Remove collation information from TypeName, where it does not belong.

The initial collations patch treated a COLLATE spec as part of a TypeName,
following what can only be described as brain fade on the part of the SQL
committee.  It's a lot more reasonable to treat COLLATE as a syntactically
separate object, so that it can be added in only the productions where it
actually belongs, rather than needing to reject it in a boatload of places
where it doesn't belong (something the original patch mostly failed to do).
In addition this change lets us meet the spec's requirement to allow
COLLATE anywhere in the clauses of a ColumnDef, and it avoids unfriendly
behavior for constructs such as "foo::type COLLATE collation".

To do this, pull collation information out of TypeName and put it in
ColumnDef instead, thus reverting most of the collation-related changes in
parse_type.c's API.  I made one additional structural change, which was to
use a ColumnDef as an intermediate node in AT_AlterColumnType AlterTableCmd
nodes.  This provides enough room to get rid of the "transform" wart in
AlterTableCmd too, since the ColumnDef can carry the USING expression
easily enough.

Also fix some other minor bugs that have crept in in the same areas,
like failure to copy recently-added fields of ColumnDef in copyfuncs.c.

While at it, document the formerly secret ability to specify a collation
in ALTER TABLE ALTER COLUMN TYPE, ALTER TYPE ADD ATTRIBUTE, and
ALTER TYPE ALTER ATTRIBUTE TYPE; and correct some misstatements about
what the default collation selection will be when COLLATE is omitted.

BTW, the three-parameter form of format_type() should go away too,
since it just contributes to the confusion in this area; but I'll do
that in a separate patch.

24 files changed, 397 insertions, 236 deletions

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 0cd1f941e3f..d78b08381e0 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -559,7 +559,8 @@ BuildDescForRelation(List *schema)
 		attnum++;
 
 		attname = entry->colname;
-		typenameTypeIdModColl(NULL, entry->typeName, &atttypid, &atttypmod, &attcollation);
+		typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
+		attcollation = GetColumnDefCollation(NULL, entry, atttypid);
 		attdim = list_length(entry->typeName->arrayBounds);
 
 		if (entry->typeName->setof)
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index 18e88d2653f..a52cb351ac8 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -98,7 +98,7 @@ DefineCollation(List *names, List *parameters)
 		Oid			collid;
 		HeapTuple	tp;
 
-		collid = LookupCollation(NULL, defGetQualifiedName(fromEl), -1);
+		collid =  get_collation_oid(defGetQualifiedName(fromEl), false);
 		tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
 		if (!HeapTupleIsValid(tp))
 			elog(ERROR, "cache lookup failed for collation %u", collid);
diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 3f25b3bf02a..a8ef947240e 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -87,7 +87,7 @@ compute_return_type(TypeName *returnType, Oid languageOid,
 	Oid			rettype;
 	Type		typtup;
 
-	typtup = LookupTypeName(NULL, returnType, NULL, NULL);
+	typtup = LookupTypeName(NULL, returnType, NULL);
 
 	if (typtup)
 	{
@@ -207,7 +207,7 @@ examine_parameter_list(List *parameters, Oid languageOid,
 		Oid			toid;
 		Type		typtup;
 
-		typtup = LookupTypeName(NULL, t, NULL, NULL);
+		typtup = LookupTypeName(NULL, t, NULL);
 		if (typtup)
 		{
 			if (!((Form_pg_type) GETSTRUCT(typtup))->typisdefined)
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index e71c311faf7..5c6212c64cd 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -139,9 +139,12 @@ DefineSequence(CreateSeqStmt *seq)
 		coldef->inhcount = 0;
 		coldef->is_local = true;
 		coldef->is_not_null = true;
+		coldef->is_from_type = false;
 		coldef->storage = 0;
 		coldef->raw_default = NULL;
 		coldef->cooked_default = NULL;
+		coldef->collClause = NULL;
+		coldef->collOid = InvalidOid;
 		coldef->constraints = NIL;
 
 		null[i - 1] = false;
@@ -149,53 +152,53 @@ DefineSequence(CreateSeqStmt *seq)
 		switch (i)
 		{
 			case SEQ_COL_NAME:
-				coldef->typeName = makeTypeNameFromOid(NAMEOID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(NAMEOID, -1);
 				coldef->colname = "sequence_name";
 				namestrcpy(&name, seq->sequence->relname);
 				value[i - 1] = NameGetDatum(&name);
 				break;
 			case SEQ_COL_LASTVAL:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
 				coldef->colname = "last_value";
 				value[i - 1] = Int64GetDatumFast(new.last_value);
 				break;
 			case SEQ_COL_STARTVAL:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
 				coldef->colname = "start_value";
 				value[i - 1] = Int64GetDatumFast(new.start_value);
 				break;
 			case SEQ_COL_INCBY:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
 				coldef->colname = "increment_by";
 				value[i - 1] = Int64GetDatumFast(new.increment_by);
 				break;
 			case SEQ_COL_MAXVALUE:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
 				coldef->colname = "max_value";
 				value[i - 1] = Int64GetDatumFast(new.max_value);
 				break;
 			case SEQ_COL_MINVALUE:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
 				coldef->colname = "min_value";
 				value[i - 1] = Int64GetDatumFast(new.min_value);
 				break;
 			case SEQ_COL_CACHE:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
 				coldef->colname = "cache_value";
 				value[i - 1] = Int64GetDatumFast(new.cache_value);
 				break;
 			case SEQ_COL_LOG:
-				coldef->typeName = makeTypeNameFromOid(INT8OID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(INT8OID, -1);
 				coldef->colname = "log_cnt";
 				value[i - 1] = Int64GetDatum((int64) 1);
 				break;
 			case SEQ_COL_CYCLE:
-				coldef->typeName = makeTypeNameFromOid(BOOLOID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(BOOLOID, -1);
 				coldef->colname = "is_cycled";
 				value[i - 1] = BoolGetDatum(new.is_cycled);
 				break;
 			case SEQ_COL_CALLED:
-				coldef->typeName = makeTypeNameFromOid(BOOLOID, -1, InvalidOid);
+				coldef->typeName = makeTypeNameFromOid(BOOLOID, -1);
 				coldef->colname = "is_called";
 				value[i - 1] = BoolGetDatum(false);
 				break;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 3be9a6f3481..f1264bfb66d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -339,7 +339,7 @@ static void ATPrepAlterColumnType(List **wqueue,
 					  AlterTableCmd *cmd, LOCKMODE lockmode);
 static bool ATColumnChangeRequiresRewrite(Node *expr, AttrNumber varattno);
 static void ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
-					  const char *colName, TypeName *typeName, LOCKMODE lockmode);
+								  AlterTableCmd *cmd, LOCKMODE lockmode);
 static void ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode);
 static void ATPostAlterTypeParse(char *cmd, List **wqueue, LOCKMODE lockmode);
 static void change_owner_recurse_to_sequences(Oid relationOid,
@@ -1433,7 +1433,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
 				def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
-				typenameTypeIdModColl(NULL, def->typeName, &defTypeId, &deftypmod, &defCollId);
+				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
 				if (defTypeId != attribute->atttypid ||
 					deftypmod != attribute->atttypmod)
 					ereport(ERROR,
@@ -1443,6 +1443,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 							 errdetail("%s versus %s",
 									   TypeNameToString(def->typeName),
 									   format_type_be(attribute->atttypid))));
+				defCollId = GetColumnDefCollation(NULL, def, defTypeId);
 				if (defCollId != attribute->attcollation)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
@@ -1478,14 +1479,16 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				def = makeNode(ColumnDef);
 				def->colname = pstrdup(attributeName);
 				def->typeName = makeTypeNameFromOid(attribute->atttypid,
-													attribute->atttypmod,
-													attribute->attcollation);
+													attribute->atttypmod);
 				def->inhcount = 1;
 				def->is_local = false;
 				def->is_not_null = attribute->attnotnull;
+				def->is_from_type = false;
 				def->storage = attribute->attstorage;
 				def->raw_default = NULL;
 				def->cooked_default = NULL;
+				def->collClause = NULL;
+				def->collOid = attribute->attcollation;
 				def->constraints = NIL;
 				inhSchema = lappend(inhSchema, def);
 				newattno[parent_attno - 1] = ++child_attno;
@@ -1616,8 +1619,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				   (errmsg("merging column \"%s\" with inherited definition",
 						   attributeName)));
 				def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
-				typenameTypeIdModColl(NULL, def->typeName, &defTypeId, &deftypmod, &defcollid);
-				typenameTypeIdModColl(NULL, newdef->typeName, &newTypeId, &newtypmod, &newcollid);
+				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newTypeId, &newtypmod);
 				if (defTypeId != newTypeId || deftypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
@@ -1626,6 +1629,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 							 errdetail("%s versus %s",
 									   TypeNameToString(def->typeName),
 									   TypeNameToString(newdef->typeName))));
+				defcollid = GetColumnDefCollation(NULL, def, defTypeId);
+				newcollid = GetColumnDefCollation(NULL, newdef, newTypeId);
 				if (defcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
@@ -3092,7 +3097,7 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 								 cmd->missing_ok, lockmode);
 			break;
 		case AT_AlterColumnType:		/* ALTER COLUMN TYPE */
-			ATExecAlterColumnType(tab, rel, cmd->name, (TypeName *) cmd->def, lockmode);
+			ATExecAlterColumnType(tab, rel, cmd, lockmode);
 			break;
 		case AT_ChangeOwner:	/* ALTER OWNER */
 			ATExecChangeOwner(RelationGetRelid(rel),
@@ -4129,13 +4134,14 @@ ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
 			Oid			ccollid;
 
