A fix and a test case for Bug#26141 mixing table types in trigger

causes full table lock on innodb table.
Also fixes Bug#28502 Triggers that update another innodb table 
will block on X lock unnecessarily (duplciate).
Code review fixes.

Both bugs' synopses are misleading: InnoDB table is
not X locked. The statements, however, cannot proceed concurrently, 
but this happens due to lock conflicts for tables used in triggers,
not for the InnoDB table. 

If a user had an InnoDB table, and two triggers, AFTER UPDATE and 
AFTER INSERT, competing for different resources (e.g. two distinct
MyISAM tables), then these two triggers would not be able to execute
concurrently. Moreover, INSERTS/UPDATES of the InnoDB table would
not be able to run concurrently. 
The problem had other side-effects (see respective bug reports).

This behavior was a consequence of a shortcoming of the pre-locking
algorithm, which would not distinguish between different DML operations
(e.g. INSERT and DELETE) and pre-lock all the tables
that are used by any trigger defined on the subject table.

The idea of the fix is to extend the pre-locking algorithm to keep track,
for each table, what DML operation it is used for and not
load triggers that are known to never be fired.


mysql-test/r/trigger-trans.result:
  Update results (Bug#26141)
mysql-test/r/trigger.result:
  Update results (Bug#28502)
mysql-test/t/trigger-trans.test:
  Add a test case for Bug#26141 mixing table types in trigger causes 
  full table lock on innodb table.
mysql-test/t/trigger.test:
  Add a test case for Bug#28502 Triggers that update another innodb 
  table will block echo on X lock unnecessarily. Add more test 
  coverage for triggers.
sql/item.h:
  enum trg_event_type is needed in table.h
sql/sp.cc:
  Take into account table_list->trg_event_map when determining
  what tables to pre-lock. 
  
  After this change, if we attempt to fire a 
  trigger for which we had not pre-locked any tables, error
  'Table was not locked with LOCK TABLES' will be printed.
  This, however, should never happen, provided the pre-locking
  algorithm has no programming bugs.
  
  Previously a trigger key in the sroutines hash was based on the name 
  of the table the trigger belongs to. This was possible because we would
  always add to the pre-locking list all the triggers defined for a table when
  handling this table.
  Now the key is based on the name of the trigger, owing
  to the fact that a trigger name must be unique in the database it
  belongs to.
sql/sp_head.cc:
  Generate sroutines hash key in init_spname(). This is a convenient
  place since there we have all the necessary information and can
  avoid an extra alloc.
  
  Maintain and merge trg_event_map when adding and merging elements
  of the pre-locking list.
sql/sp_head.h:
  Add ,m_sroutines_key member, used when inserting the sphead for a
  trigger into the cache of routines used by a statement.
  Previously the key was based on the table name the trigger belonged
  to, since for a given table we would add to the sroutines list
  all the triggers defined on it.
sql/sql_lex.cc:
  Introduce a new lex step: set_trg_event_type_for_tables().
  It is called when we have finished parsing but before opening
  and locking tables. Now this step is used to evaluate for each
  TABLE_LIST instance which INSERT/UPDATE/DELETE operation, if any,
  it is used in.
  In future this method could be extended to aggregate other information
  that is hard to aggregate during parsing.
sql/sql_lex.h:
  Add declaration for set_trg_event_type_for_tables().
sql/sql_parse.cc:
  Call set_trg_event_type_for_tables() after MYSQLparse(). Remove tabs.
sql/sql_prepare.cc:
  Call set_trg_event_type_for_tables() after  MYSQLparse().
sql/sql_trigger.cc:
  Call set_trg_event_type_for_tables() after MYSQLparse().
sql/sql_trigger.h:
  Remove an obsolete member.
sql/sql_view.cc:
  Call set_trg_event_type_for_tables() after MYSQLparse().
sql/sql_yacc.yy:
  Move assignment of sp_head::m_type before calling sp_head::init_spname(), 
  one is now used inside another.
sql/table.cc:
  Implement TABLE_LIST::set_trg_event_map() - a method that calculates
  wh triggers may be fired on this table when executing a statement.
sql/table.h:
  Add missing declarations.
  Move declaration of trg_event_type from item.h (it will be needed for 
  trg_event_map bitmap when we start using Bitmap template instead
  of uint8).

