diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index ce5a5d741de..452a7f3f953 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -572,6 +572,10 @@ CheckAttributeNamesTypes(TupleDesc tupdesc, char relkind,
  * are reliably identifiable only within a session, since the identity info
  * may use a typmod that is only locally assigned.  The caller is expected
  * to know whether these cases are safe.)
+ *
+ * flags can also control the phrasing of the error messages.  If
+ * CHKATYPE_IS_PARTKEY is specified, "attname" should be a partition key
+ * column number as text, not a real column name.
  * --------------------------------
  */
 void
@@ -598,10 +602,19 @@ CheckAttributeType(const char *attname,
 		if (!((atttypid == ANYARRAYOID && (flags & CHKATYPE_ANYARRAY)) ||
 			  (atttypid == RECORDOID && (flags & CHKATYPE_ANYRECORD)) ||
 			  (atttypid == RECORDARRAYOID && (flags & CHKATYPE_ANYRECORD))))
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("column \"%s\" has pseudo-type %s",
-							attname, format_type_be(atttypid))));
+		{
+			if (flags & CHKATYPE_IS_PARTKEY)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				/* translator: first %s is an integer not a name */
+						 errmsg("partition key column %s has pseudo-type %s",
+								attname, format_type_be(atttypid))));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("column \"%s\" has pseudo-type %s",
+								attname, format_type_be(atttypid))));
+		}
 	}
 	else if (att_typtype == TYPTYPE_DOMAIN)
 	{
@@ -648,7 +661,7 @@ CheckAttributeType(const char *attname,
 			CheckAttributeType(NameStr(attr->attname),
 							   attr->atttypid, attr->attcollation,
 							   containing_rowtypes,
-							   flags);
+							   flags & ~CHKATYPE_IS_PARTKEY);
 		}
 
 		relation_close(relation, AccessShareLock);
@@ -679,11 +692,21 @@ CheckAttributeType(const char *attname,
 	 * useless, and it cannot be dumped, so we must disallow it.
 	 */
 	if (!OidIsValid(attcollation) && type_is_collatable(atttypid))
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-				 errmsg("no collation was derived for column \"%s\" with collatable type %s",
-						attname, format_type_be(atttypid)),
-				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	{
+		if (flags & CHKATYPE_IS_PARTKEY)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+			/* translator: first %s is an integer not a name */
+					 errmsg("no collation was derived for partition key column %s with collatable type %s",
+							attname, format_type_be(atttypid)),
+					 errhint("Use the COLLATE clause to set the collation explicitly.")));
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("no collation was derived for column \"%s\" with collatable type %s",
+							attname, format_type_be(atttypid)),
+					 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
 }
 
 /*
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index e8e004eef4d..53a8f1610a4 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4899,8 +4899,8 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
 
 			/*
 			 * Set all columns in the new slot to NULL initially, to ensure
-			 * columns added as part of the rewrite are initialized to
-			 * NULL. That is necessary as tab->newvals will not contain an
+			 * columns added as part of the rewrite are initialized to NULL.
+			 * That is necessary as tab->newvals will not contain an
 			 * expression for columns with a NULL default, e.g. when adding a
 			 * column without a default together with a column with a default
 			 * requiring an actual rewrite.
@@ -15096,11 +15096,23 @@ ComputePartitionAttrs(ParseState *pstate, Relation rel, List *partParams, AttrNu
 		{
 			/* Expression */
 			Node	   *expr = pelem->expr;
+			char		partattname[16];
 
 			Assert(expr != NULL);
 			atttype = exprType(expr);
 			attcollation = exprCollation(expr);
 