 			/* Child column must match by type */
-			typenameTypeIdModColl(NULL, colDef->typeName, &ctypeId, &ctypmod, &ccollid);
+			typenameTypeIdAndMod(NULL, colDef->typeName, &ctypeId, &ctypmod);
 			if (ctypeId != childatt->atttypid ||
 				ctypmod != childatt->atttypmod)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
 						 errmsg("child table \"%s\" has different type for column \"%s\"",
 							RelationGetRelationName(rel), colDef->colname)));
+			ccollid = GetColumnDefCollation(NULL, colDef, ctypeId);
 			if (ccollid != childatt->attcollation)
 				ereport(ERROR,
 						(errcode(ERRCODE_COLLATION_MISMATCH),
@@ -4201,9 +4207,10 @@ ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
 							MaxHeapAttributeNumber)));
 	}
 
-	typeTuple = typenameType(NULL, colDef->typeName, &typmod, &collOid);
+	typeTuple = typenameType(NULL, colDef->typeName, &typmod);
 	tform = (Form_pg_type) GETSTRUCT(typeTuple);
 	typeOid = HeapTupleGetOid(typeTuple);
+	collOid = GetColumnDefCollation(NULL, colDef, typeOid);
 
 	/* make sure datatype is legal for a column */
 	CheckAttributeType(colDef->colname, typeOid, collOid, false);
@@ -4413,7 +4420,7 @@ ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd, LOC
 		ColumnDef  *cdef = makeNode(ColumnDef);
 
 		cdef->colname = pstrdup("oid");
-		cdef->typeName = makeTypeNameFromOid(OIDOID, -1, InvalidOid);
+		cdef->typeName = makeTypeNameFromOid(OIDOID, -1);
 		cdef->inhcount = 0;
 		cdef->is_local = true;
 		cdef->is_not_null = true;
@@ -6471,14 +6478,15 @@ ATPrepAlterColumnType(List **wqueue,
 					  AlterTableCmd *cmd, LOCKMODE lockmode)
 {
 	char	   *colName = cmd->name;
-	TypeName   *typeName = (TypeName *) cmd->def;
+	ColumnDef  *def = (ColumnDef *) cmd->def;
+	TypeName   *typeName = def->typeName;
+	Node	   *transform = def->raw_default;
 	HeapTuple	tuple;
 	Form_pg_attribute attTup;
 	AttrNumber	attnum;
 	Oid			targettype;
 	int32		targettypmod;
 	Oid			targetcollid;
-	Node	   *transform;
 	NewColumnValue *newval;
 	ParseState *pstate = make_parsestate(NULL);
 
@@ -6512,7 +6520,10 @@ ATPrepAlterColumnType(List **wqueue,
 						colName)));
 
 	/* Look up the target type */
-	typenameTypeIdModColl(NULL, typeName, &targettype, &targettypmod, &targetcollid);
+	typenameTypeIdAndMod(NULL, typeName, &targettype, &targettypmod);
+
+	/* And the collation */
+	targetcollid = GetColumnDefCollation(NULL, def, targettype);
 
 	/* make sure datatype is legal for a column */
 	CheckAttributeType(colName, targettype, targetcollid, false);
@@ -6527,7 +6538,7 @@ ATPrepAlterColumnType(List **wqueue,
 		 * because we need the expression to be parsed against the original table
 		 * rowtype.
 		 */
-		if (cmd->transform)
+		if (transform)
 		{
 			RangeTblEntry *rte;
 
@@ -6539,7 +6550,7 @@ ATPrepAlterColumnType(List **wqueue,
 												true);
 			addRTEtoQuery(pstate, rte, false, true, true);
 
-			transform = transformExpr(pstate, cmd->transform);
+			transform = transformExpr(pstate, transform);
 
 			/* It can't return a set */
 			if (expression_returns_set(transform))
@@ -6592,16 +6603,13 @@ ATPrepAlterColumnType(List **wqueue,
 		if (ATColumnChangeRequiresRewrite(transform, attnum))
 			tab->rewrite = true;
 	}
-	else if (tab->relkind == RELKIND_FOREIGN_TABLE)
-	{
-		if (cmd->transform)
-			ereport(ERROR,
-					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-					 errmsg("ALTER TYPE USING is not supported on foreign tables")));
-	}
+	else if (transform)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("ALTER TYPE USING is only supported on plain tables")));
 
-	if (tab->relkind == RELKIND_COMPOSITE_TYPE
-		|| tab->relkind == RELKIND_FOREIGN_TABLE)
+	if (tab->relkind == RELKIND_COMPOSITE_TYPE ||
+		tab->relkind == RELKIND_FOREIGN_TABLE)
 	{
 		/*
 		 * For composite types, do this check now.  Tables will check
@@ -6667,8 +6675,11 @@ ATColumnChangeRequiresRewrite(Node *expr, AttrNumber varattno)
 
 static void
 ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
-					  const char *colName, TypeName *typeName, LOCKMODE lockmode)
+					  AlterTableCmd *cmd, LOCKMODE lockmode)
 {
+	char	   *colName = cmd->name;
+	ColumnDef  *def = (ColumnDef *) cmd->def;
+	TypeName   *typeName = def->typeName;
 	HeapTuple	heapTup;
 	Form_pg_attribute attTup;
 	AttrNumber	attnum;
@@ -6705,9 +6716,11 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 						colName)));
 
 	/* Look up the target type (should not fail, since prep found it) */
-	typeTuple = typenameType(NULL, typeName, &targettypmod, &targetcollid);
+	typeTuple = typenameType(NULL, typeName, &targettypmod);
 	tform = (Form_pg_type) GETSTRUCT(typeTuple);
 	targettype = HeapTupleGetOid(typeTuple);
+	/* And the collation */
+	targetcollid = GetColumnDefCollation(NULL, def, targettype);
 
 	/*
 	 * If there is a default expression for the column, get it and ensure we
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
index be1f1d791fd..3513256b9a5 100644
--- a/src/backend/commands/typecmds.c
+++ b/src/backend/commands/typecmds.c
@@ -292,7 +292,7 @@ DefineType(List *names, List *parameters)
 		Type		likeType;
 		Form_pg_type likeForm;
 