14 files changed, 293 insertions, 57 deletions

diff --git a/sql/item.h b/sql/item.h
index 58e3ec439b4..07bf7fec0ea 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -2309,14 +2309,6 @@ enum trg_action_time_type
   TRG_ACTION_BEFORE= 0, TRG_ACTION_AFTER= 1, TRG_ACTION_MAX
 };
 
-/*
-  Event on which trigger is invoked.
-*/
-enum trg_event_type
-{
-  TRG_EVENT_INSERT= 0 , TRG_EVENT_UPDATE= 1, TRG_EVENT_DELETE= 2, TRG_EVENT_MAX
-};
-
 class Table_triggers_list;
 
 /*
diff --git a/sql/sp.cc b/sql/sp.cc
index 3c8ebed4ae6..c0e7d5e2271 100644
--- a/sql/sp.cc
+++ b/sql/sp.cc
@@ -440,6 +440,19 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp,
     lex_start(thd);
     thd->spcont= NULL;
     ret= MYSQLparse(thd);
+
+    if (ret == 0)
+    {
+      /*
+        Not strictly necessary to invoke this method here, since we know
+        that we've parsed CREATE PROCEDURE/FUNCTION and not an
+        UPDATE/DELETE/INSERT/REPLACE/LOAD/CREATE TABLE, but we try to
+        maintain the invariant that this method is called for each
+        distinct statement, in case its logic is extended with other
+        types of analyses in future.
+      */
+      newlex.set_trg_event_type_for_tables();
+    }
   }
 
   if (ret || thd->is_fatal_error || newlex.sphead == NULL)
@@ -1742,31 +1755,39 @@ sp_cache_routines_and_add_tables_for_triggers(THD *thd, LEX *lex,
                                               TABLE_LIST *table)
 {
   int ret= 0;
-  Table_triggers_list *triggers= table->table->triggers;
-  if (add_used_routine(lex, thd->stmt_arena, &triggers->sroutines_key,
-                       table->belong_to_view))
+
+  Sroutine_hash_entry **last_cached_routine_ptr=
+    (Sroutine_hash_entry **)lex->sroutines_list.next;
+
+  if (static_cast<int>(table->lock_type) >=
+      static_cast<int>(TL_WRITE_ALLOW_WRITE))
   {
-    Sroutine_hash_entry **last_cached_routine_ptr=
-                            (Sroutine_hash_entry **)lex->sroutines_list.next;
     for (int i= 0; i < (int)TRG_EVENT_MAX; i++)
     {
-      for (int j= 0; j < (int)TRG_ACTION_MAX; j++)
+      if (table->trg_event_map &
+          static_cast<uint8>(1 << static_cast<int>(i)))
       {
-        if (triggers->bodies[i][j])
+        for (int j= 0; j < (int)TRG_ACTION_MAX; j++)
         {
-          (void)triggers->bodies[i][j]->
-                add_used_tables_to_table_list(thd, &lex->query_tables_last,
-                                              table->belong_to_view);
-          sp_update_stmt_used_routines(thd, lex,
-                                       &triggers->bodies[i][j]->m_sroutines,
-                                       table->belong_to_view);
+          /* We can have only one trigger per action type currently */
+          sp_head *trigger= table->table->triggers->bodies[i][j];
+          if (trigger &&
+              add_used_routine(lex, thd->stmt_arena, &trigger->m_sroutines_key,
+                               table->belong_to_view))
+          {
+            trigger->add_used_tables_to_table_list(thd, &lex->query_tables_last,
+                                                   table->belong_to_view);
+            sp_update_stmt_used_routines(thd, lex,
+                                         &trigger->m_sroutines,
+                                         table->belong_to_view);
+          }
         }
       }
     }
-    ret= sp_cache_routines_and_add_tables_aux(thd, lex,
-                                              *last_cached_routine_ptr, 
-                                              FALSE, NULL);
   }
+  ret= sp_cache_routines_and_add_tables_aux(thd, lex,
+                                            *last_cached_routine_ptr,
+                                            FALSE, NULL);
   return ret;
 }
 
