1 files changed, 25 insertions, 0 deletions
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index 8fd7273fd78..c9d6ca87fdb 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -941,6 +941,31 @@ TABLE *open_table(THD *thd,const char *db,const char *table_name,
     for (uint i=0 ; i < table->fields ; i++)
       table->field[i]->table_name=table->table_name;
   }
+#if MYSQL_VERSION_ID < 40100
+  /*
+    If per-connection "new" variable (represented by variables.new_mode)
+    is set then we should pretend that the length of TIMESTAMP field is 19.
+    The cheapest (from perfomance viewpoint) way to achieve that is to set
+    field_length of all Field_timestamp objects in a table after opening
+    it (to 19 if new_mode is true or to original field length otherwise).
+    We save value of new_mode variable in TABLE::timestamp_mode to
+    not perform this setup if new_mode value is the same between sequential
+    table opens.
+  */
+  my_bool new_mode= thd->variables.new_mode;
+  if (table->timestamp_mode != new_mode)
+  {
+    for (uint i=0 ; i < table->fields ; i++)
+    {
+      Field *field= table->field[i];
+
+      if (field->type() == FIELD_TYPE_TIMESTAMP)
+        field->field_length= new_mode ? 19 :
+                             ((Field_timestamp *)(field))->orig_field_length;
+    }
+    table->timestamp_mode= new_mode;
+  }
+#endif
   /* These variables are also set in reopen_table() */
   table->tablenr=thd->current_tablenr++;
   table->used_fields=0;