Manual merge from mysql-trunk.

Conflicts:
  - mysql-test/suite/engines/funcs/t/disabled.def
  - mysql-test/suite/engines/iuds/t/disabled.def
  - mysql-test/suite/engines/iuds/t/insert_number.test

1 files changed, 19 insertions, 1 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 49a4c1c920d..fb2889aad87 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -1796,6 +1796,24 @@ bool agg_item_set_converter(DTCollation &coll, const char *fname,
                                   &dummy_offset))
       continue;
 
+    /*
+      No needs to add converter if an "arg" is NUMERIC or DATETIME
+      value (which is pure ASCII) and at the same time target DTCollation
+      is ASCII-compatible. For example, no needs to rewrite:
+        SELECT * FROM t1 WHERE datetime_field = '2010-01-01';
+      to
+        SELECT * FROM t1 WHERE CONVERT(datetime_field USING cs) = '2010-01-01';
+      
+      TODO: avoid conversion of any values with
+      repertoire ASCII and 7bit-ASCII-compatible,
+      not only numeric/datetime origin.
+    */
+    if ((*arg)->collation.derivation == DERIVATION_NUMERIC &&
+        (*arg)->collation.repertoire == MY_REPERTOIRE_ASCII &&
+        !((*arg)->collation.collation->state & MY_CS_NONASCII) &&
+        !(coll.collation->state & MY_CS_NONASCII))
+      continue;
+
     if (!(conv= (*arg)->safe_charset_converter(coll.collation)) &&
         ((*arg)->collation.repertoire == MY_REPERTOIRE_ASCII))
     {
@@ -5422,7 +5440,7 @@ int Item::save_in_field(Field *field, bool no_conversions)
   {
     double nr= val_real();
     if (null_value)
-      return set_field_to_null(field);
+      return set_field_to_null_with_conversions(field, no_conversions);
     field->set_notnull();
     error=field->store(nr);
   }