MDEV-3873 & MDEV-3876 & MDEV-3912 : Wrong result (extra rows) with ALL subquery

from a MERGE view.

The problem was in the lost ability to be null for the table of a left join if it
is a view/derived table.

It hapenned because setup_table_map(), was called earlier then we merged
the view or derived.

Fixed by propagating new maybe_null flag during Item::update_used_tables().

Change in join_outer.test and join_outer_jcl6.test appeared because
IS NULL reported no used tables (i.e. constant) for argument which could not be
NULL and new maybe_null flag was propagated for IS NULL argument (Item_field)
because table the Item_field belonged to changed its maybe_null status.

1 files changed, 29 insertions, 19 deletions

diff --git a/sql/item_func.h b/sql/item_func.h
index 082c9b83296..3ab1fbad4e3 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -38,6 +38,8 @@ protected:
     0 means get this number from first argument
   */
   uint allowed_arg_cols;
+  /* maybe_null can't be changed by parameters or used table state */
+  bool persistent_maybe_null;
 public:
   uint arg_count;
   table_map used_tables_cache, not_null_tables_cache;
@@ -63,13 +65,13 @@ public:
   enum Type type() const { return FUNC_ITEM; }
   virtual enum Functype functype() const   { return UNKNOWN_FUNC; }
   Item_func(void):
-    allowed_arg_cols(1), arg_count(0)
+    allowed_arg_cols(1), persistent_maybe_null(0), arg_count(0)
   {
     with_sum_func= 0;
     with_field= 0;
   }
   Item_func(Item *a):
-    allowed_arg_cols(1), arg_count(1)
+    allowed_arg_cols(1), persistent_maybe_null(0), arg_count(1)
   {
     args= tmp_arg;
     args[0]= a;
@@ -77,7 +79,7 @@ public:
     with_field= a->with_field;
   }
   Item_func(Item *a,Item *b):
-    allowed_arg_cols(1), arg_count(2)
+    allowed_arg_cols(1), persistent_maybe_null(0), arg_count(2)
   {
     args= tmp_arg;
     args[0]= a; args[1]= b;
@@ -85,7 +87,7 @@ public:
     with_field= a->with_field || b->with_field;
   }
   Item_func(Item *a,Item *b,Item *c):
-    allowed_arg_cols(1)
+    allowed_arg_cols(1), persistent_maybe_null(0)
   {
     arg_count= 0;
     if ((args= (Item**) sql_alloc(sizeof(Item*)*3)))
@@ -97,7 +99,7 @@ public:
     }
   }
   Item_func(Item *a,Item *b,Item *c,Item *d):
-    allowed_arg_cols(1)
+    allowed_arg_cols(1), persistent_maybe_null(0)
   {
     arg_count= 0;
     if ((args= (Item**) sql_alloc(sizeof(Item*)*4)))
@@ -111,7 +113,7 @@ public:
     }
   }
   Item_func(Item *a,Item *b,Item *c,Item *d,Item* e):
-    allowed_arg_cols(1)
+    allowed_arg_cols(1), persistent_maybe_null(0)
   {
     arg_count= 5;
     if ((args= (Item**) sql_alloc(sizeof(Item*)*5)))
@@ -300,6 +302,11 @@ public:
     info.bool_function= &Item::restore_to_before_no_rows_in_result;
     walk(&Item::call_bool_func_processor, FALSE, (uchar*) &info);
   }
+  inline void set_persist_maybe_null(bool mb_null)
+  {
+    maybe_null= mb_null;
+    persistent_maybe_null= 1;
+  }
 };
 
 
@@ -506,7 +513,7 @@ public:
   }
   double val_real();
   enum_field_types field_type() const { return MYSQL_TYPE_DOUBLE; }
-  void fix_length_and_dec() { maybe_null= 1; }
+  void fix_length_and_dec() { set_persist_maybe_null(1); }
   const char *func_name() const { return "double_typecast"; }
   virtual void print(String *str, enum_query_type query_type);
 };
@@ -647,7 +654,7 @@ class Item_dec_func :public Item_real_func
   void fix_length_and_dec()
   {
     decimals=NOT_FIXED_DEC; max_length=float_length(decimals);
-    maybe_null=1;
+    set_persist_maybe_null(1);
   }
 };
 
@@ -971,7 +978,7 @@ public:
   Item_func_coercibility(Item *a) :Item_int_func(a) {}
   longlong val_int();
   const char *func_name() const { return "coercibility"; }
-  void fix_length_and_dec() { max_length=10; maybe_null= 0; }
+  void fix_length_and_dec() { max_length=10; set_persist_maybe_null(0); }
   table_map not_null_tables() const { return 0; }
 };
 
