstraint(List *names, Node *constr);
 extern void AlterDomainDropConstraint(List *names, const char *constrName,
 									  DropBehavior behavior);
 
+extern List *GetDomainConstraints(Oid typeOid);
+
 extern void AlterTypeOwner(List *names, AclId newOwnerSysId);
 
 #endif   /* TYPECMDS_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 98c6f1ddfb..ccb2532066 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: execnodes.h,v 1.92 2003/01/23 05:10:41 tgl Exp $
+ * $Id: execnodes.h,v 1.93 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -114,7 +114,7 @@ typedef struct ExprContext
 	Datum	   *ecxt_aggvalues; /* precomputed values for Aggref nodes */
 	bool	   *ecxt_aggnulls;	/* null flags for Aggref nodes */
 
-	/* Value to substitute for ConstraintTestValue nodes in expression */
+	/* Value to substitute for CoerceToDomainValue nodes in expression */
 	Datum		domainValue_datum;
 	bool		domainValue_isNull;
 
@@ -539,15 +539,37 @@ typedef struct CaseWhenState
 } CaseWhenState;
 
 /* ----------------
- *		ConstraintTestState node
+ *		CoerceToDomainState node
  * ----------------
  */
-typedef struct ConstraintTestState
+typedef struct CoerceToDomainState
 {
 	ExprState	xprstate;
 	ExprState  *arg;			/* input expression */
-	ExprState  *check_expr;		/* for CHECK test, a boolean expression */
-} ConstraintTestState;
+	/* Cached list of constraints that need to be checked */
+	List	   *constraints;	/* list of DomainConstraintState nodes */
+} CoerceToDomainState;
+
+/*
+ * DomainConstraintState - one item to check during CoerceToDomain
+ *
+ * Note: this is just a Node, and not an ExprState, because it has no
+ * corresponding Expr to link to.  Nonetheless it is part of an ExprState
+ * tree, so we give it a name following the xxxState convention.
+ */
+typedef enum DomainConstraintType
+{
+	DOM_CONSTRAINT_NOTNULL,
+	DOM_CONSTRAINT_CHECK
+} DomainConstraintType;
+
+typedef struct DomainConstraintState
+{
+	NodeTag		type;
+	DomainConstraintType constrainttype; /* constraint type */
+	char	   *name;			/* name of constraint (for error msgs) */
+	ExprState  *check_expr;		/* for CHECK, a boolean expression */
+} DomainConstraintState;
 
 
 /* ----------------------------------------------------------------
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index bf8bb1719e..a218790194 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: nodes.h,v 1.135 2003/01/20 18:55:00 tgl Exp $
+ * $Id: nodes.h,v 1.136 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -114,8 +114,8 @@ typedef enum NodeTag
 	T_CaseWhen,
 	T_NullTest,
 	T_BooleanTest,
-	T_ConstraintTest,
-	T_ConstraintTestValue,
+	T_CoerceToDomain,
+	T_CoerceToDomainValue,
 	T_TargetEntry,
 	T_RangeTblRef,
 	T_JoinExpr,
@@ -136,7 +136,8 @@ typedef enum NodeTag
 	T_SubPlanState,
 	T_CaseExprState,
 	T_CaseWhenState,
-	T_ConstraintTestState,
+	T_CoerceToDomainState,
+	T_DomainConstraintState,
 
 	/*
 	 * TAGS FOR PLANNER NODES (relation.h)
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index b187c98fdc..ad1c736125 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -10,7 +10,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: primnodes.h,v 1.77 2003/01/10 21:08:15 tgl Exp $
+ * $Id: primnodes.h,v 1.78 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -578,28 +578,22 @@ typedef struct BooleanTest
 } BooleanTest;
 
 /*
- * ConstraintTest
+ * CoerceToDomain
  *
- * ConstraintTest represents the operation of testing a value to see whether
- * it meets a constraint.  If so, the input value is returned as the result;
- * if not, an error is raised.
+ * CoerceToDomain represents the operation of coercing a value to a domain
+ * type.  At runtime (and not before) the precise set of constraints to be
+ * checked will be determined.  If the value passes, it is returned as the
+ * result; if not, an error is raised.  Note that this is equivalent to
+ * RelabelType in the scenario where no constraints are applied.
  */
-
-typedef enum ConstraintTestType
-{
-	CONSTR_TEST_NOTNULL,
-	CONSTR_TEST_CHECK
-} ConstraintTestType;
-
-typedef struct ConstraintTest
+typedef struct CoerceToDomain
 {
 	Expr		xpr;
 	Expr	   *arg;			/* input expression */
-	ConstraintTestType testtype;	/* test type */
-	char	   *name;			/* name of constraint (for error msgs) */
-	char	   *domname; 		/* name of domain (for error messages) */
-	Expr	   *check_expr;		/* for CHECK test, a boolean expression */
-} ConstraintTest;
+	Oid			resulttype;		/* domain type ID (result type) */
+	int32		resulttypmod;	/* output typmod (currently always -1) */
+	CoercionForm coercionformat; /* how to display this node */
+} CoerceToDomain;
 
 /*
  * Placeholder node for the value to be processed by a domain's check
@@ -610,12 +604,12 @@ typedef struct ConstraintTest
  * the domain itself.  This is because we shouldn't consider the value to
  * be a member of the domain if we haven't yet checked its constraints.
  */
-typedef struct ConstraintTestValue
+typedef struct CoerceToDomainValue
 {
 	Expr		xpr;
 	Oid			typeId;			/* type for substituted value */
 	int32		typeMod;		/* typemod for substituted value */
-} ConstraintTestValue;
+} CoerceToDomainValue;
 