diff --git a/sql/sp_head.cc b/sql/sp_head.cc
index d939fd20b9b..0ac1db336d0 100644
--- a/sql/sp_head.cc
+++ b/sql/sp_head.cc
@@ -478,12 +478,35 @@ sp_head::init(LEX *lex)
   */
   lex->trg_table_fields.empty();
   my_init_dynamic_array(&m_instr, sizeof(sp_instr *), 16, 8);
-  m_param_begin= m_param_end= m_body_begin= 0;
-  m_qname.str= m_db.str= m_name.str= m_params.str=
-    m_body.str= m_defstr.str= 0;
-  m_qname.length= m_db.length= m_name.length= m_params.length=
-    m_body.length= m_defstr.length= 0;
+
+  m_param_begin= NULL;
+  m_param_end= NULL;
+
+  m_body_begin= NULL ;
+
+  m_qname.str= NULL;
+  m_qname.length= 0;
+
+  m_db.str= NULL;
+  m_db.length= 0;
+
+  m_name.str= NULL;
+  m_name.length= 0;
+
+  m_params.str= NULL;
+  m_params.length= 0;
+
+  m_body.str= NULL;
+  m_body.length= 0;
+
+  m_defstr.str= NULL;
+  m_defstr.length= 0;
+
+  m_sroutines_key.str= NULL;
+  m_sroutines_key.length= 0;
+
   m_return_field_def.charset= NULL;
+
   DBUG_VOID_RETURN;
 }
 
@@ -509,9 +532,14 @@ sp_head::init_sp_name(THD *thd, sp_name *spname)
   if (spname->m_qname.length == 0)
     spname->init_qname(thd);
 
-  m_qname.length= spname->m_qname.length;
-  m_qname.str= strmake_root(thd->mem_root, spname->m_qname.str,
-                            m_qname.length);
+  m_sroutines_key.length= spname->m_sroutines_key.length;
+  m_sroutines_key.str= memdup_root(thd->mem_root,
+                                   spname->m_sroutines_key.str,
+                                   spname->m_sroutines_key.length + 1);
+  m_sroutines_key.str[0]= static_cast<char>(m_type);
+
+  m_qname.length= m_sroutines_key.length - 1;
+  m_qname.str= m_sroutines_key.str + 1;
 
   DBUG_VOID_RETURN;
 }
@@ -1796,8 +1824,11 @@ sp_head::restore_lex(THD *thd)
 {
   DBUG_ENTER("sp_head::restore_lex");
   LEX *sublex= thd->lex;
-  LEX *oldlex= (LEX *)m_lex.pop();
+  LEX *oldlex;
+
+  sublex->set_trg_event_type_for_tables();
 
+  oldlex= (LEX *)m_lex.pop();
   if (! oldlex)
     return;			// Nothing to restore
 
@@ -3429,6 +3460,7 @@ typedef struct st_sp_table
   thr_lock_type lock_type; /* lock type used for prelocking */
   uint lock_count;
   uint query_lock_count;
+  uint8 trg_event_map;
 } SP_TABLE;
 
 byte *
@@ -3515,6 +3547,7 @@ sp_head::merge_table_list(THD *thd, TABLE_LIST *table, LEX *lex_for_tmp_check)
         tab->query_lock_count++;
         if (tab->query_lock_count > tab->lock_count)
           tab->lock_count++;
+        tab->trg_event_map|= table->trg_event_map;
       }
       else
       {
@@ -3536,6 +3569,7 @@ sp_head::merge_table_list(THD *thd, TABLE_LIST *table, LEX *lex_for_tmp_check)
         tab->db_length= table->db_length;
         tab->lock_type= table->lock_type;
         tab->lock_count= tab->query_lock_count= 1;
+        tab->trg_event_map= table->trg_event_map;
 	my_hash_insert(&m_sptabs, (byte *)tab);
       }
     }
@@ -3613,6 +3647,7 @@ sp_head::add_used_tables_to_table_list(THD *thd,
       table->cacheable_table= 1;
       table->prelocking_placeholder= 1;
       table->belong_to_view= belong_to_view;
+      table->trg_event_map= stab->trg_event_map;
 
