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From:Guilhem Bichot Date:December 2 2010 1:38pm
Subject:bzr commit into mysql-5.5-bugteam branch (guilhem:3125) Bug#57932
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#At file:///home/mysql_src/bzrrepos_new/5.5-bugteam/ based on revid:guilhem@stripped

 3125 Guilhem Bichot	2010-12-02
      Fix for Bug#57932 "query with avg returns incorrect results":
      when there was one NULL value, AVG(DISTINCT) could forget about other values.
      Fourth possible patch suggested by Joro.
     @ mysql-test/r/func_group.result
        before the code fix, both SELECTs would return NULL
     @ sql/item_sum.cc
        This time the fix is to let the aggregator tell whether the value
        it just saw was NULL. The aggregator knows where to get the info
        thanks to virtual functions. Item_sum_sum::add() now asks
        the aggregator. Item_sum_avg() also asks the aggregator
        and then knows it shouldn't increment "count".

    modified:
      mysql-test/r/func_group.result
      mysql-test/t/func_group.test
      sql/item_sum.cc
      sql/item_sum.h
=== modified file 'mysql-test/r/func_group.result'
--- a/mysql-test/r/func_group.result	2010-09-10 18:48:13 +0000
+++ b/mysql-test/r/func_group.result	2010-12-02 13:38:12 +0000
@@ -1746,3 +1746,18 @@ MAX(c1)	MIN(c1)
 -00:00:01	-00:00:01
 DROP TABLE t1;
 # End of the bug#56120
+#
+# Bug#57932 "query with AVG(DISTINCT) returns NULL if last
+# aggregated value was NULL"
+#
+CREATE TABLE t1 (col_int_nokey int(11));
+INSERT INTO t1 VALUES (7),(8),(NULL);
+SELECT AVG(DISTINCT col_int_nokey) FROM t1;
+AVG(DISTINCT col_int_nokey)
+7.5000
+SELECT AVG(DISTINCT outr.col_int_nokey) FROM t1 AS outr LEFT JOIN t1 AS outr2 ON
+outr.col_int_nokey = outr2.col_int_nokey;
+AVG(DISTINCT outr.col_int_nokey)
+7.5000
+DROP TABLE t1;
+# End of the bug#56120

=== modified file 'mysql-test/t/func_group.test'
--- a/mysql-test/t/func_group.test	2010-09-10 18:48:13 +0000
+++ b/mysql-test/t/func_group.test	2010-12-02 13:38:12 +0000
@@ -1118,3 +1118,14 @@ SELECT MAX(c1),MIN(c1) FROM t1;
 DROP TABLE t1;
 --echo # End of the bug#56120
 
+--echo #
+--echo # Bug#57932 "query with AVG(DISTINCT) returns NULL if last
+--echo # aggregated value was NULL"
+--echo #
+CREATE TABLE t1 (col_int_nokey int(11));
+INSERT INTO t1 VALUES (7),(8),(NULL);
+SELECT AVG(DISTINCT col_int_nokey) FROM t1;
+SELECT AVG(DISTINCT outr.col_int_nokey) FROM t1 AS outr LEFT JOIN t1 AS outr2 ON
+outr.col_int_nokey = outr2.col_int_nokey;
+DROP TABLE t1;
+--echo # End of the bug#56120

=== modified file 'sql/item_sum.cc'
--- a/sql/item_sum.cc	2010-09-02 13:57:59 +0000
+++ b/sql/item_sum.cc	2010-12-02 13:38:12 +0000
@@ -1325,27 +1325,11 @@ void Item_sum_sum::fix_length_and_dec()
 bool Item_sum_sum::add()
 {
   DBUG_ENTER("Item_sum_sum::add");
-  bool arg_is_null;
   if (hybrid_type == DECIMAL_RESULT)
   {
-    my_decimal value, *val;
-    if (aggr->use_distinct_values)
-    {
-      /* 
-        We are aggregating distinct rows. Get the value from the distinct 
-        table pointer
-      */
-      Aggregator_distinct *daggr= (Aggregator_distinct *)aggr;
-      val= daggr->table->field[0]->val_decimal (&value);
-      arg_is_null= daggr->table->field[0]->is_null();
-    }
-    else
-    {
-      /* non-distinct aggregation */
-      val= args[0]->val_decimal(&value);
-      arg_is_null= args[0]->null_value;
-    }
-    if (!arg_is_null)
+    my_decimal value;
+    const my_decimal *val= aggr->arg_val_decimal(&value);
+    if (!aggr->arg_is_null())
     {
       my_decimal_add(E_DEC_FATAL_ERROR, dec_buffs + (curr_dec_buff^1),
                      val, dec_buffs + curr_dec_buff);
@@ -1355,25 +1339,8 @@ bool Item_sum_sum::add()
   }
   else
   {
-    double val;
-    if (aggr->use_distinct_values)
-    {
-      /* 
-        We are aggregating distinct rows. Get the value from the distinct 
-        table pointer
-      */
-      Aggregator_distinct *daggr= (Aggregator_distinct *)aggr;
-      val= daggr->table->field[0]->val_real ();
-      arg_is_null= daggr->table->field[0]->is_null();
-    }
-    else
-    {
-      /* non-distinct aggregation */
-      val= args[0]->val_real();
-      arg_is_null= args[0]->null_value;
-    }
-    sum+= val;
-    if (!arg_is_null)
+    sum+= aggr->arg_val_real();
+    if (!aggr->arg_is_null())
       null_value= 0;
   }
   DBUG_RETURN(0);
@@ -1471,6 +1438,45 @@ Aggregator_distinct::~Aggregator_distinc
 }
 