-		likeType = typenameType(NULL, defGetTypeName(likeTypeEl), NULL, NULL);
+		likeType = typenameType(NULL, defGetTypeName(likeTypeEl), NULL);
 		likeForm = (Form_pg_type) GETSTRUCT(likeType);
 		internalLength = likeForm->typlen;
 		byValue = likeForm->typbyval;
@@ -649,7 +649,7 @@ RemoveTypes(DropStmt *drop)
 		typename = makeTypeNameFromNameList(names);
 
 		/* Use LookupTypeName here so that shell types can be removed. */
-		tup = LookupTypeName(NULL, typename, NULL, NULL);
+		tup = LookupTypeName(NULL, typename, NULL);
 		if (tup == NULL)
 		{
 			if (!drop->missing_ok)
@@ -774,6 +774,7 @@ DefineDomain(CreateDomainStmt *stmt)
 	Oid			basetypeoid;
 	Oid			domainoid;
 	Oid			old_type_oid;
+	Oid			domaincoll;
 	Form_pg_type baseType;
 	int32		basetypeMod;
 	Oid			baseColl;
@@ -807,7 +808,7 @@ DefineDomain(CreateDomainStmt *stmt)
 	/*
 	 * Look up the base type.
 	 */
-	typeTup = typenameType(NULL, stmt->typeName, &basetypeMod, &baseColl);
+	typeTup = typenameType(NULL, stmt->typeName, &basetypeMod);
 	baseType = (Form_pg_type) GETSTRUCT(typeTup);
 	basetypeoid = HeapTupleGetOid(typeTup);
 
@@ -825,6 +826,22 @@ DefineDomain(CreateDomainStmt *stmt)
 				 errmsg("\"%s\" is not a valid base type for a domain",
 						TypeNameToString(stmt->typeName))));
 
+	/*
+	 * Identify the collation if any
+	 */
+	baseColl = baseType->typcollation;
+	if (stmt->collClause)
+		domaincoll = get_collation_oid(stmt->collClause->collnames, false);
+	else
+		domaincoll = baseColl;
+
+	/* Complain if COLLATE is applied to an uncollatable type */
+	if (OidIsValid(domaincoll) && !OidIsValid(baseColl))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("collations are not supported by type %s",
+						format_type_be(basetypeoid))));
+
 	/* passed by value */
 	byValue = baseType->typbyval;
 
@@ -1051,7 +1068,7 @@ DefineDomain(CreateDomainStmt *stmt)
 				   basetypeMod, /* typeMod value */
 				   typNDims,	/* Array dimensions for base type */
 				   typNotNull,	/* Type NOT NULL */
-				   baseColl);
+				   domaincoll);
 
 	/*
 	 * Process constraints which refer to the domain ID returned by TypeCreate
@@ -2629,7 +2646,7 @@ AlterTypeOwner(List *names, Oid newOwnerId)
 	typename = makeTypeNameFromNameList(names);
 
 	/* Use LookupTypeName here so that shell types can be processed */
-	tup = LookupTypeName(NULL, typename, NULL, NULL);
+	tup = LookupTypeName(NULL, typename, NULL);
 	if (tup == NULL)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 5576ea259f4..794a56e84de 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -120,14 +120,23 @@ DefineVirtualRelation(const RangeVar *relation, List *tlist, bool replace)
 
 			def->colname = pstrdup(tle->resname);
 			def->typeName = makeTypeNameFromOid(exprType((Node *) tle->expr),
-												exprTypmod((Node *) tle->expr),
-												exprCollation((Node *) tle->expr));
+												exprTypmod((Node *) tle->expr));
 			def->inhcount = 0;
 			def->is_local = true;
 			def->is_not_null = false;
+			def->is_from_type = false;
 			def->storage = 0;
 			def->raw_default = NULL;
 			def->cooked_default = NULL;
+			def->collClause = NULL;
+			/*
+			 * XXX Temporary kluge to make regression tests pass.  We should
+			 * be able to trust the result of exprCollation more than this.
+			 */
+			if (type_is_collatable(exprType((Node *) tle->expr)))
+				def->collOid = exprCollation((Node *) tle->expr);
+			else
+				def->collOid = InvalidOid;
 			def->constraints = NIL;
 
 			attrList = lappend(attrList, def);
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 86a16783f71..b948af604d8 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2183,8 +2183,6 @@ _copyTypeName(TypeName *from)
 	COPY_NODE_FIELD(typmods);
 	COPY_SCALAR_FIELD(typemod);
 	COPY_NODE_FIELD(arrayBounds);
-	COPY_NODE_FIELD(collnames);
-	COPY_SCALAR_FIELD(collOid);
 	COPY_LOCATION_FIELD(location);
 
 	return newnode;
@@ -2295,9 +2293,12 @@ _copyColumnDef(ColumnDef *from)
 	COPY_SCALAR_FIELD(inhcount);
 	COPY_SCALAR_FIELD(is_local);
 	COPY_SCALAR_FIELD(is_not_null);
+	COPY_SCALAR_FIELD(is_from_type);
 	COPY_SCALAR_FIELD(storage);
 	COPY_NODE_FIELD(raw_default);
 	COPY_NODE_FIELD(cooked_default);
+	COPY_NODE_FIELD(collClause);
+	COPY_SCALAR_FIELD(collOid);
 	COPY_NODE_FIELD(constraints);
 
 	return newnode;
@@ -2515,7 +2516,6 @@ _copyAlterTableCmd(AlterTableCmd *from)
 	COPY_SCALAR_FIELD(subtype);
 	COPY_STRING_FIELD(name);
 	COPY_NODE_FIELD(def);
-	COPY_NODE_FIELD(transform);
 	COPY_SCALAR_FIELD(behavior);
 	COPY_SCALAR_FIELD(missing_ok);
 
@@ -3063,6 +3063,7 @@ _copyCreateDomainStmt(CreateDomainStmt *from)
 
 	COPY_NODE_FIELD(domainname);
 	COPY_NODE_FIELD(typeName);
+	COPY_NODE_FIELD(collClause);
 	COPY_NODE_FIELD(constraints);
 
 	return newnode;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index c234416cf53..c8ee4744364 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1007,7 +1007,6 @@ _equalAlterTableCmd(AlterTableCmd *a, AlterTableCmd *b)
 	COMPARE_SCALAR_FIELD(subtype);
 	COMPARE_STRING_FIELD(name);
 	COMPARE_NODE_FIELD(def);
-	COMPARE_NODE_FIELD(transform);
 	COMPARE_SCALAR_FIELD(behavior);
 	COMPARE_SCALAR_FIELD(missing_ok);
 
@@ -1461,6 +1460,7 @@ _equalCreateDomainStmt(CreateDomainStmt *a, CreateDomainStmt *b)
 {
 	COMPARE_NODE_FIELD(domainname);
 	COMPARE_NODE_FIELD(typeName);
+	COMPARE_NODE_FIELD(collClause);
 	COMPARE_NODE_FIELD(constraints);
 
 	return true;
@@ -2130,8 +2130,6 @@ _equalTypeName(TypeName *a, TypeName *b)
 	COMPARE_NODE_FIELD(typmods);
 	COMPARE_SCALAR_FIELD(typemod);
 	COMPARE_NODE_FIELD(arrayBounds);
-	COMPARE_NODE_FIELD(collnames);
-	COMPARE_SCALAR_FIELD(collOid);
 	COMPARE_LOCATION_FIELD(location);
 
 	return true;
@@ -2226,9 +2224,12 @@ _equalColumnDef(ColumnDef *a, ColumnDef *b)
 	COMPARE_SCALAR_FIELD(inhcount);
 	COMPARE_SCALAR_FIELD(is_local);
 	COMPARE_SCALAR_FIELD(is_not_null);
+	COMPARE_SCALAR_FIELD(is_from_type);
 	COMPARE_SCALAR_FIELD(storage);
 	COMPARE_NODE_FIELD(raw_default);
 	COMPARE_NODE_FIELD(cooked_default);
+	COMPARE_NODE_FIELD(collClause);
+	COMPARE_SCALAR_FIELD(collOid);
 	COMPARE_NODE_FIELD(constraints);
 
 	return true;
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index 0225f19382a..d9f16452383 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -427,16 +427,15 @@ makeTypeNameFromNameList(List *names)
 