+			/*
+			 * The expression must be of a storable type (e.g., not RECORD).
+			 * The test is the same as for whether a table column is of a safe
+			 * type (which is why we needn't check for the non-expression
+			 * case).
+			 */
+			snprintf(partattname, sizeof(partattname), "%d", attn + 1);
+			CheckAttributeType(partattname,
+							   atttype, attcollation,
+							   NIL, CHKATYPE_IS_PARTKEY);
+
 			/*
 			 * Strip any top-level COLLATE clause.  This ensures that we treat
 			 * "x COLLATE y" and "(x COLLATE y)" alike.
diff --git a/src/include/catalog/heap.h b/src/include/catalog/heap.h
index eec71c29d5b..2e631378971 100644
--- a/src/include/catalog/heap.h
+++ b/src/include/catalog/heap.h
@@ -22,6 +22,7 @@
 /* flag bits for CheckAttributeType/CheckAttributeNamesTypes */
 #define CHKATYPE_ANYARRAY		0x01	/* allow ANYARRAY */
 #define CHKATYPE_ANYRECORD		0x02	/* allow RECORD and RECORD[] */
+#define CHKATYPE_IS_PARTKEY		0x04	/* attname is part key # not column */
 
 typedef struct RawColumnDefault
 {
diff --git a/src/test/regress/expected/create_table.out b/src/test/regress/expected/create_table.out
index f63016871ca..50de4b380a5 100644
--- a/src/test/regress/expected/create_table.out
+++ b/src/test/regress/expected/create_table.out
@@ -375,7 +375,7 @@ CREATE TABLE partitioned (
 ERROR:  cannot use subquery in partition key expression
 CREATE TABLE partitioned (
 	a int
-) PARTITION BY RANGE (('a'));
+) PARTITION BY RANGE ((42));
 ERROR:  cannot use constant expression as partition key
 CREATE FUNCTION const_func () RETURNS int AS $$ SELECT 1; $$ LANGUAGE SQL IMMUTABLE;
 CREATE TABLE partitioned (
@@ -402,6 +402,17 @@ CREATE TABLE partitioned (
 ERROR:  cannot use system column "xmin" in partition key
 LINE 3: ) PARTITION BY RANGE (xmin);
                               ^
+-- cannot use pseudotypes
+CREATE TABLE partitioned (
+	a int,
+	b int
+) PARTITION BY RANGE (((a, b)));
+ERROR:  partition key column 1 has pseudo-type record
+CREATE TABLE partitioned (
+	a int,
+	b int
+) PARTITION BY RANGE (a, ('unknown'));
+ERROR:  partition key column 2 has pseudo-type unknown
 -- functions in key must be immutable
 CREATE FUNCTION immut_func (a int) RETURNS int AS $$ SELECT a + random()::int; $$ LANGUAGE SQL;
 CREATE TABLE partitioned (
diff --git a/src/test/regress/sql/create_table.sql b/src/test/regress/sql/create_table.sql
index e835b65ac44..9a40d7b8cdf 100644
--- a/src/test/regress/sql/create_table.sql
+++ b/src/test/regress/sql/create_table.sql
@@ -361,7 +361,7 @@ CREATE TABLE partitioned (
 
 CREATE TABLE partitioned (
 	a int
-) PARTITION BY RANGE (('a'));
+) PARTITION BY RANGE ((42));
 
 CREATE FUNCTION const_func () RETURNS int AS $$ SELECT 1; $$ LANGUAGE SQL IMMUTABLE;
 CREATE TABLE partitioned (
@@ -384,6 +384,16 @@ CREATE TABLE partitioned (
 	a int
 ) PARTITION BY RANGE (xmin);
 
+-- cannot use pseudotypes
+CREATE TABLE partitioned (
+	a int,
+	b int
+) PARTITION BY RANGE (((a, b)));
+CREATE TABLE partitioned (
+	a int,
+	b int
+) PARTITION BY RANGE (a, ('unknown'));
+
 -- functions in key must be immutable
 CREATE FUNCTION immut_func (a int) RETURNS int AS $$ SELECT a + random()::int; $$ LANGUAGE SQL;
 CREATE TABLE partitioned (