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"

mysql-test/r/federated.result

@@ -1558,6 +1558,49 @@ id
 3
 4
 5
+DROP TABLE IF EXISTS federated.bug_17377_table;
+CREATE TABLE federated.bug_17377_table (
+`fld_cid` bigint(20) NOT NULL auto_increment,
+`fld_name` varchar(255) NOT NULL default '',
+`fld_parentid` bigint(20) NOT NULL default '0',
+`fld_delt` int(1) NOT NULL default '0',
+PRIMARY KEY (`fld_cid`),
+KEY `fld_parentid` (`fld_parentid`),
+KEY `fld_delt` (`fld_delt`),
+KEY `fld_cid` (`fld_cid`)
+) ENGINE=MyISAM;
+insert into federated.bug_17377_table( fld_name )
+values
+("Mats"), ("Sivert"), ("Sigvard"), ("Torgny"), ("Torkel");
+DROP TABLE IF EXISTS federated.t1;
+CREATE TABLE federated.t1 (
+`fld_cid` bigint(20) NOT NULL auto_increment,
+`fld_name` varchar(255) NOT NULL default '',
+`fld_parentid` bigint(20) NOT NULL default '0',
+`fld_delt` int(1) NOT NULL default '0',
+PRIMARY KEY (`fld_cid`),
+KEY `fld_parentid` (`fld_parentid`),
+KEY `fld_delt` (`fld_delt`),
+KEY `fld_cid` (`fld_cid`)
+) ENGINE=FEDERATED
+CONNECTION='mysql://root@127.0.0.1:SLAVE_PORT/federated/bug_17377_table';
+select * from federated.t1 where fld_parentid=0 and fld_delt=0
+order by fld_name;
+fld_cid	fld_name	fld_parentid	fld_delt
+1	Mats	0	0
+3	Sigvard	0	0
+2	Sivert	0	0
+4	Torgny	0	0
+5	Torkel	0	0
+select * from federated.t1 where fld_parentid=0 and fld_delt=0;
+fld_cid	fld_name	fld_parentid	fld_delt
+1	Mats	0	0
+2	Sivert	0	0
+3	Sigvard	0	0
+4	Torgny	0	0
+5	Torkel	0	0
+DROP TABLE federated.t1;
+DROP TABLE federated.bug_17377_table;
 DROP TABLE IF EXISTS federated.t1;
 DROP DATABASE IF EXISTS federated;
 DROP TABLE IF EXISTS federated.t1;

mysql-test/t/federated.test

@@ -1255,4 +1255,59 @@ INSERT INTO federated.t1 VALUES ();
 SELECT LAST_INSERT_ID();
 SELECT * FROM federated.t1;
 
+#
+# Bug#17377 Federated Engine returns wrong Data, always the rows
+#           with the highest ID
+#
+
+connection slave;
+
+--disable_warnings
+DROP TABLE IF EXISTS federated.bug_17377_table;
+--enable_warnings
+
+CREATE TABLE federated.bug_17377_table (
+`fld_cid` bigint(20) NOT NULL auto_increment,
+`fld_name` varchar(255) NOT NULL default '',
+`fld_parentid` bigint(20) NOT NULL default '0',
+`fld_delt` int(1) NOT NULL default '0',
+PRIMARY KEY (`fld_cid`),
+KEY `fld_parentid` (`fld_parentid`),
+KEY `fld_delt` (`fld_delt`),
+KEY `fld_cid` (`fld_cid`)
+) ENGINE=MyISAM;
+
+# Insert some test-data
+insert into federated.bug_17377_table( fld_name )
+values
+("Mats"), ("Sivert"), ("Sigvard"), ("Torgny"), ("Torkel");
+
+connection master;
+--disable_warnings
+DROP TABLE IF EXISTS federated.t1;
+--enable_warnings
+
+--replace_result $SLAVE_MYPORT SLAVE_PORT
+eval CREATE TABLE federated.t1 (
+`fld_cid` bigint(20) NOT NULL auto_increment,
+`fld_name` varchar(255) NOT NULL default '',
+`fld_parentid` bigint(20) NOT NULL default '0',
+`fld_delt` int(1) NOT NULL default '0',
+PRIMARY KEY (`fld_cid`),
+KEY `fld_parentid` (`fld_parentid`),
+KEY `fld_delt` (`fld_delt`),
+KEY `fld_cid` (`fld_cid`)
+) ENGINE=FEDERATED
+CONNECTION='mysql://root@127.0.0.1:$SLAVE_MYPORT/federated/bug_17377_table';
+
+select * from federated.t1 where fld_parentid=0 and fld_delt=0
+order by fld_name;
+
+select * from federated.t1 where fld_parentid=0 and fld_delt=0;
+
+DROP TABLE federated.t1;
+connection slave;
+DROP TABLE federated.bug_17377_table;
+
+
 source include/federated_cleanup.inc;

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 */
+  memcpy_fixed(&current_position, pos, sizeof(MYSQL_ROW_OFFSET));
   stored_result->current_row= 0;
   stored_result->data_cursor= current_position;
-    retval= rnd_next(buf);
-    DBUG_RETURN(retval);
-  }
-  DBUG_RETURN(0);
+  DBUG_RETURN(rnd_next(buf));
 }
 
 

sql/ha_federated.h

@@ -153,7 +153,6 @@ class ha_federated: public handler
   FEDERATED_SHARE *share;    /* Shared lock info */
   MYSQL *mysql; /* MySQL connection */
   MYSQL_RES *stored_result;
-  bool scan_flag;
   uint ref_length;
   uint fetch_num; // stores the fetch num
   MYSQL_ROW_OFFSET current_position;  // Current position used by ::position()