diff --git a/doc/src/sgml/bki.sgml b/doc/src/sgml/bki.sgml
index 4e7568f5ce..272a10a98c 100644
--- a/doc/src/sgml/bki.sgml
+++ b/doc/src/sgml/bki.sgml
@@ -119,7 +119,8 @@
    require all columns that should be non-nullable to be marked so
    in <structname>pg_attribute</structname>.  The bootstrap code will
    automatically mark catalog columns as <literal>NOT NULL</literal>
-   if they are fixed-width and are not preceded by any nullable column.
+   if they are fixed-width and are not preceded by any nullable or
+   variable-width column.
    Where this rule is inadequate, you can force correct marking by using
    <literal>BKI_FORCE_NOT_NULL</literal>
    and <literal>BKI_FORCE_NULL</literal> annotations as needed.
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 5480a024e0..45b7efbe46 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -770,25 +770,18 @@ DefineAttr(char *name, char *type, int attnum, int nullness)
 
 		/*
 		 * Mark as "not null" if type is fixed-width and prior columns are
-		 * too.  This corresponds to case where column can be accessed
-		 * directly via C struct declaration.
-		 *
-		 * oidvector and int2vector are also treated as not-nullable, even
-		 * though they are no longer fixed-width.
+		 * likewise fixed-width and not-null.  This corresponds to case where
+		 * column can be accessed directly via C struct declaration.
 		 */
-#define MARKNOTNULL(att) \
-		((att)->attlen > 0 || \
-		 (att)->atttypid == OIDVECTOROID || \
-		 (att)->atttypid == INT2VECTOROID)
-
-		if (MARKNOTNULL(attrtypes[attnum]))
+		if (attrtypes[attnum]->attlen > 0)
 		{
 			int			i;
 
 			/* check earlier attributes */
 			for (i = 0; i < attnum; i++)
 			{
-				if (!attrtypes[i]->attnotnull)
+				if (attrtypes[i]->attlen <= 0 ||
+					!attrtypes[i]->attnotnull)
 					break;
 			}
 			if (i == attnum)
diff --git a/src/backend/catalog/genbki.pl b/src/backend/catalog/genbki.pl
index b07537fbba..dc5f442397 100644
--- a/src/backend/catalog/genbki.pl
+++ b/src/backend/catalog/genbki.pl
@@ -713,8 +713,8 @@ sub gen_pg_attribute
 		push @tables_needing_macros, $table_name;
 
 		# Generate entries for user attributes.
-		my $attnum       = 0;
-		my $priornotnull = 1;
+		my $attnum          = 0;
+		my $priorfixedwidth = 1;
 		foreach my $attr (@{ $table->{columns} })
 		{
 			$attnum++;
@@ -722,8 +722,12 @@ sub gen_pg_attribute
 			$row{attnum}   = $attnum;
 			$row{attrelid} = $table->{relation_oid};
 
-			morph_row_for_pgattr(\%row, $schema, $attr, $priornotnull);
-			$priornotnull &= ($row{attnotnull} eq 't');
+			morph_row_for_pgattr(\%row, $schema, $attr, $priorfixedwidth);
+
+			# Update $priorfixedwidth --- must match morph_row_for_pgattr
+			$priorfixedwidth &=
+			  ($row{attnotnull} eq 't'
+				  && ($row{attlen} eq 'NAMEDATALEN' || $row{attlen} > 0));
 
 			# If it's bootstrapped, put an entry in postgres.bki.
 			print_bki_insert(\%row, $schema) if $table->{bootstrap};
@@ -765,13 +769,13 @@ sub gen_pg_attribute
 
 # Given $pgattr_schema (the pg_attribute schema for a catalog sufficient for
 # AddDefaultValues), $attr (the description of a catalog row), and
-# $priornotnull (whether all prior attributes in this catalog are not null),
+# $priorfixedwidth (all prior columns are fixed-width and not null),
 # modify the $row hashref for print_bki_insert.  This includes setting data
 # from the corresponding pg_type element and filling in any default values.
 # Any value not handled here must be supplied by caller.
 sub morph_row_for_pgattr
 {
-	my ($row, $pgattr_schema, $attr, $priornotnull) = @_;
+	my ($row, $pgattr_schema, $attr, $priorfixedwidth) = @_;
 	my $attname = $attr->{name};
 	my $atttype = $attr->{type};
 
@@ -801,19 +805,18 @@ sub morph_row_for_pgattr
 	{
 		$row->{attnotnull} = 'f';
 	}
-	elsif ($priornotnull)
+	elsif ($priorfixedwidth)
 	{
 
 		# attnotnull will automatically be set if the type is
-		# fixed-width and prior columns are all NOT NULL ---
-		# compare DefineAttr in bootstrap.c. oidvector and
-		# int2vector are also treated as not-nullable.
+		# fixed-width and prior columns are likewise fixed-width
+		# and NOT NULL --- compare DefineAttr in bootstrap.c.
+		# At this point the width of type name is still symbolic,
+		# so we need a special test.
 		$row->{attnotnull} =
-		    $type->{typname} eq 'oidvector'  ? 't'
-		  : $type->{typname} eq 'int2vector' ? 't'
-		  : $type->{typlen} eq 'NAMEDATALEN' ? 't'
-		  : $type->{typlen} > 0              ? 't'
-		  :                                    'f';
+		    $row->{attlen} eq 'NAMEDATALEN' ? 't'
+		  : $row->{attlen} > 0              ? 't'
+		  :                                   'f';
 	}
 	else
 	{
diff --git a/src/include/catalog/genbki.h b/src/include/catalog/genbki.h
index 4a6c8636da..8cac7ec878 100644
--- a/src/include/catalog/genbki.h
+++ b/src/include/catalog/genbki.h
@@ -46,8 +46,8 @@
 /*
  * Variable-length catalog fields (except possibly the first not nullable one)
  * should not be visible in C structures, so they are made invisible by #ifdefs
- * of an undefined symbol.  See also MARKNOTNULL in bootstrap.c for how this is
- * handled.
+ * of an undefined symbol.  See also the BOOTCOL_NULL_AUTO code in bootstrap.c
+ * for how this is handled.
  */
 #undef CATALOG_VARLEN
 