 /*
  * makeTypeNameFromOid -
- *	build a TypeName node to represent a type already known by OID/typmod/collation.
+ *	build a TypeName node to represent a type already known by OID/typmod.
  */
 TypeName *
-makeTypeNameFromOid(Oid typeOid, int32 typmod, Oid collOid)
+makeTypeNameFromOid(Oid typeOid, int32 typmod)
 {
 	TypeName   *n = makeNode(TypeName);
 
 	n->typeOid = typeOid;
 	n->typemod = typmod;
-	n->collOid = collOid;
 	n->location = -1;
 	return n;
 }
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 4aae2b33a6d..06fd7ff818e 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2067,9 +2067,12 @@ _outColumnDef(StringInfo str, ColumnDef *node)
 	WRITE_INT_FIELD(inhcount);
 	WRITE_BOOL_FIELD(is_local);
 	WRITE_BOOL_FIELD(is_not_null);
+	WRITE_BOOL_FIELD(is_from_type);
 	WRITE_INT_FIELD(storage);
 	WRITE_NODE_FIELD(raw_default);
 	WRITE_NODE_FIELD(cooked_default);
+	WRITE_NODE_FIELD(collClause);
+	WRITE_OID_FIELD(collOid);
 	WRITE_NODE_FIELD(constraints);
 }
 
@@ -2085,8 +2088,6 @@ _outTypeName(StringInfo str, TypeName *node)
 	WRITE_NODE_FIELD(typmods);
 	WRITE_INT_FIELD(typemod);
 	WRITE_NODE_FIELD(arrayBounds);
-	WRITE_NODE_FIELD(collnames);
-	WRITE_OID_FIELD(collOid);
 	WRITE_LOCATION_FIELD(location);
 }
 
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 5b96b5b0df5..373d2adc71c 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -132,6 +132,9 @@ static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args,
 static List *mergeTableFuncParameters(List *func_args, List *columns);
 static TypeName *TableFuncTypeName(List *columns);
 static RangeVar *makeRangeVarFromAnyName(List *names, int position, core_yyscan_t yyscanner);
+static void SplitColQualList(List *qualList,
+							 List **constraintList, CollateClause **collClause,
+							 core_yyscan_t yyscanner);
 
 %}
 
@@ -221,7 +224,7 @@ static RangeVar *makeRangeVarFromAnyName(List *names, int position, core_yyscan_
 %type <node>	alter_column_default opclass_item opclass_drop alter_using
 %type <ival>	add_drop opt_asc_desc opt_nulls_order
 
-%type <node>	alter_table_cmd alter_type_cmd
+%type <node>	alter_table_cmd alter_type_cmd opt_collate_clause
 %type <list>	alter_table_cmds alter_type_cmds
 
 %type <dbehavior>	opt_drop_behavior
@@ -400,8 +403,7 @@ static RangeVar *makeRangeVarFromAnyName(List *names, int position, core_yyscan_
 %type <list>	copy_generic_opt_list copy_generic_opt_arg_list
 %type <list>	copy_options
 
-%type <typnam>	Typename SimpleTypename SimpleTypenameWithoutCollation
-				ConstTypename
+%type <typnam>	Typename SimpleTypename ConstTypename
 				GenericType Numeric opt_float
 				Character ConstCharacter
 				CharacterWithLength CharacterWithoutLength
@@ -619,6 +621,7 @@ static RangeVar *makeRangeVarFromAnyName(List *names, int position, core_yyscan_
 %left		'^'
 /* Unary Operators */
 %left		AT ZONE			/* sets precedence for AT TIME ZONE */
+%left		COLLATE
 %right		UMINUS
 %left		'[' ']'
 %left		'(' ')'
@@ -1746,13 +1749,17 @@ alter_table_cmd:
 			 * ALTER TABLE <name> ALTER [COLUMN] <colname> [SET DATA] TYPE <typename>
 			 *		[ USING <expression> ]
 			 */
-			| ALTER opt_column ColId opt_set_data TYPE_P Typename alter_using
+			| ALTER opt_column ColId opt_set_data TYPE_P Typename opt_collate_clause alter_using
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
+					ColumnDef *def = makeNode(ColumnDef);
 					n->subtype = AT_AlterColumnType;
 					n->name = $3;
-					n->def = (Node *) $6;
-					n->transform = $7;
+					n->def = (Node *) def;
+					/* We only use these three fields of the ColumnDef node */
+					def->typeName = $6;
+					def->collClause = (CollateClause *) $7;
+					def->raw_default = $8;
 					$$ = (Node *)n;
 				}
 			/* ALTER TABLE <name> ADD CONSTRAINT ... */
@@ -1981,6 +1988,19 @@ opt_drop_behavior:
 			| /* EMPTY */				{ $$ = DROP_RESTRICT; /* default */ }
 		;
 
+opt_collate_clause:
+			COLLATE any_name
+				{
+					CollateClause *n = makeNode(CollateClause);
+					n->arg = NULL;
+					n->collnames = $2;
+					n->collOid = InvalidOid;
+					n->location = @1;
+					$$ = (Node *) n;
+				}
+			| /* EMPTY */				{ $$ = NULL; }
+		;
+
 alter_using:
 			USING a_expr				{ $$ = $2; }
 			| /* EMPTY */				{ $$ = NULL; }
@@ -2077,13 +2097,18 @@ alter_type_cmd:
 					$$ = (Node *)n;
 				}
 			/* ALTER TYPE <name> ALTER ATTRIBUTE <attname> [SET DATA] TYPE <typename> [RESTRICT|CASCADE] */
-			| ALTER ATTRIBUTE ColId opt_set_data TYPE_P Typename opt_drop_behavior
+			| ALTER ATTRIBUTE ColId opt_set_data TYPE_P Typename opt_collate_clause opt_drop_behavior
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
+					ColumnDef *def = makeNode(ColumnDef);
 					n->subtype = AT_AlterColumnType;
 					n->name = $3;
-					n->def = (Node *) $6;
-					n->behavior = $7;
+					n->def = (Node *) def;
+					n->behavior = $8;
+					/* We only use these three fields of the ColumnDef node */
+					def->typeName = $6;
+					def->collClause = (CollateClause *) $7;
+					def->raw_default = NULL;
 					$$ = (Node *)n;
 				}
 		;
@@ -2454,8 +2479,16 @@ columnDef:	ColId Typename ColQualList
 					ColumnDef *n = makeNode(ColumnDef);
 					n->colname = $1;
 					n->typeName = $2;
-					n->constraints = $3;
+					n->inhcount = 0;
 					n->is_local = true;
+					n->is_not_null = false;
+					n->is_from_type = false;
+					n->storage = 0;
+					n->raw_default = NULL;
+					n->cooked_default = NULL;
+					n->collOid = InvalidOid;
+					SplitColQualList($3, &n->constraints, &n->collClause,
+									 yyscanner);
 					$$ = (Node *)n;
 				}
 		;
@@ -2464,8 +2497,17 @@ columnOptions:	ColId WITH OPTIONS ColQualList
 				{
 					ColumnDef *n = makeNode(ColumnDef);
 					n->colname = $1;
-					n->constraints = $4;
+					n->typeName = NULL;
+					n->inhcount = 0;
 					n->is_local = true;
+					n->is_not_null = false;
+					n->is_from_type = false;
+					n->storage = 0;
+					n->raw_default = NULL;
+					n->cooked_default = NULL;
+					n->collOid = InvalidOid;
+					SplitColQualList($4, &n->constraints, &n->collClause,
+									 yyscanner);
 					$$ = (Node *)n;
 				}
 		;
@@ -2486,6 +2528,20 @@ ColConstraint:
 				}
 			| ColConstraintElem						{ $$ = $1; }
 			| ConstraintAttr						{ $$ = $1; }
+			| COLLATE any_name
+				{
+					/*
+					 * Note: the CollateClause is momentarily included in
+					 * the list built by ColQualList, but we split it out
+					 * again in SplitColQualList.
+					 */
+					CollateClause *n = makeNode(CollateClause);
+					n->arg = NULL;
+					n->collnames = $2;
+					n->collOid = InvalidOid;
+					n->location = @1;
+					$$ = (Node *) n;
+				}
 		;
 