       /* Everyting else should be zeroed */
 
diff --git a/sql/sp_head.h b/sql/sp_head.h
index ed99885ae9a..ebe40ce9c87 100644
--- a/sql/sp_head.h
+++ b/sql/sp_head.h
@@ -130,6 +130,12 @@ public:
   st_sp_chistics *m_chistics;
   ulong m_sql_mode;		// For SHOW CREATE and execution
   LEX_STRING m_qname;		// db.name
+  /**
+    Key representing routine in the set of stored routines used by statement.
+    [routine_type]db.name\0
+    @sa sp_name::m_sroutines_key
+  */
+  LEX_STRING m_sroutines_key;
   LEX_STRING m_db;
   LEX_STRING m_name;
   LEX_STRING m_params;
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index dbce1e38139..c37d77345b6 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -2034,6 +2034,27 @@ void st_select_lex_unit::set_limit(SELECT_LEX *sl)
 }
 
 
+/**
+  Update the parsed tree with information about triggers that
+  may be fired when executing this statement.
+*/
+
+void st_lex::set_trg_event_type_for_tables()
+{
+  /*
+    Do not iterate over sub-selects, only the tables in the outermost
+    SELECT_LEX can be modified, if any.
+  */
+  TABLE_LIST *tables= select_lex.get_table_list();
+
+  while (tables)
+  {
+    tables->set_trg_event_type(this);
+    tables= tables->next_local;
+  }
+}
+
+
 /*
   Unlink the first table from the global table list and the first table from
   outer select (lex->select_lex) local list
diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index 25a6c31e21c..bfa6c05974f 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -1188,6 +1188,8 @@ typedef struct st_lex : public Query_tables_list
       un->uncacheable|= cause;
     }
   }
+  void set_trg_event_type_for_tables();
+
   TABLE_LIST *unlink_first_table(bool *link_to_local);
   void link_first_table_back(TABLE_LIST *first, bool link_to_local);
   void first_lists_tables_same();
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 124fcff9517..91c51641fc0 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -6080,8 +6080,9 @@ void mysql_parse(THD *thd, const char *inBuf, uint length,
               (thd->query_length= (ulong)(lip.found_semicolon - thd->query)))
             thd->query_length--;
           /* Actually execute the query */
-	  mysql_execute_command(thd);
-	  query_cache_end_of_result(thd);
+          lex->set_trg_event_type_for_tables();
+          mysql_execute_command(thd);
+          query_cache_end_of_result(thd);
 	}
       }
     }
diff --git a/sql/sql_prepare.cc b/sql/sql_prepare.cc
index 567f92b55ba..c993ce32e50 100644
--- a/sql/sql_prepare.cc
+++ b/sql/sql_prepare.cc
@@ -2826,6 +2826,7 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len)
   lex_start(thd);
   lex->safe_to_cache_query= FALSE;
   int err= MYSQLparse((void *)thd);
+  lex->set_trg_event_type_for_tables();
 
   error= err || thd->is_fatal_error ||
       thd->net.report_error || init_param_array(this);
diff --git a/sql/sql_trigger.cc b/sql/sql_trigger.cc
index 5762614e47f..6e4b5defb97 100644
--- a/sql/sql_trigger.cc
+++ b/sql/sql_trigger.cc
@@ -943,17 +943,6 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
       table->triggers= triggers;
 
