diff --git a/mysql-test/r/fulltext_order_by.result b/mysql-test/r/fulltext_order_by.result
index bc466b5aba7..bd3e79ec5c2 100644
--- a/mysql-test/r/fulltext_order_by.result
+++ b/mysql-test/r/fulltext_order_by.result
@@ -126,7 +126,7 @@ group by
 a.text, b.id, b.betreff
 order by 
 match(b.betreff) against ('+abc' in boolean mode) desc;
-ERROR 42S22: Unknown column 'b.betreff' in 'order clause'
+ERROR 42000: Incorrect usage/placement of 'MATCH()'
 select a.text, b.id, b.betreff
 from 
 t2 a inner join t3 b on a.id = b.forum inner join
@@ -142,7 +142,7 @@ where
 match(c.beitrag) against ('+abc' in boolean mode)
 order by 
 match(b.betreff) against ('+abc' in boolean mode) desc;
-ERROR 42S22: Unknown column 'b.betreff' in 'order clause'
+ERROR 42000: Incorrect usage/placement of 'MATCH()'
 select a.text, b.id, b.betreff
 from 
 t2 a inner join t3 b on a.id = b.forum inner join
@@ -158,7 +158,7 @@ where
 match(c.beitrag) against ('+abc' in boolean mode)
 order by 
 match(betreff) against ('+abc' in boolean mode) desc;
-text	id	betreff
+ERROR 42000: Incorrect usage/placement of 'MATCH()'
 (select b.id, b.betreff from t3 b) union 
 (select b.id, b.betreff from t3 b) 
 order by match(betreff) against ('+abc' in boolean mode) desc;
diff --git a/mysql-test/r/union.result b/mysql-test/r/union.result
index 44a3812725a..dce32d2ced4 100644
--- a/mysql-test/r/union.result
+++ b/mysql-test/r/union.result
@@ -1588,3 +1588,66 @@ Warnings:
 Note	1003	select '0' AS `a` from `test`.`t1` union select '0' AS `a` from `test`.`t1` order by `a`
 DROP TABLE t1;
 End of 5.0 tests
+# 
+# Bug #49734: Crash on EXPLAIN EXTENDED UNION ... ORDER BY 
+#   <any non-const-function>
+# 
+CREATE TABLE t1 (a VARCHAR(10), FULLTEXT KEY a (a));
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (b INT);
+INSERT INTO t2 VALUES (1),(2);
+# Should not crash
+EXPLAIN EXTENDED
+SELECT * FROM t1 UNION SELECT * FROM t1 ORDER BY a + 12;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+2	UNION	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+NULL	UNION RESULT	<union1,2>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	Using filesort
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` union select `test`.`t1`.`a` AS `a` from `test`.`t1` order by (`a` + 12)
+# Should not crash
+SELECT * FROM t1 UNION SELECT * FROM t1 ORDER BY a + 12;
+a
+1
+2
+# Should not crash
+EXPLAIN EXTENDED
+SELECT * FROM t1 UNION SELECT * FROM t1
+ORDER BY MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE);
+ERROR 42000: Incorrect usage/placement of 'MATCH()'
+# Should not crash
+SELECT * FROM t1 UNION SELECT * FROM t1
+ORDER BY MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE);
+ERROR 42000: Incorrect usage/placement of 'MATCH()'
+# Should not crash
+(SELECT * FROM t1) UNION (SELECT * FROM t1)
+ORDER BY MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE);
+a
+1
+2
+# Should not crash
+EXPLAIN EXTENDED
+SELECT * FROM t1 UNION SELECT * FROM t1
+ORDER BY (SELECT a FROM t2 WHERE b = 12);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+2	UNION	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
+3	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+NULL	UNION RESULT	<union1,2>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	Using filesort
+Warnings:
+Note	1276	Field or reference 'test.t1.a' of SELECT #3 was resolved in SELECT #2
+Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` union select `test`.`t1`.`a` AS `a` from `test`.`t1` order by (select `test`.`t1`.`a` AS `a` from `test`.`t2` where (`test`.`t2`.`b` = 12))
+# Should not crash
+SELECT * FROM t1 UNION SELECT * FROM t1
+ORDER BY (SELECT a FROM t2 WHERE b = 12);
+a
+1
+2
+# Should not crash
+SELECT * FROM t2 UNION SELECT * FROM t2
+ORDER BY (SELECT * FROM t1 WHERE MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE));
+b
+1
+2
+DROP TABLE t1,t2;
+End of 5.1 tests
diff --git a/mysql-test/t/fulltext_order_by.test b/mysql-test/t/fulltext_order_by.test
index 074aefbf943..814cd4a5954 100644
--- a/mysql-test/t/fulltext_order_by.test
+++ b/mysql-test/t/fulltext_order_by.test
@@ -80,7 +80,7 @@ CREATE TABLE t3 (
   FULLTEXT KEY betreff (betreff)
 ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=996 ;
 
---error 1054
+--error ER_CANT_USE_OPTION_HERE
 select a.text, b.id, b.betreff
 from 
   t2 a inner join t3 b on a.id = b.forum inner join
@@ -100,7 +100,7 @@ group by
 order by 
   match(b.betreff) against ('+abc' in boolean mode) desc;
   
---error 1054
+--error ER_CANT_USE_OPTION_HERE
 select a.text, b.id, b.betreff
 from 
   t2 a inner join t3 b on a.id = b.forum inner join
@@ -117,6 +117,7 @@ where
 order by 
   match(b.betreff) against ('+abc' in boolean mode) desc;
 
