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, 15 insertions, 13 deletions

diff --git a/sql/item_strfunc.h b/sql/item_strfunc.h
index fc4e888e6ea..e3b040a2e55 100644
--- a/sql/item_strfunc.h
+++ b/sql/item_strfunc.h
@@ -319,7 +319,7 @@ public:
   String *val_str(String *);
   void fix_length_and_dec()
   {
-    maybe_null=1;
+    set_persist_maybe_null(1);
     /* 9 = MAX ((8- (arg_len % 8)) + 1) */
     max_length = args[0]->max_length + 9;
   }
@@ -335,7 +335,7 @@ public:
   String *val_str(String *);
   void fix_length_and_dec()
   {
-    maybe_null=1;
+    set_persist_maybe_null(1);
     /* 9 = MAX ((8- (arg_len % 8)) + 1) */
     max_length = args[0]->max_length - 9;
   }
@@ -361,7 +361,7 @@ public:
     constructor_helper();
   }
   String *val_str(String *);
-  void fix_length_and_dec() { maybe_null=1; max_length = 13; }
+  void fix_length_and_dec() { set_persist_maybe_null(1); max_length = 13; }
   const char *func_name() const { return "encrypt"; }
   bool check_vcol_func_processor(uchar *int_arg) 
   {
@@ -431,7 +431,7 @@ public:
   void fix_length_and_dec()
   {
     max_length= MAX_FIELD_NAME * system_charset_info->mbmaxlen;
-    maybe_null=1;
+    set_persist_maybe_null(1);
   }
   const char *func_name() const { return "database"; }
   const char *fully_qualified_func_name() const { return "database()"; }
@@ -607,7 +607,7 @@ public:
   {
     collation.set(default_charset());
     max_length=64;
-    maybe_null= 1;
+    set_persist_maybe_null(1);
   }
 };
 
@@ -634,7 +634,7 @@ public:
   Item_func_unhex(Item *a) :Item_str_func(a) 
   { 
     /* there can be bad hex strings */
-    maybe_null= 1; 
+    set_persist_maybe_null(1);
   }
   const char *func_name() const { return "unhex"; }
   String *val_str(String *);
@@ -680,7 +680,7 @@ public:
   void fix_length_and_dec()
   {
     collation.set(&my_charset_bin, DERIVATION_COERCIBLE);
-    maybe_null=1;
+    set_persist_maybe_null(1);
     max_length=MAX_BLOB_WIDTH;
   }
   bool check_vcol_func_processor(uchar *int_arg) 
@@ -713,7 +713,7 @@ public:
   { 
     decimals= 0; 
     max_length= 3 * 8 + 7; 
-    maybe_null= 1;
+    set_persist_maybe_null(1);
   }
 };
 
@@ -804,7 +804,7 @@ public:
   {
      collation.set(system_charset_info);
      max_length= 64 * collation.collation->mbmaxlen; // should be enough
-     maybe_null= 0;
+     set_persist_maybe_null(0);
   };
   table_map not_null_tables() const { return 0; }
 };
@@ -819,7 +819,7 @@ public:
   {
      collation.set(system_charset_info);
      max_length= 64 * collation.collation->mbmaxlen; // should be enough
-     maybe_null= 0;
+     set_persist_maybe_null(0);
   };
   table_map not_null_tables() const { return 0; }
 };
@@ -865,7 +865,8 @@ class Item_func_uncompress: public Item_str_func
   String buffer;
 public:
   Item_func_uncompress(Item *a): Item_str_func(a){}
-  void fix_length_and_dec(){ maybe_null= 1; max_length= MAX_BLOB_WIDTH; }
+  void fix_length_and_dec()
+  { set_persist_maybe_null(1); max_length= MAX_BLOB_WIDTH; }
   const char *func_name() const{return "uncompress";}
   String *val_str(String *) ZLIB_DEPENDED_FUNCTION
 };
@@ -937,7 +938,7 @@ public:
     max_length= MAX_DYNAMIC_COLUMN_LENGTH;
   }
   void fix_length_and_dec()
-  { maybe_null= 1; }
+  { set_persist_maybe_null(1); }
   /* Mark that collation can change between calls */
   bool dynamic_result() { return 1; }
 
@@ -956,7 +957,8 @@ class Item_func_dyncol_list: public Item_str_func
 {
 public:
   Item_func_dyncol_list(Item *str) :Item_str_func(str) {};
-  void fix_length_and_dec() { maybe_null= 1; max_length= MAX_BLOB_WIDTH; };
+  void fix_length_and_dec()
+  { set_persist_maybe_null(1); max_length= MAX_BLOB_WIDTH; };
   const char *func_name() const{ return "column_list"; }
   String *val_str(String *);
 };