diff --git a/src/include/catalog/pg_index.h b/src/include/catalog/pg_index.h
index d3d7ea77fb..4a642f336f 100644
--- a/src/include/catalog/pg_index.h
+++ b/src/include/catalog/pg_index.h
@@ -44,12 +44,14 @@ CATALOG(pg_index,2610,IndexRelationId) BKI_SCHEMA_MACRO
 	bool		indisreplident; /* is this index the identity for replication? */
 
 	/* variable-length fields start here, but we allow direct access to indkey */
-	int2vector	indkey;			/* column numbers of indexed cols, or 0 */
+	int2vector	indkey BKI_FORCE_NOT_NULL;	/* column numbers of indexed cols,
+											 * or 0 */
 
 #ifdef CATALOG_VARLEN
-	oidvector	indcollation;	/* collation identifiers */
-	oidvector	indclass;		/* opclass identifiers */
-	int2vector	indoption;		/* per-column flags (AM-specific meanings) */
+	oidvector	indcollation BKI_FORCE_NOT_NULL;	/* collation identifiers */
+	oidvector	indclass BKI_FORCE_NOT_NULL;	/* opclass identifiers */
+	int2vector	indoption BKI_FORCE_NOT_NULL;	/* per-column flags
+												 * (AM-specific meanings) */
 	pg_node_tree indexprs;		/* expression trees for index attributes that
 								 * are not simple column references; one for
 								 * each zero entry in indkey[] */
diff --git a/src/include/catalog/pg_partitioned_table.h b/src/include/catalog/pg_partitioned_table.h
index a73cd0d3a4..7ee0419373 100644
--- a/src/include/catalog/pg_partitioned_table.h
+++ b/src/include/catalog/pg_partitioned_table.h
@@ -41,13 +41,17 @@ CATALOG(pg_partitioned_table,3350,PartitionedRelationId)
 	 * field of a heap tuple can be reliably accessed using its C struct
 	 * offset, as previous fields are all non-nullable fixed-length fields.
 	 */
-	int2vector	partattrs;		/* each member of the array is the attribute
-								 * number of a partition key column, or 0 if
-								 * the column is actually an expression */
+	int2vector	partattrs BKI_FORCE_NOT_NULL;	/* each member of the array is
+												 * the attribute number of a
+												 * partition key column, or 0
+												 * if the column is actually
+												 * an expression */
 
 #ifdef CATALOG_VARLEN
-	oidvector	partclass;		/* operator class to compare keys */
-	oidvector	partcollation;	/* user-specified collation for keys */
+	oidvector	partclass BKI_FORCE_NOT_NULL;	/* operator class to compare
+												 * keys */
+	oidvector	partcollation BKI_FORCE_NOT_NULL;	/* user-specified
+													 * collation for keys */
 	pg_node_tree partexprs;		/* list of expressions in the partition key;
 								 * one item for each zero entry in partattrs[] */
 #endif
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 65e8c9f054..b50fa25dbd 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -92,7 +92,7 @@ CATALOG(pg_proc,1255,ProcedureRelationId) BKI_BOOTSTRAP BKI_ROWTYPE_OID(81,Proce
 	 */
 
 	/* parameter types (excludes OUT params) */
-	oidvector	proargtypes BKI_LOOKUP(pg_type);
+	oidvector	proargtypes BKI_LOOKUP(pg_type) BKI_FORCE_NOT_NULL;
 
 #ifdef CATALOG_VARLEN
 
diff --git a/src/include/catalog/pg_statistic_ext.h b/src/include/catalog/pg_statistic_ext.h
index a8cb16997a..8747903fc7 100644
--- a/src/include/catalog/pg_statistic_ext.h
+++ b/src/include/catalog/pg_statistic_ext.h
@@ -47,7 +47,7 @@ CATALOG(pg_statistic_ext,3381,StatisticExtRelationId)
 	 * variable-length fields start here, but we allow direct access to
 	 * stxkeys
 	 */
-	int2vector	stxkeys;		/* array of column keys */
+	int2vector	stxkeys BKI_FORCE_NOT_NULL; /* array of column keys */
 
 #ifdef CATALOG_VARLEN
 	char		stxkind[1] BKI_FORCE_NOT_NULL;	/* statistics kinds requested
diff --git a/src/include/catalog/pg_trigger.h b/src/include/catalog/pg_trigger.h
index 9612b9bdd6..fa5761b784 100644
--- a/src/include/catalog/pg_trigger.h
+++ b/src/include/catalog/pg_trigger.h
@@ -54,7 +54,8 @@ CATALOG(pg_trigger,2620,TriggerRelationId)
 	 * Variable-length fields start here, but we allow direct access to
 	 * tgattr. Note: tgattr and tgargs must not be null.
 	 */
-	int2vector	tgattr;			/* column numbers, if trigger is on columns */
+	int2vector	tgattr BKI_FORCE_NOT_NULL;	/* column numbers, if trigger is
+											 * on columns */
 
 #ifdef CATALOG_VARLEN
 	bytea		tgargs BKI_FORCE_NOT_NULL;	/* first\000second\000tgnargs\000 */