+--error ER_CANT_USE_OPTION_HERE
 select a.text, b.id, b.betreff
 from 
   t2 a inner join t3 b on a.id = b.forum inner join
diff --git a/mysql-test/t/union.test b/mysql-test/t/union.test
index ec169838d59..91fc9546bbe 100644
--- a/mysql-test/t/union.test
+++ b/mysql-test/t/union.test
@@ -1102,3 +1102,56 @@ DROP TABLE t1;
 
 
 --echo End of 5.0 tests
+
+
+--echo # 
+--echo # Bug #49734: Crash on EXPLAIN EXTENDED UNION ... ORDER BY 
+--echo #   <any non-const-function>
+--echo # 
+
+CREATE TABLE t1 (a VARCHAR(10), FULLTEXT KEY a (a));
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (b INT);
+INSERT INTO t2 VALUES (1),(2);
+
+--echo # Should not crash
+EXPLAIN EXTENDED
+SELECT * FROM t1 UNION SELECT * FROM t1 ORDER BY a + 12;
+
+--echo # Should not crash
+SELECT * FROM t1 UNION SELECT * FROM t1 ORDER BY a + 12;
+
+
+--echo # Should not crash
+--error ER_CANT_USE_OPTION_HERE
+EXPLAIN EXTENDED
+SELECT * FROM t1 UNION SELECT * FROM t1
+  ORDER BY MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE);
+
+--echo # Should not crash
+--error ER_CANT_USE_OPTION_HERE
+SELECT * FROM t1 UNION SELECT * FROM t1
+  ORDER BY MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE);
+
+--echo # Should not crash
+(SELECT * FROM t1) UNION (SELECT * FROM t1)
+  ORDER BY MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE);
+
+
+--echo # Should not crash
+EXPLAIN EXTENDED
+SELECT * FROM t1 UNION SELECT * FROM t1
+  ORDER BY (SELECT a FROM t2 WHERE b = 12);
+
+--echo # Should not crash
+SELECT * FROM t1 UNION SELECT * FROM t1
+  ORDER BY (SELECT a FROM t2 WHERE b = 12);
+
+--echo # Should not crash
+SELECT * FROM t2 UNION SELECT * FROM t2
+  ORDER BY (SELECT * FROM t1 WHERE MATCH(a) AGAINST ('+abc' IN BOOLEAN MODE));
+
+DROP TABLE t1,t2;
+
+
+--echo End of 5.1 tests
diff --git a/sql/item.h b/sql/item.h
index b97808ac87f..8f0e5874f3f 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -967,6 +967,23 @@ public:
     return FALSE;
   }
 
+  /**
+    Find a function of a given type
+
+    @param   arg     the function type to search (enum Item_func::Functype)
+    @return
+      @retval TRUE   the function type we're searching for is found
+      @retval FALSE  the function type wasn't found
+
+    @description
+      This function can be used (together with Item::walk()) to find functions
+      in an item tree fragment.
+  */
+  virtual bool find_function_processor (uchar *arg)
+  {
+    return FALSE;
+  }
+
   /*
     For SP local variable returns pointer to Item representing its
     current value and pointer to current Item otherwise.
diff --git a/sql/item_func.h b/sql/item_func.h
index 259316b0c41..71168c64e4b 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -212,6 +212,11 @@ public:
   {
     return has_timestamp_args();
   }
+
+  virtual bool find_function_processor (uchar *arg)
+  {
+    return functype() == *(Functype *) arg;
+  }
 };
 
 
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 6383fe63012..d50bb888850 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -519,7 +519,7 @@ JOIN::prepare(Item ***rref_pointer_array,
     thd->lex->allow_sum_func= save_allow_sum_func;
   }
 
-  if (!thd->lex->view_prepare_mode)
+  if (!thd->lex->view_prepare_mode && !(select_options & SELECT_DESCRIBE))
   {
     Item_subselect *subselect;
     /* Is it subselect? */
diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index cbf94ad7181..1760670f9c8 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -335,6 +335,35 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
       }
     }
     
+    /*
+      Disable the usage of fulltext searches in the last union branch.
+      This is a temporary 5.x limitation because of the way the fulltext
+      search functions are handled by the optimizer.
+      This is manifestation of the more general problems of "taking away"
+      parts of a SELECT statement post-fix_fields(). This is generally not
+      doable since various flags are collected in various places (e.g. 
+      SELECT_LEX) that carry information about the presence of certain 
+      expressions or constructs in the parts of the query.
+      When part of the query is taken away it's not clear how to "divide" 
+      the meaning of these accumulated flags and what to carry over to the
+      recipient query (SELECT_LEX).
+    */
+    if (global_parameters->ftfunc_list->elements && 
+        global_parameters->order_list.elements &&
+        global_parameters != fake_select_lex)
+    {
+      ORDER *ord;
+      Item_func::Functype ft=  Item_func::FT_FUNC;
+      for (ord= (ORDER*)global_parameters->order_list.first; ord; ord= ord->next)
+        if ((*ord->item)->walk (&Item::find_function_processor, FALSE, 
+                                (uchar *) &ft))
+        {
+          my_error (ER_CANT_USE_OPTION_HERE, MYF(0), "MATCH()");
+          goto err;
+        }
+    }
+
+
     create_options= (first_sl->options | thd_arg->options |
                      TMP_TABLE_ALL_COLUMNS);
     /*
@@ -669,7 +698,7 @@ bool st_select_lex_unit::cleanup()
     {
       ORDER *ord;
       for (ord= (ORDER*)global_parameters->order_list.first; ord; ord= ord->next)
-        (*ord->item)->cleanup();
+        (*ord->item)->walk (&Item::cleanup_processor, 0, 0);
     }
   }