 /* DEFAULT NULL is already the default for Postgres.
@@ -2973,8 +3029,12 @@ CreateAsElement:
 					n->inhcount = 0;
 					n->is_local = true;
 					n->is_not_null = false;
+					n->is_from_type = false;
+					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->collClause = NULL;
+					n->collOid = InvalidOid;
 					n->constraints = NIL;
 					$$ = (Node *)n;
 				}
@@ -6577,7 +6637,7 @@ opt_column: COLUMN									{ $$ = COLUMN; }
 			| /*EMPTY*/								{ $$ = 0; }
 		;
 
-opt_set_data: SET DATA_P									{ $$ = 1; }
+opt_set_data: SET DATA_P							{ $$ = 1; }
 			| /*EMPTY*/								{ $$ = 0; }
 		;
 
@@ -7443,7 +7503,8 @@ CreateDomainStmt:
 					CreateDomainStmt *n = makeNode(CreateDomainStmt);
 					n->domainname = $3;
 					n->typeName = $5;
-					n->constraints = $6;
+					SplitColQualList($6, &n->constraints, &n->collClause,
+									 yyscanner);
 					$$ = (Node *)n;
 				}
 		;
@@ -9084,13 +9145,21 @@ TableFuncElementList:
 				}
 		;
 
-TableFuncElement:	ColId Typename
+TableFuncElement:	ColId Typename opt_collate_clause
 				{
 					ColumnDef *n = makeNode(ColumnDef);
 					n->colname = $1;
 					n->typeName = $2;
-					n->constraints = NIL;
+					n->inhcount = 0;
 					n->is_local = true;
+					n->is_not_null = false;
+					n->is_from_type = false;
+					n->storage = 0;
+					n->raw_default = NULL;
+					n->cooked_default = NULL;
+					n->collClause = (CollateClause *) $3;
+					n->collOid = InvalidOid;
+					n->constraints = NIL;
 					$$ = (Node *)n;
 				}
 		;
@@ -9151,13 +9220,6 @@ opt_array_bounds:
 		;
 
 SimpleTypename:
-			SimpleTypenameWithoutCollation opt_collate
-			{
-				$$ = $1;
-				$$->collnames = $2;
-			}
-
-SimpleTypenameWithoutCollation:
 			GenericType								{ $$ = $1; }
 			| Numeric								{ $$ = $1; }
 			| Bit									{ $$ = $1; }
@@ -9625,6 +9687,14 @@ interval_second:
 a_expr:		c_expr									{ $$ = $1; }
 			| a_expr TYPECAST Typename
 					{ $$ = makeTypeCast($1, $3, @2); }
+			| a_expr COLLATE any_name
+				{
+					CollateClause *n = makeNode(CollateClause);
+					n->arg = (Expr *) $1;
+					n->collnames = $3;
+					n->location = @2;
+					$$ = (Node *) n;
+				}
 			| a_expr AT TIME ZONE a_expr
 				{
 					FuncCall *n = makeNode(FuncCall);
@@ -10193,14 +10263,6 @@ c_expr:		columnref								{ $$ = $1; }
 					r->location = @1;
 					$$ = (Node *)r;
 				}
-			| c_expr COLLATE any_name
-				{
-					CollateClause *n = makeNode(CollateClause);
-					n->arg = (Expr *) $1;
-					n->collnames = $3;
-					n->location = @2;
-					$$ = (Node *)n;
-				}
 		;
 
 /*
@@ -12678,15 +12740,6 @@ makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args,
 	return (Node *) x;
 }
 
-/* parser_init()
- * Initialize to parse one query string
- */
-void
-parser_init(base_yy_extra_type *yyext)
-{
-	yyext->parsetree = NIL;		/* in case grammar forgets to set it */
-}
-
 /*
  * Merge the input and output parameters of a table function.
  */
@@ -12774,6 +12827,57 @@ makeRangeVarFromAnyName(List *names, int position, core_yyscan_t yyscanner)
 	return r;
 }
 
+/* Separate Constraint nodes from COLLATE clauses in a ColQualList */
+static void
+SplitColQualList(List *qualList,
+				 List **constraintList, CollateClause **collClause,
+				 core_yyscan_t yyscanner)
+{
+	ListCell   *cell;
+	ListCell   *prev;
+	ListCell   *next;
+
+	*collClause = NULL;
+	prev = NULL;
+	for (cell = list_head(qualList); cell; cell = next)
+	{
+		Node   *n = (Node *) lfirst(cell);
+
+		next = lnext(cell);
+		if (IsA(n, Constraint))
+		{
+			/* keep it in list */
+			prev = cell;
+			continue;
+		}
+		if (IsA(n, CollateClause))
+		{
+			CollateClause *c = (CollateClause *) n;
+
+			if (*collClause)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("multiple COLLATE clauses not allowed"),
+						 parser_errposition(c->location)));
+			*collClause = c;
+		}
+		else
+			elog(ERROR, "unexpected node type %d", (int) n->type);
+		/* remove non-Constraint nodes from qualList */
+		qualList = list_delete_cell(qualList, cell, prev);
+	}
+	*constraintList = qualList;
+}
+
+/* parser_init()
+ * Initialize to parse one query string
+ */
+void
+parser_init(base_yy_extra_type *yyext)
+{
+	yyext->parsetree = NIL;		/* in case grammar forgets to set it */
+}
+
 /*
  * Must undefine this stuff before including scan.c, since it has different
  * definitions for these macros.
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index ae565325928..7a4f8cc2497 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -147,12 +147,6 @@ transformExpr(ParseState *pstate, Node *expr)
 			{
 				TypeCast   *tc = (TypeCast *) expr;
 
-				if (tc->typeName->collnames)
-					ereport(ERROR,
-							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("COLLATE clause not allowed in cast target"),
-							 parser_errposition(pstate, tc->typeName->location)));
-
 				/*
 				 * If the subject of the typecast is an ARRAY[] construct and
 				 * the target type is an array type, we invoke
@@ -2116,13 +2110,16 @@ transformCollateClause(ParseState *pstate, CollateClause *c)
 	newc->arg = (Expr *) transformExpr(pstate, (Node *) c->arg);
 
 	argtype = exprType((Node *) newc->arg);
-	/* The unknown type is not collatable, but coerce_type() takes
-	 * care of it separately, so we'll let it go here. */
+	/*
+	 * The unknown type is not collatable, but coerce_type() takes
+	 * care of it separately, so we'll let it go here.
+	 */
 	if (!type_is_collatable(argtype) && argtype != UNKNOWNOID)
 		ereport(ERROR,
-				(errcode(ERRCODE_SYNTAX_ERROR),
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
 				 errmsg("collations are not supported by type %s",
-						format_type_be(argtype))));
+						format_type_be(argtype)),
+				 parser_errposition(pstate, c->location)));
 
 	newc->collOid = LookupCollation(pstate, c->collnames, c->location);
 	newc->collnames = c->collnames;
diff --git a/src/backend/parser/parse_func.c b/src/backend/parser/parse_func.c
index 0af9cbd92b3..a2d6c598104 100644
--- a/src/backend/parser/parse_func.c
+++ b/src/backend/parser/parse_func.c
@@ -1313,7 +1313,7 @@ FuncNameAsType(List *funcname)
 	Oid			result;
 	Type		typtup;
 
