Fix for bug#18437 "Wrong values inserted with a before update trigger on

NDB table".

SQL-layer was not marking fields which were used in triggers as such. As
result these fields were not always properly retrieved/stored by handler
layer. So one might got wrong values or lost changes in triggers for NDB,
Federated and possibly InnoDB tables.
This fix solves the problem by marking fields used in triggers
appropriately.

Also this patch contains the following cleanup of ha_ndbcluster code:

We no longer rely on reading LEX::sql_command value in handler in order
to determine if we can enable optimization which allows us to handle REPLACE
statement in more efficient way by doing replaces directly in write_row()
method without reporting error to SQL-layer.
Instead we rely on SQL-layer informing us whether this optimization
applicable by calling handler::extra() method with
HA_EXTRA_WRITE_CAN_REPLACE flag.
As result we no longer apply this optimzation in cases when it should not
be used (e.g. if we have on delete triggers on table) and use in some
additional cases when it is applicable (e.g. for LOAD DATA REPLACE).

Finally this patch includes fix for bug#20728 "REPLACE does not work
correctly for NDB table with PK and unique index".
  
This was yet another problem which was caused by improper field mark-up.
During row replacement fields which weren't explicity used in REPLACE
statement were not marked as fields to be saved (updated) so they have
retained values from old row version. The fix is to mark all table
fields as set for REPLACE statement. Note that in 5.1 we already solve
this problem by notifying handler that it should save values from all
fields only in case when real replacement happens.

1 files changed, 8 insertions, 0 deletions

diff --git a/sql/sql_trigger.h b/sql/sql_trigger.h
index b67c22e0588..e736c3e0e1a 100644
--- a/sql/sql_trigger.h
+++ b/sql/sql_trigger.h
@@ -26,6 +26,11 @@ class Table_triggers_list: public Sql_alloc
   /* Triggers as SPs grouped by event, action_time */
   sp_head           *bodies[TRG_EVENT_MAX][TRG_ACTION_MAX];
   /*
+    Heads of the lists linking items for all fields used in triggers
+    grouped by event and action_time.
+  */
+  Item_trigger_field *trigger_fields[TRG_EVENT_MAX][TRG_ACTION_MAX];
+  /*
     Copy of TABLE::Field array with field pointers set to TABLE::record[1]
     buffer instead of TABLE::record[0] (used for OLD values in on UPDATE
     trigger and DELETE trigger when it is called for REPLACE).
@@ -82,6 +87,7 @@ public:
     record1_field(0), table(table_arg)
   {
     bzero((char *)bodies, sizeof(bodies));
+    bzero((char *)trigger_fields, sizeof(trigger_fields));
     bzero((char *)&subject_table_grants, sizeof(subject_table_grants));
   }
   ~Table_triggers_list();
@@ -119,6 +125,8 @@ public:
 
   void set_table(TABLE *new_table);
 
+  void mark_fields_used(THD *thd, trg_event_type event);
+
   friend class Item_trigger_field;
   friend int sp_cache_routines_and_add_tables_for_triggers(THD *thd, LEX *lex,
                                                             TABLE_LIST *table);