BUG#849776: Wrong result with semijoin + "Impossible where"

- Provide fix_after_pullout() function for Item_in_optimizer and other Item_XXX classes (basically, all of them
  that have eval_not_null_tables, which means they have special rules for calculating not_null_tables_cache value)

mysql-test/r/subselect_sj.result

@@ -1903,4 +1903,21 @@ a	a
 EXECUTE st1;
 a	a
 DROP TABLE t1, t2, t3;
+#
+# BUG#849776: Wrong result with semijoin + "Impossible where"
+#
+CREATE TABLE t1 ( b varchar(1), a integer) ;
+INSERT INTO t1 VALUES ('z',8);
+CREATE TABLE t2 ( a integer, b varchar(1)) ;
+CREATE TABLE t4 ( a integer, b varchar(1)) ;
+CREATE TABLE t5 ( a integer) ;
+INSERT INTO t5 VALUES (8);
+select * from t5 where (a) in (
+SELECT t1.a 
+FROM t1 LEFT JOIN t2 ON t1.a = t2.a
+WHERE t2.b NOT IN (SELECT t4.b FROM t4 WHERE t4.b < t1.b)
+);
+a
+8
+DROP TABLE t1, t2, t4, t5;
 set optimizer_switch=@subselect_sj_tmp;

mysql-test/r/subselect_sj_jcl6.result

@@ -1914,6 +1914,23 @@ a	a
 EXECUTE st1;
 a	a
 DROP TABLE t1, t2, t3;
+#
+# BUG#849776: Wrong result with semijoin + "Impossible where"
+#
+CREATE TABLE t1 ( b varchar(1), a integer) ;
+INSERT INTO t1 VALUES ('z',8);
+CREATE TABLE t2 ( a integer, b varchar(1)) ;
+CREATE TABLE t4 ( a integer, b varchar(1)) ;
+CREATE TABLE t5 ( a integer) ;
+INSERT INTO t5 VALUES (8);
+select * from t5 where (a) in (
+SELECT t1.a 
+FROM t1 LEFT JOIN t2 ON t1.a = t2.a
+WHERE t2.b NOT IN (SELECT t4.b FROM t4 WHERE t4.b < t1.b)
+);
+a
+8
+DROP TABLE t1, t2, t4, t5;
 set optimizer_switch=@subselect_sj_tmp;
 #
 # BUG#49129: Wrong result with IN-subquery with join_cache_level=6 and firstmatch=off

mysql-test/t/subselect_sj.test

@@ -1735,5 +1735,26 @@ EXECUTE st1;
 
 DROP TABLE t1, t2, t3;
 
+--echo #
+--echo # BUG#849776: Wrong result with semijoin + "Impossible where"
+--echo #
+CREATE TABLE t1 ( b varchar(1), a integer) ;
+INSERT INTO t1 VALUES ('z',8);
+
+CREATE TABLE t2 ( a integer, b varchar(1)) ;
+
+CREATE TABLE t4 ( a integer, b varchar(1)) ;
+
+CREATE TABLE t5 ( a integer) ;
+INSERT INTO t5 VALUES (8);
+
+select * from t5 where (a) in (
+  SELECT t1.a 
+  FROM t1 LEFT JOIN t2 ON t1.a = t2.a
+  WHERE t2.b NOT IN (SELECT t4.b FROM t4 WHERE t4.b < t1.b)
+);
+
+DROP TABLE t1, t2, t4, t5;
+
 # The following command must be the last one the file 
 set optimizer_switch=@subselect_sj_tmp;

sql/item_cmpfunc.cc

@@ -1405,6 +1405,16 @@ bool Item_in_optimizer::is_top_level_item()
 }
 
 
+void Item_in_optimizer::fix_after_pullout(st_select_lex *new_parent, Item **ref)
+{
+  /* This will re-calculate attributes of our Item_in_subselect: */
+  Item_bool_func::fix_after_pullout(new_parent, ref);
+
+  /* Then, re-calculate not_null_tables_cache: */
+  eval_not_null_tables(NULL);
+}
+
+
 bool Item_in_optimizer::eval_not_null_tables(uchar *opt_arg)
 {
   not_null_tables_cache= 0;
@@ -2136,6 +2146,14 @@ bool Item_func_between::eval_not_null_tables(uchar *opt_arg)
 }  
 
