void LEX::set_trg_event_type_for_tables()
{
  uint8 new_trg_event_map= 0;
  DBUG_ENTER("LEX::set_trg_event_type_for_tables");

  /*
    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.
  */

  switch (sql_command) {
  case SQLCOM_LOCK_TABLES:
  /*
    On a LOCK TABLE, all triggers must be pre-loaded for this TABLE_LIST
    when opening an associated TABLE.
  */
    new_trg_event_map= trg2bit(TRG_EVENT_INSERT) | trg2bit(TRG_EVENT_UPDATE) |
                       trg2bit(TRG_EVENT_DELETE);
    break;
  /*
    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:
  case SQLCOM_CREATE_SEQUENCE:
    new_trg_event_map|= trg2bit(TRG_EVENT_INSERT);
    break;
  /* Basic update and multi-update */
  case SQLCOM_UPDATE:                           /* fall through */
  case SQLCOM_UPDATE_MULTI:
    new_trg_event_map|= trg2bit(TRG_EVENT_UPDATE);
    break;
  /* Basic delete and multi-delete */
  case SQLCOM_DELETE:                           /* fall through */
  case SQLCOM_DELETE_MULTI:
    new_trg_event_map|= trg2bit(TRG_EVENT_DELETE);
    break;
  default:
    break;
  }

  switch (duplicates) {
  case DUP_UPDATE:
    new_trg_event_map|= trg2bit(TRG_EVENT_UPDATE);
    break;
  case DUP_REPLACE:
    new_trg_event_map|= trg2bit(TRG_EVENT_DELETE);
    break;
  case DUP_ERROR:
  default:
    break;
  }

  if (period_conditions.is_set())
  {
    switch (sql_command)
    {
    case SQLCOM_DELETE:
    case SQLCOM_UPDATE:
    case SQLCOM_REPLACE:
      new_trg_event_map |= trg2bit(TRG_EVENT_INSERT);
    default:
      break;
    }
  }


  /*
    Do not iterate over sub-selects, only the tables in the outermost
    SELECT_LEX can be modified, if any.
  */
  TABLE_LIST *tables= first_select_lex()->get_table_list();

  while (tables)
  {
    /*
      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>(tables->lock_type) >=
        static_cast<int>(TL_WRITE_ALLOW_WRITE))
      tables->trg_event_map= new_trg_event_map;
    tables= tables->next_local;
  }
  DBUG_VOID_RETURN;
}