 
+my_decimal *Aggregator_simple::arg_val_decimal(my_decimal *value)
+{
+  return item_sum->args[0]->val_decimal(value);
+}
+
+
+double Aggregator_simple::arg_val_real()
+{
+  return item_sum->args[0]->val_real();
+}
+
+
+bool Aggregator_simple::arg_is_null()
+{
+  return item_sum->args[0]->null_value;
+}
+
+
+my_decimal *Aggregator_distinct::arg_val_decimal(my_decimal * value)
+{
+  return use_distinct_values ? table->field[0]->val_decimal(value) :
+    item_sum->args[0]->val_decimal(value);
+}
+
+
+double Aggregator_distinct::arg_val_real()
+{
+  return use_distinct_values ? table->field[0]->val_real() :
+    item_sum->args[0]->val_real();
+}
+
+
+bool Aggregator_distinct::arg_is_null()
+{
+  return use_distinct_values ? table->field[0]->is_null() :
+    item_sum->args[0]->null_value;
+}
+
+
 Item *Item_sum_count::copy_or_same(THD* thd)
 {
   return new (thd->mem_root) Item_sum_count(thd, this);
@@ -1574,11 +1580,10 @@ void Item_sum_avg::clear()
 
 bool Item_sum_avg::add()
 {
-  if (Item_sum_sum::add())
-    return TRUE;
-  if (!args[0]->null_value)
+  const bool rc= Item_sum_sum::add();
+  if (!aggr->arg_is_null())
     count++;
-  return FALSE;
+  return rc;
 }
 
 double Item_sum_avg::val_real()

=== modified file 'sql/item_sum.h'
--- a/sql/item_sum.h	2010-08-30 07:36:04 +0000
+++ b/sql/item_sum.h	2010-12-02 13:38:12 +0000
@@ -101,6 +101,15 @@ public:
   */
   virtual void endup() = 0;
 
+  /** Decimal value of being-aggregated argument */
+  virtual my_decimal *arg_val_decimal(my_decimal * value) = 0;
+  /** Floating point value of being-aggregated argument */
+  virtual double arg_val_real() = 0;
+  /**
+     NULLness of being-aggregated argument; can be called only after
+     arg_val_decimal() or arg_val_real().
+  */
+  virtual bool arg_is_null() = 0;
 };
 
 
@@ -304,6 +313,7 @@ class st_select_lex;
 class Item_sum :public Item_result_field
 {
   friend class Aggregator_distinct;
+  friend class Aggregator_simple;
 
 protected:
   /**
@@ -600,6 +610,9 @@ public:
   void clear(); 
   bool add();
   void endup();
+  my_decimal *arg_val_decimal(my_decimal * value);
+  double arg_val_real();
+  bool arg_is_null();
 
   bool unique_walk_function(void *element);
   static int composite_key_cmp(void* arg, uchar* key1, uchar* key2);
@@ -623,6 +636,9 @@ public:
   void clear() { item_sum->clear(); }
   bool add() { return item_sum->add(); }
   void endup() {};
+  my_decimal *arg_val_decimal(my_decimal * value);
+  double arg_val_real();
+  bool arg_is_null();
 };
 
 


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bzr commit into mysql-5.5-bugteam branch (guilhem:3125) Bug#57932Guilhem Bichot2 Dec
Re: bzr commit into mysql-5.5-bugteam branch (guilhem:3125) Bug#57932Roy Lyseng7 Dec