BUG#906357: Incorrect result with outer join and full text match

- The problem was that const-table-reading code would try to evaluate MATCH()
  before init_ftfuncs() was called. 
- Fixed by making MATCH function "expensive" so that nobody tries to evaluate it
  at optimization phase.

mysql-test/r/fulltext_left_join.result

@@ -97,3 +97,17 @@ INSERT INTO t2(b,c) VALUES(2,'castle'),(3,'castle');
 SELECT * FROM t1 LEFT JOIN t2 ON a=b WHERE MATCH(c) AGAINST('+castle' IN BOOLEAN MODE);
 a	b	c
 DROP TABLE t1, t2;
+#
+# BUG#906357: Incorrect result with outer join and full text match
+# 
+CREATE TABLE t1(f1 VARCHAR(6) NOT NULL, FULLTEXT KEY(f1), UNIQUE(f1));
+INSERT INTO t1 VALUES ('test');
+CREATE TABLE t2(f2 VARCHAR(6) NOT NULL, FULLTEXT KEY(f2), UNIQUE(f2));
+INSERT INTO t2 VALUES ('test');
+SELECT * FROM t2 LEFT OUTER JOIN t1 ON (MATCH(f1) against (""));
+f2	f1
+test	NULL
+SELECT * FROM t1 RIGHT OUTER JOIN t2 ON (MATCH(f1) against (""));
+f1	f2
+NULL	test
+DROP table t1,t2;

mysql-test/r/fulltext_order_by.result

@@ -46,10 +46,10 @@ a	MATCH (message) AGAINST ('steve' IN BOOLEAN MODE)
 7	1
 SELECT a, FORMAT(MATCH (message) AGAINST ('steve'),6) as rel FROM t1 ORDER BY rel;
 a	rel
-1	0.000000
-2	0.000000
 3	0.000000
+1	0.000000
 5	0.000000
+2	0.000000
 6	0.000000
 7	0.895690
 4	0.905873

mysql-test/t/fulltext_left_join.test

@@ -98,3 +98,16 @@ INSERT INTO t1 VALUES(1);
 INSERT INTO t2(b,c) VALUES(2,'castle'),(3,'castle');
 SELECT * FROM t1 LEFT JOIN t2 ON a=b WHERE MATCH(c) AGAINST('+castle' IN BOOLEAN MODE);
 DROP TABLE t1, t2;
+
+--echo #
+--echo # BUG#906357: Incorrect result with outer join and full text match
+--echo # 
+CREATE TABLE t1(f1 VARCHAR(6) NOT NULL, FULLTEXT KEY(f1), UNIQUE(f1));
+INSERT INTO t1 VALUES ('test');
+
+CREATE TABLE t2(f2 VARCHAR(6) NOT NULL, FULLTEXT KEY(f2), UNIQUE(f2));
+INSERT INTO t2 VALUES ('test');
+SELECT * FROM t2 LEFT OUTER JOIN t1 ON (MATCH(f1) against (""));
+SELECT * FROM t1 RIGHT OUTER JOIN t2 ON (MATCH(f1) against (""));
+
+DROP table t1,t2;

sql/item_func.h

@@ -1676,6 +1676,7 @@ public:
     table= 0;           // required by Item_func_match::eq()
     DBUG_VOID_RETURN;
   }
+  bool is_expensive_processor(uchar *arg) { return TRUE; }
   enum Functype functype() const { return FT_FUNC; }
   const char *func_name() const { return "match"; }
   void update_used_tables() {}