bk commit into 5.1 tree (Justin.He:1.2486) BUG#27127

[justin.he]

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ChangeSet@stripped, 2007-03-22 12:16:52+08:00, Justin.He@stripped +1 -0
  Bug#27127, Incorrect behaviour of timestamp column with DEFAULT CURRENT_TIMESTAMP
  correct the bitmap_set_bit when a field is timestamp and described 
  with default CURRENT_TIMESTAMP or on update CURRENT_TIMESTAMP,
  then it will reduce a little time cost when the field doesnot need 
  to write.

  sql/sql_update.cc@stripped, 2007-03-22 12:16:49+08:00, Justin.He@stripped +4 -2
    here table->timestamp_field represent only the timestamp field related to
CURRENT_TIMESTAMP,
    when the timestamp_field_type is 0 or 1, it need not to write the field data further.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	Justin.He
# Host:	dev3-240.dev.cn.tlan
# Root:	/home/justin.he/mysql/mysql-5.1/bug27127-5.1-new-ndb-bj

--- 1.232/sql/sql_update.cc	2007-03-22 12:17:00 +08:00
+++ 1.233/sql/sql_update.cc	2007-03-22 12:17:00 +08:00
@@ -201,8 +201,10 @@
       table->timestamp_field_type= TIMESTAMP_NO_AUTO_SET;
     else
     {
-      bitmap_set_bit(table->write_set,
-                     table->timestamp_field->field_index);
+      if (table->timestamp_field_type == TIMESTAMP_AUTO_SET_ON_UPDATE ||
+          table->timestamp_field_type == TIMESTAMP_AUTO_SET_ON_BOTH)
+        bitmap_set_bit(table->write_set,
+                       table->timestamp_field->field_index);
     }
   }