Bug#17377 Federated Engine returns wrong Data, always the rows with the highest ID

 - Always make rnd_pos reposition the cursor in the fetched result set.


mysql-test/r/federated.result:
  Update test result
mysql-test/t/federated.test:
  Add test for bug#17377
sql/ha_federated.cc:
  Remove the "scan_flag" variable. rnd_pos should always move to a new position in the result set. 
  The "scan" flag in rnd_init will protect from the old result set being 
  closed and a new fecthed. I think the "scan_flag" was added before check of the "scan" argument in rnd_init was added.
sql/ha_federated.h:
  Remove class variable "scan_flag"

1 files changed, 9 insertions, 20 deletions

diff --git a/sql/ha_federated.cc b/sql/ha_federated.cc
index af7c987e477..c6d5c77803b 100644
--- a/sql/ha_federated.cc
+++ b/sql/ha_federated.cc
@@ -740,7 +740,7 @@ error:
 
 ha_federated::ha_federated(TABLE *table_arg)
   :handler(&federated_hton, table_arg),
-  mysql(0), stored_result(0), scan_flag(0),
+  mysql(0), stored_result(0),
   ref_length(sizeof(MYSQL_ROW_OFFSET)), current_position(0)
 {}
 
@@ -2243,7 +2243,7 @@ int ha_federated::rnd_init(bool scan)
     containing the correct record, hence update the wrong row!
 
   */
-  scan_flag= scan;
+
   if (scan)
   {
     DBUG_PRINT("info", ("share->select_query %s", share->select_query));
@@ -2365,24 +2365,13 @@ void ha_federated::position(const byte *record)
 int ha_federated::rnd_pos(byte *buf, byte *pos)
 {
   DBUG_ENTER("ha_federated::rnd_pos");
-  /*
-    we do not need to do any of this if there has been a scan performed
-    already, or if this is an update and index_read_idx already has a result
-    set in which to build it's update query from
-  */
-  if (scan_flag)
-  {
-    int retval;
-    statistic_increment(table->in_use->status_var.ha_read_rnd_count,
-                        &LOCK_status);
-    memcpy_fixed(&current_position, pos, sizeof(MYSQL_ROW_OFFSET));  // pos
-    /* is not aligned */
-    stored_result->current_row= 0;
-    stored_result->data_cursor= current_position;
-    retval= rnd_next(buf);
-    DBUG_RETURN(retval);
-  }
-  DBUG_RETURN(0);
+
+  statistic_increment(table->in_use->status_var.ha_read_rnd_count,
+                      &LOCK_status);
+  memcpy_fixed(&current_position, pos, sizeof(MYSQL_ROW_OFFSET));
+  stored_result->current_row= 0;
+  stored_result->data_cursor= current_position;
+  DBUG_RETURN(rnd_next(buf));
 }