Merge branch '5.5' into 10.0

sql/field.h

@@ -1,6 +1,6 @@
 #ifndef FIELD_INCLUDED
 #define FIELD_INCLUDED
-/* Copyright (c) 2000, 2013, Oracle and/or its affiliates.
+/* Copyright (c) 2000, 2015, Oracle and/or its affiliates.
    Copyright (c) 2008, 2015, MariaDB
 
    This program is free software; you can redistribute it and/or modify
@@ -977,6 +977,16 @@ public:
   /* Hash value */
   virtual void hash(ulong *nr, ulong *nr2);
 
+/**
+  Checks whether a string field is part of write_set.
+
+  @return
+    FALSE  - If field is not char/varchar/....
+           - If field is char/varchar/.. and is not part of write set.
+    TRUE   - If field is char/varchar/.. and is part of write set.
+*/
+  virtual bool is_updatable() const { return FALSE; }
+
   /* Check whether the field can be used as a join attribute in hash join */
   virtual bool hash_join_is_possible() { return TRUE; }
   virtual bool eq_cmp_as_binary() { return TRUE; }
@@ -1174,6 +1184,11 @@ public:
 
   int store_decimal(const my_decimal *d);
   uint32 max_data_length() const;
+  bool is_updatable() const
+  {
+    DBUG_ASSERT(table && table->write_set);
+    return bitmap_is_set(table->write_set, field_index);
+  }
   bool match_collation_to_optimize_range() const { return true; }
 };