 
+void Item_func_between::fix_after_pullout(st_select_lex *new_parent, Item **ref)
+{
+  /* This will re-calculate attributes of the arguments */
+  Item_func_opt_neg::fix_after_pullout(new_parent, ref);
+  /* Then, re-calculate not_null_tables_cache according to our special rules */
+  eval_not_null_tables(NULL);
+}
+
 void Item_func_between::fix_length_and_dec()
 {
   THD *thd= current_thd;
@@ -2516,6 +2534,16 @@ Item_func_if::eval_not_null_tables(uchar *opt_arg)
   return 0;
 }
 
+
+void Item_func_if::fix_after_pullout(st_select_lex *new_parent, Item **ref)
+{
+  /* This will re-calculate attributes of the arguments */
+  Item_func::fix_after_pullout(new_parent, ref);
+  /* Then, re-calculate not_null_tables_cache according to our special rules */
+  eval_not_null_tables(NULL);
+}
+
+
 void
 Item_func_if::fix_length_and_dec()
 {
@@ -3760,6 +3788,14 @@ Item_func_in::eval_not_null_tables(uchar *opt_arg)
 }
 
 
+void Item_func_in::fix_after_pullout(st_select_lex *new_parent, Item **ref)
+{
+  /* This will re-calculate attributes of the arguments */
+  Item_func_opt_neg::fix_after_pullout(new_parent, ref);
+  /* Then, re-calculate not_null_tables_cache according to our special rules */
+  eval_not_null_tables(NULL);
+}
+
 static int srtcmp_in(CHARSET_INFO *cs, const String *x,const String *y)
 {
   return cs->coll->strnncollsp(cs,

sql/item_cmpfunc.h

@@ -262,6 +262,7 @@ public:
   virtual void get_cache_parameters(List<Item> &parameters);
   bool is_top_level_item();
   bool eval_not_null_tables(uchar *opt_arg);
+  void fix_after_pullout(st_select_lex *new_parent, Item **ref);
 };
 
 class Comp_creator
@@ -674,6 +675,7 @@ public:
   CHARSET_INFO *compare_collation() { return cmp_collation.collation; }
   uint decimal_precision() const { return 1; }
   bool eval_not_null_tables(uchar *opt_arg);
+  void fix_after_pullout(st_select_lex *new_parent, Item **ref);
 };
 
 
@@ -775,6 +777,7 @@ public:
   uint decimal_precision() const;
   const char *func_name() const { return "if"; }
   bool eval_not_null_tables(uchar *opt_arg);
+  void fix_after_pullout(st_select_lex *new_parent, Item **ref);
 };
 
 
@@ -1313,6 +1316,7 @@ public:
   bool is_bool_func() { return 1; }
   CHARSET_INFO *compare_collation() { return cmp_collation.collation; }
   bool eval_not_null_tables(uchar *opt_arg);
+  void fix_after_pullout(st_select_lex *new_parent, Item **ref);
 };
 
 class cmp_item_row :public cmp_item

sql/item_row.cc

@@ -149,11 +149,13 @@ void Item_row::fix_after_pullout(st_select_lex *new_parent, Item **ref)
 {
   used_tables_cache= 0;
   const_item_cache= 1;
+  not_null_tables_cache= 0;
   for (uint i= 0; i < arg_count; i++)
   {
     items[i]->fix_after_pullout(new_parent, &items[i]);
     used_tables_cache|= items[i]->used_tables();
     const_item_cache&= items[i]->const_item();
+    not_null_tables_cache|= items[i]->not_null_tables();
   }
 }
 

sql/item_subselect.cc

@@ -2477,8 +2477,7 @@ void Item_in_subselect::fix_after_pullout(st_select_lex *new_parent, Item **ref)
 {
   left_expr->fix_after_pullout(new_parent, &left_expr);
   Item_subselect::fix_after_pullout(new_parent, ref);
-  //psergey-todo: the above looks odd, why don't we 'aggregate' left_expr with
-  //the rest?
+  used_tables_cache |= left_expr->used_tables();
 }
 
 void Item_in_subselect::update_used_tables()