-	typtup = LookupTypeName(NULL, makeTypeNameFromNameList(funcname), NULL, NULL);
+	typtup = LookupTypeName(NULL, makeTypeNameFromNameList(funcname), NULL);
 	if (typtup == NULL)
 		return InvalidOid;
 
@@ -1500,7 +1500,7 @@ LookupTypeNameOid(const TypeName *typename)
 	Oid			result;
 	Type		typtup;
 
-	typtup = LookupTypeName(NULL, typename, NULL, NULL);
+	typtup = LookupTypeName(NULL, typename, NULL);
 	if (typtup == NULL)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index c7000b99153..488b1425a35 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -1169,7 +1169,8 @@ addRangeTableEntryForFunction(ParseState *pstate,
 						 errmsg("column \"%s\" cannot be declared SETOF",
 								attrname),
 						 parser_errposition(pstate, n->typeName->location)));
-			typenameTypeIdModColl(pstate, n->typeName, &attrtype, &attrtypmod, &attrcollation);
+			typenameTypeIdAndMod(pstate, n->typeName, &attrtype, &attrtypmod);
+			attrcollation = GetColumnDefCollation(pstate, n, attrtype);
 			eref->colnames = lappend(eref->colnames, makeString(attrname));
 			rte->funccoltypes = lappend_oid(rte->funccoltypes, attrtype);
 			rte->funccoltypmods = lappend_int(rte->funccoltypmods, attrtypmod);
diff --git a/src/backend/parser/parse_type.c b/src/backend/parser/parse_type.c
index 20cb47e712f..2ba9bf51816 100644
--- a/src/backend/parser/parse_type.c
+++ b/src/backend/parser/parse_type.c
@@ -29,8 +29,6 @@
 
 static int32 typenameTypeMod(ParseState *pstate, const TypeName *typeName,
 				Type typ);
-static Oid typenameCollation(ParseState *pstate, const TypeName *typeName,
-				Type typ);
 
 
 /*
@@ -38,8 +36,7 @@ static Oid typenameCollation(ParseState *pstate, const TypeName *typeName,
  *		Given a TypeName object, lookup the pg_type syscache entry of the type.
  *		Returns NULL if no such type can be found.	If the type is found,
  *		the typmod value represented in the TypeName struct is computed and
- *		stored into *typmod_p, and the collation is looked up and stored into
- *      *colloid_p.
+ *		stored into *typmod_p.
  *
  * NB: on success, the caller must ReleaseSysCache the type tuple when done
  * with it.
@@ -54,18 +51,15 @@ static Oid typenameCollation(ParseState *pstate, const TypeName *typeName,
  * found but is a shell, and there is typmod decoration, an error will be
  * thrown --- this is intentional.
  *
- * colloid_p can also be null.
- *
  * pstate is only used for error location info, and may be NULL.
  */
 Type
 LookupTypeName(ParseState *pstate, const TypeName *typeName,
-			   int32 *typmod_p, Oid *collid_p)
+			   int32 *typmod_p)
 {
 	Oid			typoid;
 	HeapTuple	tup;
 	int32		typmod;
-	Oid			collid;
 
 	if (typeName->names == NIL)
 	{
@@ -180,28 +174,22 @@ LookupTypeName(ParseState *pstate, const TypeName *typeName,
 	if (typmod_p)
 		*typmod_p = typmod;
 
-	collid = typenameCollation(pstate, typeName, (Type) tup);
-
-	if (collid_p)
-		*collid_p = collid;
-
 	return (Type) tup;
 }
 
 /*
- * typenameType - given a TypeName, return a Type structure, typmod, and
- * collation
+ * typenameType - given a TypeName, return a Type structure and typmod
  *
  * This is equivalent to LookupTypeName, except that this will report
  * a suitable error message if the type cannot be found or is not defined.
  * Callers of this can therefore assume the result is a fully valid type.
  */
 Type
-typenameType(ParseState *pstate, const TypeName *typeName, int32 *typmod_p, Oid *collid_p)
+typenameType(ParseState *pstate, const TypeName *typeName, int32 *typmod_p)
 {
 	Type		tup;
 
-	tup = LookupTypeName(pstate, typeName, typmod_p, collid_p);
+	tup = LookupTypeName(pstate, typeName, typmod_p);
 	if (tup == NULL)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
@@ -229,7 +217,7 @@ typenameTypeId(ParseState *pstate, const TypeName *typeName)
 	Oid			typoid;
 	Type		tup;
 
-	tup = typenameType(pstate, typeName, NULL, NULL);
+	tup = typenameType(pstate, typeName, NULL);
 	typoid = HeapTupleGetOid(tup);
 	ReleaseSysCache(tup);
 
@@ -248,25 +236,7 @@ typenameTypeIdAndMod(ParseState *pstate, const TypeName *typeName,
 {
 	Type		tup;
 
-	tup = typenameType(pstate, typeName, typmod_p, NULL);
-	*typeid_p = HeapTupleGetOid(tup);
-	ReleaseSysCache(tup);
-}
-
-/*
- * typenameTypeIdModColl - given a TypeName, return the type's OID,
- * typmod, and collation
- *
- * This is equivalent to typenameType, but we only hand back the type OID,
- * typmod, and collation, not the syscache entry.
- */
-void
-typenameTypeIdModColl(ParseState *pstate, const TypeName *typeName,
-					  Oid *typeid_p, int32 *typmod_p, Oid *collid_p)
-{
-	Type		tup;
-
-	tup = typenameType(pstate, typeName, typmod_p, collid_p);
+	tup = typenameType(pstate, typeName, typmod_p);
 	*typeid_p = HeapTupleGetOid(tup);
 	ReleaseSysCache(tup);
 }
@@ -381,62 +351,6 @@ typenameTypeMod(ParseState *pstate, const TypeName *typeName, Type typ)
 }
 
 /*
- * typenameCollation - given a TypeName, return the collation OID
- *
- * This will throw an error if the TypeName includes a collation but
- * the data type does not support collations.
- *
- * The actual type OID represented by the TypeName must already have been
- * looked up, and is passed as "typ".
- *
- * pstate is only used for error location info, and may be NULL.
- */
-static Oid
-typenameCollation(ParseState *pstate, const TypeName *typeName, Type typ)
-{
-	Oid typcollation = ((Form_pg_type) GETSTRUCT(typ))->typcollation;
-
-	/* return prespecified collation OID if no collation name specified */
-	if (typeName->collnames == NIL)
-	{
-		if (typeName->collOid == InvalidOid)
-			return typcollation;
-		else
-			return typeName->collOid;
-	}
-
-	if (!OidIsValid(typcollation))
-		ereport(ERROR,
-				(errcode(ERRCODE_SYNTAX_ERROR),
-				 errmsg("collations are not supported by type %s",
-						format_type_be(HeapTupleGetOid(typ))),
-				 parser_errposition(pstate, typeName->location)));
-
-	return LookupCollation(pstate, typeName->collnames, typeName->location);
-}
-
-/*
- * LookupCollation
- *
- * Look up collation by name, return OID, with support for error
- * location.
- */
-Oid
-LookupCollation(ParseState *pstate, List *collnames, int location)
-{
-	Oid			colloid;
-	ParseCallbackState pcbstate;
-
-	setup_parser_errposition_callback(&pcbstate, pstate, location);
-
-	colloid = get_collation_oid(collnames, false);
-
-	cancel_parser_errposition_callback(&pcbstate);
-
-	return colloid;
-}
-
-/*
  * appendTypeNameToBuffer
  *		Append a string representing the name of a TypeName to a StringInfo.
  *		This is the shared guts of TypeNameToString and TypeNameListToString.
@@ -516,6 +430,72 @@ TypeNameListToString(List *typenames)
 	return string.data;
 }
 
