diff --git a/sql/field.h b/sql/field.h
index 555ecf16ce4..499bf5e3c1f 100644
--- a/sql/field.h
+++ b/sql/field.h
@@ -828,10 +828,10 @@ public:
 
   utype	unireg_check;
   field_visibility_t invisible;
-  uint32	field_length;           // Length of field
-  uint32	flags;
-  uint16   field_index;           // field number in fields array
-  uchar	null_bit;                  // Bit used to test null bit
+  uint32        field_length;          // Length of field
+  uint32        flags;
+  field_index_t field_index;           // field number in fields array
+  uchar null_bit;                      // Bit used to test null bit
 
   /**
      If true, this field was created in create_tmp_field_from_item from a NULL
diff --git a/sql/item.h b/sql/item.h
index bb34ea316ea..273013c0a74 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -3277,7 +3277,7 @@ public:
   }
 };
 
-#define NO_CACHED_FIELD_INDEX ((uint16) ~0)
+#define NO_CACHED_FIELD_INDEX ((field_index_t) ~0U)
 
 class st_select_lex;
 
@@ -3354,7 +3354,7 @@ public:
     stmts for speeding up their re-execution. Holds NO_CACHED_FIELD_INDEX
     if index value is not known.
   */
-  uint16 cached_field_index;
+  field_index_t cached_field_index;
   /*
     Some Items resolved in another select should not be marked as dependency
     of the subquery where they are. During normal name resolution, we check
@@ -6752,7 +6752,7 @@ public:
   enum __attribute__((packed)) row_version_type {OLD_ROW, NEW_ROW};
   row_version_type row_version;
   /* Index of the field in the TABLE::field array */
-  uint16 field_idx;
+  field_index_t field_idx;
 
 private:
   /*
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 0ecba16730b..b5a671b3f37 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -11670,8 +11670,8 @@ static bool is_key_scan_ror(PARAM *param, uint keynr, uint8 nparts)
   
   for (KEY_PART_INFO *kp= table_key->key_part; kp < key_part; kp++)
   {
-    uint16 fieldnr= param->table->key_info[keynr].
-                    key_part[kp - table_key->key_part].fieldnr - 1;
+    field_index_t fieldnr= (param->table->key_info[keynr].
+                            key_part[kp - table_key->key_part].fieldnr - 1);
     if (param->table->field[fieldnr]->key_length() != kp->length)
       return FALSE;
   }
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 8c9f2de9192..82ee92c27ba 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -6982,7 +6982,7 @@ int mysql_table_grant(THD *thd, TABLE_LIST *table_list,
 
       while ((column = column_iter++))
       {
-        uint16 unused_field_idx= NO_CACHED_FIELD_INDEX;
+        field_index_t unused_field_idx= NO_CACHED_FIELD_INDEX;
         TABLE_LIST *dummy;
         Field *f=find_field_in_table_ref(thd, table_list, column->column.ptr(),
                                          column->column.length(),
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 0417244a01c..d9b305e7d74 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -6014,10 +6014,10 @@ find_field_in_natural_join(THD *thd, TABLE_LIST *table_ref, const char *name, si
 
 Field *
 find_field_in_table(THD *thd, TABLE *table, const char *name, size_t length,
-                    bool allow_rowid, uint16 *cached_field_index_ptr)
+                    bool allow_rowid, field_index_t *cached_field_index_ptr)
 {
   Field *field;
-  uint16 cached_field_index= *cached_field_index_ptr;
+  field_index_t cached_field_index= *cached_field_index_ptr;
   DBUG_ENTER("find_field_in_table");
   DBUG_PRINT("enter", ("table: '%s', field name: '%s'", table->alias.c_ptr(),
                        name));
@@ -6113,7 +6113,7 @@ find_field_in_table_ref(THD *thd, TABLE_LIST *table_list,
                         ignored_tables_list_t ignored_tables,
                         Item **ref,
                         bool check_privileges, bool allow_rowid,
-                        uint16 *cached_field_index_ptr,
+                        field_index_t *cached_field_index_ptr,
                         bool register_tree_change, TABLE_LIST **actual_table)
 {
   Field *fld;
diff --git a/sql/sql_base.h b/sql/sql_base.h
index 7a56d95bf2a..cafb5967480 100644
--- a/sql/sql_base.h
+++ b/sql/sql_base.h
@@ -205,11 +205,11 @@ find_field_in_table_ref(THD *thd, TABLE_LIST *table_list,
                         const char *table_name,
                         ignored_tables_list_t ignored_tables,
                         Item **ref, bool check_privileges, bool allow_rowid,
-                        uint16 *cached_field_index_ptr,
+                        field_index_t *cached_field_index_ptr,
                         bool register_tree_change, TABLE_LIST **actual_table);
 Field *
 find_field_in_table(THD *thd, TABLE *table, const char *name, size_t length,
-                    bool allow_rowid, uint16 *cached_field_index_ptr);
+                    bool allow_rowid, field_index_t *cached_field_index_ptr);
 Field *
 find_field_in_table_sef(TABLE *table, const char *name);
 Item ** find_item_in_list(Item *item, List<Item> &items, uint *counter,
diff --git a/sql/structs.h b/sql/structs.h
index d7568e02e29..fa0da6e0dbb 100644
--- a/sql/structs.h
+++ b/sql/structs.h
@@ -36,6 +36,9 @@ class Index_statistics;
 
 class THD;
 