       /*
-        Construct key that will represent triggers for this table in the set
-        of routines used by statement.
-      */
-      triggers->sroutines_key.length= 1+strlen(db)+1+strlen(table_name)+1;
-      if (!(triggers->sroutines_key.str=
-              alloc_root(&table->mem_root, triggers->sroutines_key.length)))
-        DBUG_RETURN(1);
-      triggers->sroutines_key.str[0]= TYPE_ENUM_TRIGGER;
-      strxmov(triggers->sroutines_key.str+1, db, ".", table_name, NullS);
-
-      /*
         TODO: This could be avoided if there is no triggers
               for UPDATE and DELETE.
       */
@@ -991,6 +980,15 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
           DBUG_ASSERT(lex.sphead == 0);
           goto err_with_lex_cleanup;
         }
+        /*
+          Not strictly necessary to invoke this method here, since we know
+          that we've parsed CREATE TRIGGER and not an
+          UPDATE/DELETE/INSERT/REPLACE/LOAD/CREATE TABLE, but we try to
+          maintain the invariant that this method is called for each
+          distinct statement, in case its logic is extended with other
+          types of analyses in future.
+        */
+        lex.set_trg_event_type_for_tables();
 
         lex.sphead->set_info(0, 0, &lex.sp_chistics, (ulong) *trg_sql_mode);
 
@@ -1550,6 +1548,12 @@ bool Table_triggers_list::process_triggers(THD *thd, trg_event_type event,
       new_field= record1_field;
       old_field= trigger_table->field;
     }
+    /*
+      This trigger must have been processed by the pre-locking
+      algorithm.
+    */
+    DBUG_ASSERT(trigger_table->pos_in_table_list->trg_event_map &
+                static_cast<uint>(1 << static_cast<int>(event)));
 
     thd->reset_sub_statement_state(&statement_state, SUB_STMT_TRIGGER);
     err_status= sp_trigger->execute_trigger
@@ -1568,7 +1572,7 @@ bool Table_triggers_list::process_triggers(THD *thd, trg_event_type event,
   SYNOPSIS
     mark_fields_used()
       thd    Current thread context
-      event  Type of event triggers for which we are going to inspect
+      event  Type of event triggers for which we are going to ins
 
   DESCRIPTION
     This method marks fields of subject table which are read/set in its
diff --git a/sql/sql_trigger.h b/sql/sql_trigger.h
index b029a70ca20..1dc573995f1 100644
--- a/sql/sql_trigger.h
+++ b/sql/sql_trigger.h
@@ -56,14 +56,6 @@ class Table_triggers_list: public Sql_alloc
     updating trigger definitions during RENAME TABLE.
   */
   List<LEX_STRING>  on_table_names_list;
-  /*
-    Key representing triggers for this table in set of all stored
-    routines used by statement.
-    TODO: We won't need this member once triggers namespace will be
-    database-wide instead of table-wide because then we will be able
-    to use key based on sp_name as for other stored routines.
-  */
-  LEX_STRING        sroutines_key;
 
   /*
     Grant information for each trigger (pair: subject table, trigger definer).
diff --git a/sql/sql_view.cc b/sql/sql_view.cc
index 6c94d388d0e..7857ba267c5 100644
--- a/sql/sql_view.cc
+++ b/sql/sql_view.cc
@@ -1153,7 +1153,20 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
       */
       for (tbl= view_main_select_tables; tbl; tbl= tbl->next_local)
         tbl->lock_type= table->lock_type;
+      /*
+        If the view is mergeable, we might want to
+        INSERT/UPDATE/DELETE into tables of this view. Preserve the
+        original sql command and 'duplicates' of the outer lex.
+        This is used later in set_trg_event_type_for_command.
+      */
+      lex->sql_command= old_lex->sql_command;
+      lex->duplicates= old_lex->duplicates;
     }
+    /*
+      This method has a dependency on the proper lock type being set,
+      so in case of views should be called here.
+    */
+    lex->set_trg_event_type_for_tables();
 