+/*
+ * LookupCollation
+ *
+ * Look up collation by name, return OID, with support for error location.
+ */
+Oid
+LookupCollation(ParseState *pstate, List *collnames, int location)
+{
+	Oid			colloid;
+	ParseCallbackState pcbstate;
+
+	if (pstate)
+		setup_parser_errposition_callback(&pcbstate, pstate, location);
+
+	colloid = get_collation_oid(collnames, false);
+
+	if (pstate)
+		cancel_parser_errposition_callback(&pcbstate);
+
+	return colloid;
+}
+
+/*
+ * GetColumnDefCollation
+ *
+ * Get the collation to be used for a column being defined, given the
+ * ColumnDef node and the previously-determined column type OID.
+ *
+ * pstate is only used for error location purposes, and can be NULL.
+ */
+Oid
+GetColumnDefCollation(ParseState *pstate, ColumnDef *coldef, Oid typeOid)
+{
+	Oid			result;
+	Oid			typcollation = get_typcollation(typeOid);
+	int			location = -1;
+
+	if (coldef->collClause)
+	{
+		/* We have a raw COLLATE clause, so look up the collation */
+		location = coldef->collClause->location;
+		result = LookupCollation(pstate, coldef->collClause->collnames,
+								 location);
+	}
+	else if (OidIsValid(coldef->collOid))
+	{
+		/* Precooked collation spec, use that */
+		result = coldef->collOid;
+	}
+	else
+	{
+		/* Use the type's default collation if any */
+		result = typcollation;
+	}
+
+	/* Complain if COLLATE is applied to an uncollatable type */
+	if (OidIsValid(result) && !OidIsValid(typcollation))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("collations are not supported by type %s",
+						format_type_be(typeOid)),
+				 parser_errposition(pstate, location)));
+
+	return result;
+}
+
 /* return a Type structure, given a type id */
 /* NB: caller must ReleaseSysCache the type tuple when done with it */
 Type
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 61ce840a5e5..e876853af02 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -627,13 +627,16 @@ transformInhRelation(CreateStmtContext *cxt, InhRelation *inhRelation)
 		def = makeNode(ColumnDef);
 		def->colname = pstrdup(attributeName);
 		def->typeName = makeTypeNameFromOid(attribute->atttypid,
-											attribute->atttypmod,
-											attribute->attcollation);
+											attribute->atttypmod);
 		def->inhcount = 0;
 		def->is_local = true;
 		def->is_not_null = attribute->attnotnull;
+		def->is_from_type = false;
+		def->storage = 0;
 		def->raw_default = NULL;
 		def->cooked_default = NULL;
+		def->collClause = NULL;
+		def->collOid = attribute->attcollation;
 		def->constraints = NIL;
 
 		/*
@@ -822,7 +825,7 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 
 	AssertArg(ofTypename);
 
-	tuple = typenameType(NULL, ofTypename, NULL, NULL);
+	tuple = typenameType(NULL, ofTypename, NULL);
 	typ = (Form_pg_type) GETSTRUCT(tuple);
 	ofTypeId = HeapTupleGetOid(tuple);
 	ofTypename->typeOid = ofTypeId;		/* cached for later */
@@ -837,16 +840,24 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 	for (i = 0; i < tupdesc->natts; i++)
 	{
 		Form_pg_attribute attr = tupdesc->attrs[i];
-		ColumnDef  *n = makeNode(ColumnDef);
+		ColumnDef  *n;
 
 		if (attr->attisdropped)
 			continue;
 
+		n = makeNode(ColumnDef);
 		n->colname = pstrdup(NameStr(attr->attname));
-		n->typeName = makeTypeNameFromOid(attr->atttypid, attr->atttypmod, attr->attcollation);
-		n->constraints = NULL;
+		n->typeName = makeTypeNameFromOid(attr->atttypid, attr->atttypmod);
+		n->inhcount = 0;
 		n->is_local = true;
+		n->is_not_null = false;
 		n->is_from_type = true;
+		n->storage = 0;
+		n->raw_default = NULL;
+		n->cooked_default = NULL;
+		n->collClause = NULL;
+		n->collOid = attr->attcollation;
+		n->constraints = NIL;
 		cxt->columns = lappend(cxt->columns, n);
 	}
 	DecrTupleDescRefCount(tupdesc);
@@ -2445,9 +2456,28 @@ static void
 transformColumnType(CreateStmtContext *cxt, ColumnDef *column)
 {
 	/*
-	 * All we really need to do here is verify that the type is valid.
+	 * All we really need to do here is verify that the type is valid,
+	 * including any collation spec that might be present.
 	 */
-	Type		ctype = typenameType(cxt->pstate, column->typeName, NULL, NULL);
+	Type		ctype = typenameType(cxt->pstate, column->typeName, NULL);
+
+	if (column->collClause)
+	{
+		Form_pg_type typtup = (Form_pg_type) GETSTRUCT(ctype);
+		Oid		collOid;
+
+		collOid = LookupCollation(cxt->pstate,
+								  column->collClause->collnames,
+								  column->collClause->location);
+		/* Complain if COLLATE is applied to an uncollatable type */
+		if (!OidIsValid(typtup->typcollation))
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("collations are not supported by type %s",
+							format_type_be(HeapTupleGetOid(ctype))),
+					 parser_errposition(cxt->pstate,
+										column->collClause->location)));
+	}
 
 	ReleaseSysCache(ctype);
 }
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 025edf08386..7cbd0222cb2 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -5082,8 +5082,9 @@ get_rule_expr(Node *node, deparse_context *context,
 
 				if (!PRETTY_PAREN(context))
 					appendStringInfoChar(buf, '(');
-				get_rule_expr_paren(arg, context, false, node);
-				appendStringInfo(buf, " COLLATE %s", generate_collation_name(collate->collOid));
+				get_rule_expr_paren(arg, context, showimplicit, node);
+				appendStringInfo(buf, " COLLATE %s",
+								 generate_collation_name(collate->collOid));
 				if (!PRETTY_PAREN(context))
 					appendStringInfoChar(buf, ')');
 			}
diff --git a/src/include/nodes/makefuncs.h b/src/include/nodes/makefuncs.h
index 8b7db798b9c..6691b0dc77e 100644
--- a/src/include/nodes/makefuncs.h
+++ b/src/include/nodes/makefuncs.h
@@ -68,7 +68,7 @@ extern RangeVar *makeRangeVar(char *schemaname, char *relname, int location);
 
 extern TypeName *makeTypeName(char *typnam);
 extern TypeName *makeTypeNameFromNameList(List *names);
-extern TypeName *makeTypeNameFromOid(Oid typeOid, int32 typmod, Oid collOid);
+extern TypeName *makeTypeNameFromOid(Oid typeOid, int32 typmod);
 
 extern FuncExpr *makeFuncExpr(Oid funcid, Oid rettype,
 			 List *args, Oid collid, CoercionForm fformat);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 287e9f523ff..9d4515cb27f 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -168,8 +168,7 @@ typedef struct Query
  * specify the type by OID than by name.  If "names" is NIL then the
  * actual type OID is given by typeOid, otherwise typeOid is unused.
  * Similarly, if "typmods" is NIL then the actual typmod is expected to
- * be prespecified in typemod, otherwise typemod is unused.  Similarly
- * for collnames/collOid.
+ * be prespecified in typemod, otherwise typemod is unused.
  *
  * If pct_type is TRUE, then names is actually a field name and we look up
  * the type of that field.	Otherwise (the normal case), names is a type
@@ -185,8 +184,6 @@ typedef struct TypeName
 	List	   *typmods;		/* type modifier expression(s) */
 	int32		typemod;		/* prespecified type modifier */
 	List	   *arrayBounds;	/* array bounds */
-	List	   *collnames;		/* collation name */
-	Oid			collOid;		/* collation by OID */
 	int			location;		/* token location, or -1 if unknown */
 } TypeName;
 
