Description:
This patch is for send updating(deleting) sql to remote server directly threw FDW type storage engine like Spider.
Detail:
Add handler::ha_direct_update_rows_init(), handler::ha_direct_update_rows(), handler::ha_direct_update_row_binlog(), handler::ha_direct_delete_rows_init(), handler::ha_direct_delete_rows() and handler::
+ha_direct_delete_row_binlog() for direct updating(deleting).
handler::ha_direct_update_rows_init() and handler::ha_direct_delete_rows_init() are used for asking to handler "is this sql possible to do direct updating(deleting)?".
handler::ha_direct_update_rows() and handler::ha_direct_delete_rows() are used for executing updating(deleting).
handler::ha_direct_update_row_binlog() and handler::ha_direct_delete_row_binlog() are used for writing row base binary log.