 
 /*
diff --git a/src/include/parser/parse_coerce.h b/src/include/parser/parse_coerce.h
index ecc61ea716..ae12f46f62 100644
--- a/src/include/parser/parse_coerce.h
+++ b/src/include/parser/parse_coerce.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parse_coerce.h,v 1.48 2002/10/24 22:09:00 tgl Exp $
+ * $Id: parse_coerce.h,v 1.49 2003/02/03 21:15:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -45,8 +45,8 @@ extern bool can_coerce_type(int nargs, Oid *input_typeids, Oid *target_typeids,
 							CoercionContext ccontext);
 extern Node *coerce_type(Node *node, Oid inputTypeId, Oid targetTypeId,
 						 CoercionContext ccontext, CoercionForm cformat);
-extern Node *coerce_type_constraints(Node *arg, Oid typeId,
-									 CoercionForm cformat);
+extern Node *coerce_to_domain(Node *arg, Oid baseTypeId, Oid typeId,
+							  CoercionForm cformat);
 
 extern Node *coerce_to_boolean(Node *node, const char *constructName);
 
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 8200730f6a..d6f9447d19 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: lsyscache.h,v 1.66 2003/01/15 19:35:47 tgl Exp $
+ * $Id: lsyscache.h,v 1.67 2003/02/03 21:15:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,6 +54,7 @@ extern void get_typlenbyval(Oid typid, int16 *typlen, bool *typbyval);
 extern void get_typlenbyvalalign(Oid typid, int16 *typlen, bool *typbyval,
 					 char *typalign);
 extern char get_typstorage(Oid typid);
+extern int32 get_typtypmod(Oid typid);
 extern Node *get_typdefault(Oid typid);
 extern char get_typtype(Oid typid);
 extern Oid	get_typ_typrelid(Oid typid);
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index c9fd9418b4..7d4785ef7d 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -3,7 +3,7 @@
  *			  procedural language
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.77 2003/01/21 22:06:12 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.78 2003/02/03 21:15:45 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -3634,6 +3634,9 @@ exec_simple_check_node(Node *node)
 		case T_BooleanTest:
 			return exec_simple_check_node((Node *) ((BooleanTest *) node)->arg);
 
+		case T_CoerceToDomain:
+			return exec_simple_check_node((Node *) ((CoerceToDomain *) node)->arg);
+
 		case T_List:
 			{
 				List	   *expr = (List *) node;
diff --git a/src/test/regress/expected/domain.out b/src/test/regress/expected/domain.out
index e48120a68d..1aaa4a85ef 100644
--- a/src/test/regress/expected/domain.out
+++ b/src/test/regress/expected/domain.out
@@ -257,14 +257,49 @@ ERROR:  ALTER DOMAIN: Relation "domcontest" attribute "col1" contains values tha
 alter domain con add constraint t check (VALUE < 34);
 alter domain con add check (VALUE > 0);
 insert into domcontest values (-5); -- fails
-ERROR:  ExecEvalConstraintTest: Domain con constraint $1 failed
+ERROR:  ExecEvalCoerceToDomain: Domain con constraint $1 failed
 insert into domcontest values (42); -- fails
-ERROR:  ExecEvalConstraintTest: Domain con constraint t failed
+ERROR:  ExecEvalCoerceToDomain: Domain con constraint t failed
 insert into domcontest values (5);
 alter domain con drop constraint t;
 insert into domcontest values (-5); --fails
-ERROR:  ExecEvalConstraintTest: Domain con constraint $1 failed
+ERROR:  ExecEvalCoerceToDomain: Domain con constraint $1 failed
 insert into domcontest values (42);
+-- Confirm ALTER DOMAIN with RULES.
+create table domtab (col1 integer);
+create domain dom as integer;
+create view domview as select cast(col1 as dom) from domtab;
+insert into domtab (col1) values (null);
+insert into domtab (col1) values (5);
+select * from domview;
+ col1 
+------
+ 
+ 5
+(2 rows)
+
+alter domain dom set not null;
+select * from domview; -- fail
+ERROR:  Domain dom does not allow NULL values
+alter domain dom drop not null;
+select * from domview;
+ col1 
+------
+ 
+ 5
+(2 rows)
+
+alter domain dom add constraint domchkgt6 check(value > 6);
+select * from domview; --fail
+ERROR:  ExecEvalCoerceToDomain: Domain dom constraint domchkgt6 failed
+alter domain dom drop constraint domchkgt6 restrict;
+select * from domview;
+ col1 
+------
+ 
+ 5
+(2 rows)
+
 -- cleanup
 drop domain ddef1 restrict;
 drop domain ddef2 restrict;
diff --git a/src/test/regress/sql/domain.sql b/src/test/regress/sql/domain.sql
index 76060e99c8..00a38f449c 100644
--- a/src/test/regress/sql/domain.sql
+++ b/src/test/regress/sql/domain.sql
@@ -224,6 +224,26 @@ alter domain con drop constraint t;
 insert into domcontest values (-5); --fails
 insert into domcontest values (42);
 
+-- Confirm ALTER DOMAIN with RULES.
+create table domtab (col1 integer);
+create domain dom as integer;
+create view domview as select cast(col1 as dom) from domtab;
+insert into domtab (col1) values (null);
+insert into domtab (col1) values (5);
+select * from domview;
+
+alter domain dom set not null;
+select * from domview; -- fail
+
+alter domain dom drop not null;
+select * from domview;
+
+alter domain dom add constraint domchkgt6 check(value > 6);
+select * from domview; --fail
+
+alter domain dom drop constraint domchkgt6 restrict;
+select * from domview;
+
 -- cleanup
 drop domain ddef1 restrict;
 drop domain ddef2 restrict;
-- 
2.40.0