+/* Array index type for table.field[] */
+typedef uint16 field_index_t;
+
 typedef struct st_date_time_format {
   uchar positions[8];
   char  time_separator;			/* Separator between hour and minute */
@@ -82,10 +85,10 @@ typedef struct st_key_part_info {	/* Info about a key part */
   */
   uint16 store_length;
   uint16 key_type;
-  uint16 fieldnr;                       /* Fieldnr begins counting from 1 */
+  field_index_t fieldnr;                /* Fieldnr begins counting from 1 */
   uint16 key_part_flag;                 /* 0 or HA_REVERSE_SORT */
   uint8 type;
-  uint8 null_bit;			/* Position to null_bit */
+  uint8 null_bit;                       /* Position to null_bit */
 } KEY_PART_INFO ;
 
 class engine_option_value;
diff --git a/sql/table.cc b/sql/table.cc
index f62b7496ce7..125e4f81a1b 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -115,7 +115,8 @@ static bool fix_type_pointers(const char ***typelib_value_names,
                               TYPELIB *point_to_type, uint types,
                               char *names, size_t names_length);
 
-static uint find_field(Field **fields, uchar *record, uint start, uint length);
+static field_index_t find_field(Field **fields, uchar *record, uint start,
+                                uint length);
 
 inline bool is_system_table_name(const char *name, size_t length);
 
@@ -3002,10 +3003,10 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write,
       {
         Field *field;
 	if (new_field_pack_flag <= 1)
-	  key_part->fieldnr= (uint16) find_field(share->field,
-                                                 share->default_values,
-                                                 (uint) key_part->offset,
-                                                 (uint) key_part->length);
+	  key_part->fieldnr= find_field(share->field,
+                                        share->default_values,
+                                        (uint) key_part->offset,
+                                        (uint) key_part->length);
 	if (!key_part->fieldnr)
           goto err;
 
@@ -4631,10 +4632,11 @@ fix_type_pointers(const char ***typelib_value_names,
    #  field number +1
 */
 
-static uint find_field(Field **fields, uchar *record, uint start, uint length)
+static field_index_t find_field(Field **fields, uchar *record, uint start,
+                                uint length)
 {
   Field **field;
-  uint i, pos;
+  field_index_t i, pos;
 
   pos= 0;
   for (field= fields, i=1 ; *field ; i++,field++)
diff --git a/sql/table.h b/sql/table.h
index 9c87f9809ff..1b8919f4e59 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -892,8 +892,8 @@ struct TABLE_SHARE
   */
   struct period_info_t
   {
-    uint16 start_fieldno;
-    uint16 end_fieldno;
+    field_index_t start_fieldno;
+    field_index_t end_fieldno;
     Lex_ident name;
     Lex_ident constr_name;
     uint unique_keys;
@@ -1909,14 +1909,14 @@ class IS_table_read_plan;
 constexpr uint frm_fieldno_size= 2;
 /** number of bytes used by key position number in frm */
 constexpr uint frm_keyno_size= 2;
-static inline uint16 read_frm_fieldno(const uchar *data)
+static inline field_index_t read_frm_fieldno(const uchar *data)
 { return uint2korr(data); }
-static inline void store_frm_fieldno(uchar *data, uint16 fieldno)
+static inline void store_frm_fieldno(uchar *data, field_index_t fieldno)
 { int2store(data, fieldno); }
 static inline uint16 read_frm_keyno(const uchar *data)
 { return uint2korr(data); }
-static inline void store_frm_keyno(uchar *data, uint16 fieldno)
-{ int2store(data, fieldno); }
+static inline void store_frm_keyno(uchar *data, uint16 keyno)
+{ int2store(data, keyno); }
 static inline size_t extra2_str_size(size_t len)
 { return (len > 255 ? 3 : 1) + len; }
 
diff --git a/sql/unireg.cc b/sql/unireg.cc
index 51dd1fb6e8c..2726b9a68c2 100644
--- a/sql/unireg.cc
+++ b/sql/unireg.cc
@@ -133,8 +133,9 @@ static uchar *extra2_write_index_properties(uchar *pos, const KEY *keyinfo,
   return pos;
 }
 
-static uint16
-get_fieldno_by_name(HA_CREATE_INFO *create_info, List<Create_field> &create_fields,
+static field_index_t
+get_fieldno_by_name(HA_CREATE_INFO *create_info,
+                    List<Create_field> &create_fields,
                     const Lex_ident &field_name)
 {
   List_iterator<Create_field> it(create_fields);
@@ -142,17 +143,17 @@ get_fieldno_by_name(HA_CREATE_INFO *create_info, List<Create_field> &create_fiel
 
   DBUG_ASSERT(field_name);
 
-  for (unsigned field_no = 0; (sql_field = it++); ++field_no)
+  for (field_index_t field_no= 0; (sql_field = it++); ++field_no)
   {
     if (field_name.streq(sql_field->field_name))
     {
-      DBUG_ASSERT(field_no <= uint16(~0U));
-      return uint16(field_no);
+      DBUG_ASSERT(field_no < NO_CACHED_FIELD_INDEX);
+      return field_no;
     }
   }
 
   DBUG_ASSERT(0); /* Not Reachable */
-  return 0;
+  return NO_CACHED_FIELD_INDEX;
 }
 
 static inline