@@ -468,6 +465,10 @@ typedef struct RangeFunction
  * how this ColumnDef node was created (by parsing, or by inheritance
  * from an existing relation).	We should never have both in the same node!
  *
+ * Similarly, we may have a COLLATE specification in either raw form
+ * (represented as a CollateClause with arg==NULL) or cooked form
+ * (the collation's OID).
+ *
  * The constraints list may contain a CONSTR_DEFAULT item in a raw
  * parsetree produced by gram.y, but transformCreateStmt will remove
  * the item and set raw_default instead.  CONSTR_DEFAULT items
@@ -485,6 +486,8 @@ typedef struct ColumnDef
 	char		storage;		/* attstorage setting, or 0 for default */
 	Node	   *raw_default;	/* default value (untransformed parse tree) */
 	Node	   *cooked_default; /* default value (transformed expr tree) */
+	CollateClause *collClause;	/* untransformed COLLATE spec, if any */
+	Oid			collOid;		/* collation OID (InvalidOid if not set) */
 	List	   *constraints;	/* other constraints on column */
 } ColumnDef;
 
@@ -1202,9 +1205,8 @@ typedef struct AlterTableCmd	/* one subcommand of an ALTER TABLE */
 	AlterTableType subtype;		/* Type of table alteration to apply */
 	char	   *name;			/* column, constraint, or trigger to act on,
 								 * or new owner or tablespace */
-	Node	   *def;			/* definition of new column, column type,
-								 * index, constraint, or parent table */
-	Node	   *transform;		/* transformation expr for ALTER TYPE */
+	Node	   *def;			/* definition of new column, index,
+								 * constraint, or parent table */
 	DropBehavior behavior;		/* RESTRICT or CASCADE for DROP cases */
 	bool		missing_ok;		/* skip error if missing? */
 	bool		validated;
@@ -1819,6 +1821,7 @@ typedef struct CreateDomainStmt
 	NodeTag		type;
 	List	   *domainname;		/* qualified name (list of Value strings) */
 	TypeName   *typeName;		/* the base type */
+	CollateClause *collClause;	/* untransformed COLLATE spec, if any */
 	List	   *constraints;	/* constraints (list of Constraint nodes) */
 } CreateDomainStmt;
 
diff --git a/src/include/parser/parse_type.h b/src/include/parser/parse_type.h
index 8621ab678d0..92c9ecba4ac 100644
--- a/src/include/parser/parse_type.h
+++ b/src/include/parser/parse_type.h
@@ -20,21 +20,19 @@
 typedef HeapTuple Type;
 
 extern Type LookupTypeName(ParseState *pstate, const TypeName *typeName,
-						   int32 *typmod_p, Oid *collid_p);
+			   int32 *typmod_p);
 extern Type typenameType(ParseState *pstate, const TypeName *typeName,
-						 int32 *typmod_p, Oid *collid_p);
-
-extern Oid LookupCollation(ParseState *pstate, List *collnames, int location);
-
+			 int32 *typmod_p);
 extern Oid typenameTypeId(ParseState *pstate, const TypeName *typeName);
 extern void typenameTypeIdAndMod(ParseState *pstate, const TypeName *typeName,
-								  Oid *typeid_p, int32 *typmod_p);
-extern void typenameTypeIdModColl(ParseState *pstate, const TypeName *typeName,
-								  Oid *typeid_p, int32 *typmod_p, Oid *collid_p);
+								 Oid *typeid_p, int32 *typmod_p);
 
 extern char *TypeNameToString(const TypeName *typeName);
 extern char *TypeNameListToString(List *typenames);
 
+extern Oid LookupCollation(ParseState *pstate, List *collnames, int location);
+extern Oid GetColumnDefCollation(ParseState *pstate, ColumnDef *coldef, Oid typeOid);
+
 extern Type typeidType(Oid id);
 
 extern Oid	typeTypeId(Type tp);
diff --git a/src/pl/plpgsql/src/pl_comp.c b/src/pl/plpgsql/src/pl_comp.c
index d2b3862ec72..41188a2369f 100644
--- a/src/pl/plpgsql/src/pl_comp.c
+++ b/src/pl/plpgsql/src/pl_comp.c
@@ -1565,7 +1565,7 @@ plpgsql_parse_wordtype(char *ident)
 	 * Word wasn't found in the namespace stack. Try to find a data type with
 	 * that name, but ignore shell types and complex types.
 	 */
-	typeTup = LookupTypeName(NULL, makeTypeName(ident), NULL, NULL);
+	typeTup = LookupTypeName(NULL, makeTypeName(ident), NULL);
 	if (typeTup)
 	{
 		Form_pg_type typeStruct = (Form_pg_type) GETSTRUCT(typeTup);
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index caa65b2f37f..5ad5de2f00b 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -20,21 +20,21 @@ CREATE TABLE collate_test_fail (
 );
 ERROR:  collation "ja_JP.eucjp" for current database encoding "UTF8" does not exist
 LINE 3:     b text COLLATE "ja_JP.eucjp"
-              ^
+                   ^
 CREATE TABLE collate_test_fail (
     a int,
     b text COLLATE "foo"
 );
 ERROR:  collation "foo" for current database encoding "UTF8" does not exist
 LINE 3:     b text COLLATE "foo"
-              ^
+                   ^
 CREATE TABLE collate_test_fail (
     a int COLLATE "en_US.utf8",
     b text
 );
 ERROR:  collations are not supported by type integer
 LINE 2:     a int COLLATE "en_US.utf8",
-              ^
+                  ^
 CREATE TABLE collate_test_like (
     LIKE collate_test1
 );
@@ -632,9 +632,9 @@ ERROR:  no collation was derived for column "b" with collatable type text
 HINT:  Use the COLLATE clause to set the collation explicitly.
 -- casting
 SELECT CAST('42' AS text COLLATE "C");
-ERROR:  COLLATE clause not allowed in cast target
+ERROR:  syntax error at or near "COLLATE"
 LINE 1: SELECT CAST('42' AS text COLLATE "C");
-                            ^
+                                 ^
 SELECT a, CAST(b AS varchar) FROM collate_test1 ORDER BY 2;
  a |  b  
 ---+-----
@@ -727,6 +727,8 @@ CREATE INDEX collate_test1_idx4 ON collate_test1 (a COLLATE "C"); -- fail
 ERROR:  collations are not supported by type integer
 CREATE INDEX collate_test1_idx5 ON collate_test1 ((a COLLATE "C")); -- fail
 ERROR:  collations are not supported by type integer
+LINE 1: ...ATE INDEX collate_test1_idx5 ON collate_test1 ((a COLLATE "C...
+                                                             ^
 SELECT relname, pg_get_indexdef(oid) FROM pg_class WHERE relname LIKE 'collate_test%_idx%';
       relname       |                                       pg_get_indexdef                                        
 --------------------+----------------------------------------------------------------------------------------------
diff --git a/src/test/regress/expected/foreign_data.out b/src/test/regress/expected/foreign_data.out
index 00730f25cb8..a7473349fdf 100644
--- a/src/test/regress/expected/foreign_data.out
+++ b/src/test/regress/expected/foreign_data.out
@@ -693,7 +693,7 @@ ERROR:  "ft1" is not a table or view
 ALTER FOREIGN TABLE ft1 ALTER COLUMN c6 SET NOT NULL;
 ALTER FOREIGN TABLE ft1 ALTER COLUMN c7 DROP NOT NULL;
 ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 TYPE char(10) using '0'; -- ERROR
-ERROR:  ALTER TYPE USING is not supported on foreign tables
+ERROR:  ALTER TYPE USING is only supported on plain tables
 ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 TYPE char(10);
 ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 SET DATA TYPE text;
 -- can't change the column type if it's used elsewhere