@@ -1132,7 +1139,7 @@ public:
   {}
   longlong val_int();
   const char *func_name() const { return "benchmark"; }
-  void fix_length_and_dec() { max_length=1; maybe_null=0; }
+  void fix_length_and_dec() { max_length=1; set_persist_maybe_null(0); }
   virtual void print(String *str, enum_query_type query_type);
   bool check_vcol_func_processor(uchar *int_arg) 
   {
@@ -1385,7 +1392,7 @@ public:
   double val_real() { DBUG_ASSERT(fixed == 1); null_value= 1; return 0.0; }
   longlong val_int() { DBUG_ASSERT(fixed == 1); null_value=1; return 0; }
   enum Item_result result_type () const { return STRING_RESULT; }
-  void fix_length_and_dec() { maybe_null=1; max_length=0; }
+  void fix_length_and_dec() { set_persist_maybe_null(1); max_length=0; }
 };
 
 #endif /* HAVE_DLOPEN */
@@ -1406,7 +1413,7 @@ class Item_func_get_lock :public Item_int_func
   Item_func_get_lock(Item *a,Item *b) :Item_int_func(a,b) {}
   longlong val_int();
   const char *func_name() const { return "get_lock"; }
-  void fix_length_and_dec() { max_length=1; maybe_null=1;}
+  void fix_length_and_dec() { max_length=1; set_persist_maybe_null(1);}
   bool check_vcol_func_processor(uchar *int_arg) 
   {
     return trace_unsupported_by_check_vcol_func_processor(func_name());
@@ -1420,7 +1427,7 @@ public:
   Item_func_release_lock(Item *a) :Item_int_func(a) {}
   longlong val_int();
   const char *func_name() const { return "release_lock"; }
-  void fix_length_and_dec() { max_length=1; maybe_null=1;}
+  void fix_length_and_dec() { max_length=1; set_persist_maybe_null(1);}
   bool check_vcol_func_processor(uchar *int_arg) 
   {
     return trace_unsupported_by_check_vcol_func_processor(func_name());
@@ -1437,7 +1444,7 @@ public:
   Item_master_pos_wait(Item *a,Item *b,Item *c) :Item_int_func(a,b,c) {}
   longlong val_int();
   const char *func_name() const { return "master_pos_wait"; }
-  void fix_length_and_dec() { max_length=21; maybe_null=1;}
+  void fix_length_and_dec() { max_length=21; set_persist_maybe_null(1);}
   bool check_vcol_func_processor(uchar *int_arg) 
   {
     return trace_unsupported_by_check_vcol_func_processor(func_name());
@@ -1653,7 +1660,8 @@ public:
   Item_func_inet_aton(Item *a) :Item_int_func(a) {}
   longlong val_int();
   const char *func_name() const { return "inet_aton"; }
-  void fix_length_and_dec() { decimals= 0; max_length= 21; maybe_null= 1; unsigned_flag= 1;}
+  void fix_length_and_dec()
+  { decimals= 0; max_length= 21; set_persist_maybe_null(1); unsigned_flag= 1; }
 };
 
 
@@ -1722,7 +1730,8 @@ public:
   Item_func_is_free_lock(Item *a) :Item_int_func(a) {}
   longlong val_int();
   const char *func_name() const { return "is_free_lock"; }
-  void fix_length_and_dec() { decimals=0; max_length=1; maybe_null=1;}
+  void fix_length_and_dec()
+  { decimals= 0; max_length= 1; set_persist_maybe_null(1); }
   bool check_vcol_func_processor(uchar *int_arg) 
   {
     return trace_unsupported_by_check_vcol_func_processor(func_name());
@@ -1736,7 +1745,8 @@ public:
   Item_func_is_used_lock(Item *a) :Item_int_func(a) {}
   longlong val_int();
   const char *func_name() const { return "is_used_lock"; }
-  void fix_length_and_dec() { decimals=0; max_length=10; maybe_null=1;}
+  void fix_length_and_dec()
+  { decimals= 0; max_length= 10; set_persist_maybe_null(1);}
   bool check_vcol_func_processor(uchar *int_arg) 
   {
     return trace_unsupported_by_check_vcol_func_processor(func_name());
@@ -1759,7 +1769,7 @@ public:
   Item_func_row_count() :Item_int_func() {}
   longlong val_int();
   const char *func_name() const { return "row_count"; }
-  void fix_length_and_dec() { decimals= 0; maybe_null=0; }
+  void fix_length_and_dec() { decimals= 0; set_persist_maybe_null(0); }
   bool check_vcol_func_processor(uchar *int_arg) 
   {
 
@@ -1893,7 +1903,7 @@ public:
   Item_func_found_rows() :Item_int_func() {}
   longlong val_int();
   const char *func_name() const { return "found_rows"; }
-  void fix_length_and_dec() { decimals= 0; maybe_null=0; }
+  void fix_length_and_dec() { decimals= 0; set_persist_maybe_null(0); }
   bool check_vcol_func_processor(uchar *int_arg) 
   {
     return trace_unsupported_by_check_vcol_func_processor(func_name());