System Versioning 1.0 pre5 [closes #407]

Merge branch '10.3' into trunk

Both field_visibility and VERS_HIDDEN_FLAG exist independently.

TODO:
VERS_HIDDEN_FLAG should be replaced with SYSTEM_INVISIBLE (or COMPLETELY_INVISIBLE?).

sql/table.h

@@ -335,6 +335,17 @@ enum enum_vcol_update_mode
   VCOL_UPDATE_FOR_REPLACE
 };
 
+/* Field visibility enums */
+
+enum field_visible_type{
+  NOT_INVISIBLE= 0,
+  USER_DEFINED_INVISIBLE,
+  /* automatically added by the server. Can be queried explicitly
+  in SELECT, otherwise invisible from anything" */
+  SYSTEM_INVISIBLE,
+  COMPLETELY_INVISIBLE,
+  MAX_BITS_INVISIBLE= 3
+};
 
 /**
   Category of table found in the table share.
@@ -673,6 +684,7 @@ struct TABLE_SHARE
   uint blob_fields;                     /* number of blob fields */
   uint varchar_fields;                  /* number of varchar fields */
   uint default_fields;                  /* number of default fields */
+  uint visible_fields;                  /* number of visible fields */
 
   uint default_expressions;
   uint table_check_constraints, field_check_constraints;
@@ -1559,8 +1571,8 @@ public:
   uint vers_user_fields() const
   {
     return s->versioned ?
-      s->fields - VERSIONING_FIELDS :
-      s->fields;
+      s->visible_fields - VERSIONING_FIELDS :
+      s->visible_fields;
   }
 };