     /*
       If we are opening this view as part of implicit LOCK TABLES, then
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 949f3ed4161..8cc6642ae7e 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -9644,13 +9644,13 @@ trigger_tail:
 	    MYSQL_YYABORT;
 	  sp->reset_thd_mem_root(thd);
 	  sp->init(lex);
+	  sp->m_type= TYPE_ENUM_TRIGGER;
           sp->init_sp_name(thd, $3);
 	
 	  lex->stmt_definition_begin= $2;
           lex->ident.str= $7;
           lex->ident.length= $10 - $7;
 
-	  sp->m_type= TYPE_ENUM_TRIGGER;
 	  lex->sphead= sp;
 	  lex->spname= $3;
 	  /*
@@ -9728,9 +9728,9 @@ sp_tail:
 	  sp= new sp_head();
 	  sp->reset_thd_mem_root(YYTHD);
 	  sp->init(lex);
+	  sp->m_type= TYPE_ENUM_PROCEDURE;
           sp->init_sp_name(YYTHD, $3);
 
-	  sp->m_type= TYPE_ENUM_PROCEDURE;
 	  lex->sphead= sp;
 	  /*
 	   * We have to turn of CLIENT_MULTI_QUERIES while parsing a
diff --git a/sql/table.cc b/sql/table.cc
index 899d0ab2ed0..9c3e7618aa0 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -1776,6 +1776,135 @@ void st_table::reset_item_list(List<Item> *item_list) const
   }
 }
 
+
+/**
+  Set the initial purpose of this TABLE_LIST object in the list of
+  used tables. We need to track this information on table-by-
+  table basis, since when this table becomes an element of the
+  pre-locked list, it's impossible to identify which SQL
+  sub-statement it has been originally used in.
+
+  E.g.:
+
+  User request:                 SELECT * FROM t1 WHERE f1();
+  FUNCTION f1():                DELETE FROM t2; RETURN 1;
+  BEFORE DELETE trigger on t2:  INSERT INTO t3 VALUES (old.a);
+
+  For this user request, the pre-locked list will contain t1, t2, t3
+  table elements, each needed for different DML.
+
+  This method is called immediately after parsing for tables
+  of the table list of the top-level select lex.
+
+  The trigger event map is updated to reflect INSERT, UPDATE, DELETE,
+  REPLACE, LOAD DATA, CREATE TABLE .. SELECT, CREATE TABLE ..
+  REPLACE SELECT statements, and additionally ON DUPLICATE KEY UPDATE
+  clause.
+*/
+
+void
+TABLE_LIST::set_trg_event_type(const st_lex *lex)
+{
+  enum trg_event_type trg_event;
+
+  /*
+    Some auxiliary operations
+    (e.g. GRANT processing) create TABLE_LIST instances outside
+    the parser. Additionally, some commands (e.g. OPTIMIZE) change
+    the lock type for a table only after parsing is done. Luckily,
+    these do not fire triggers and do not need to pre-load them.
+    For these TABLE_LISTs set_trg_event_type is never called, and
+    trg_event_map is always empty. That means that the pre-locking
+    algorithm will ignore triggers defined on these tables, if
+    any, and the execution will either fail with an assert in
+    sql_trigger.cc or with an error that a used table was not
+    pre-locked, in case of a production build.
+
+    TODO: this usage pattern creates unnecessary module dependencies
+    and should be rewritten to go through the parser.
+    Table list instances created outside the parser in most cases
+    refer to mysql.* system tables. It is not allowed to have
+    a trigger on a system table, but keeping track of
+    initialization provides extra safety in case this limitation
+    is circumvented.
+  */
+
+  /*
+    This is a fast check to filter out statements that do
+    not change data, or tables  on the right side, in case of
+    INSERT .. SELECT, CREATE TABLE .. SELECT and so on.
+    Here we also filter out OPTIMIZE statement and non-updateable
+    views, for which lock_type is TL_UNLOCK or TL_READ after
+    parsing.
+  */
+  if (static_cast<int>(lock_type) < static_cast<int>(TL_WRITE_ALLOW_WRITE))
+    return;
+
+  switch (lex->sql_command) {
+  /*
+    Basic INSERT. If there is an additional ON DUPLIATE KEY UPDATE
+    clause, it will be handled later in this method.
+  */
+  case SQLCOM_INSERT:                           /* fall through */
+  case SQLCOM_INSERT_SELECT:
+  /*
+    LOAD DATA ... INFILE is expected to fire BEFORE/AFTER INSERT
+    triggers.
+    If the statement also has REPLACE clause, it will be
+    handled later in this method.
+  */
+  case SQLCOM_LOAD:                             /* fall through */
+  /*
+    REPLACE is semantically equivalent to INSERT. In case
+    of a primary or unique key conflict, it deletes the old
+    record and inserts a new one. So we also may need to
+    fire ON DELETE triggers. This functionality is handled
+    later in this method.
+  */
+  case SQLCOM_REPLACE:                          /* fall through */
+  case SQLCOM_REPLACE_SELECT:
+  /*
+    CREATE TABLE ... SELECT defaults to INSERT if the table or
+    view already exists. REPLACE option of CREATE TABLE ...
+    REPLACE SELECT is handled later in this method.
+  */
+  case SQLCOM_CREATE_TABLE:
+    trg_event= TRG_EVENT_INSERT;
+    break;
+  /* Basic update and multi-update */
+  case SQLCOM_UPDATE:                           /* fall through */
+  case SQLCOM_UPDATE_MULTI:
+    trg_event= TRG_EVENT_UPDATE;
+    break;
+  /* Basic delete and multi-delete */
+  case SQLCOM_DELETE:                           /* fall through */
+  case SQLCOM_DELETE_MULTI:
+    trg_event= TRG_EVENT_DELETE;
+    break;
+  default:
+    /*
+      OK to return, since value of 'duplicates' is irrelevant
+      for non-updating commands.
+    */
+    return;
+  }
+  trg_event_map|= static_cast<uint8>(1 << static_cast<int>(trg_event));
+
+  switch (lex->duplicates) {
+  case DUP_UPDATE:
+    trg_event= TRG_EVENT_UPDATE;
+    break;
+  case DUP_REPLACE:
+    trg_event= TRG_EVENT_DELETE;
+    break;
+  case DUP_ERROR:
+  default:
+    return;
+  }
+  trg_event_map|= static_cast<uint8>(1 << static_cast<int>(trg_event));
+}
+
+
 /*
   calculate md5 of query
 
diff --git a/sql/table.h b/sql/table.h
index b29ef8c6566..f8f7d7f06b7 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -59,6 +59,17 @@ enum tmp_table_type {NO_TMP_TABLE=0,
                      NON_TRANSACTIONAL_TMP_TABLE=1, TRANSACTIONAL_TMP_TABLE=2,
                      SYSTEM_TMP_TABLE=3};
 
+
+/** Event on which trigger is invoked. */
+enum trg_event_type
+{
+  TRG_EVENT_INSERT= 0,
+  TRG_EVENT_UPDATE= 1,
+  TRG_EVENT_DELETE= 2,
+  TRG_EVENT_MAX
+};
+
+
 enum frm_type_enum
 {
   FRMTYPE_ERROR= 0,
@@ -702,6 +713,13 @@ struct TABLE_LIST
   */
   bool          create;
 
+  /**
+    Indicates what triggers we need to pre-load for this TABLE_LIST
+    when opening an associated TABLE. This is filled after
+    the parsed tree is created.
+  */
+  uint8 trg_event_map;
+
   enum enum_schema_table_state schema_table_state;
   void calc_md5(char *buffer);
   void set_underlying_merge();
@@ -752,6 +770,7 @@ struct TABLE_LIST
   void reinit_before_use(THD *thd);
   Item_subselect *containing_subselect();
 
+  void set_trg_event_type(const st_lex *lex);
 private:
   bool prep_check_option(THD *thd, uint8 check_opt_type);
   bool prep_where(THD *thd, Item **conds, bool no_where_clause);