bzr commit into mysql-next-mr-bugfixing branch (tor.didriksen:3155) Bug#52123

[Tor Didriksen]

#At file:///export/home/didrik/mysqldev-next-mr/next-mr-bf-bug52123/ based on revid:marc.alff@stripped

 3155 Tor Didriksen	2010-04-09
      Bug#52123 Assertion failed: aggregator == aggr->Aggrtype(), file .\item_sum.cc, line 587
      
      For certain queries we actually change the aggregator type:
      e.g. first initialize and copy aggregator type in 
      Item_sum::Item_sum(THD *thd, Item_sum *item)
      then change the type in prepare_sum_aggregators()
     @ mysql-test/r/func_group.result
        Add test case.
     @ mysql-test/t/func_group.test
        Add test case.
     @ sql/item_sum.cc
        Delete the old aggregator if the type changes.
     @ sql/item_sum.h
        set_aggregator() may be called multiple times.

    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	2009-12-22 16:23:13 +0000
+++ b/mysql-test/r/func_group.result	2010-04-09 11:20:40 +0000
@@ -1714,3 +1714,13 @@ NULL	NULL	NULL	NULL	NULL
 drop table t1;
 #
 End of 5.1 tests
+#
+# Bug#52123 Assertion failed: aggregator == aggr->Aggrtype(),
+#           file .\item_sum.cc, line 587
+#
+CREATE TABLE t1(a int, KEY(a));
+INSERT INTO t1 VALUES (1), (2);
+SELECT 1 FROM t1 ORDER BY AVG(DISTINCT a);
+1
+1
+DROP TABLE t1;

=== modified file 'mysql-test/t/func_group.test'
--- a/mysql-test/t/func_group.test	2009-11-24 15:26:13 +0000
+++ b/mysql-test/t/func_group.test	2010-04-09 11:20:40 +0000
@@ -1085,3 +1085,13 @@ drop table t1;
 --echo #
 --echo End of 5.1 tests
 
+--echo #
+--echo # Bug#52123 Assertion failed: aggregator == aggr->Aggrtype(),
+--echo #           file .\item_sum.cc, line 587
+--echo #
+
+CREATE TABLE t1(a int, KEY(a));
+INSERT INTO t1 VALUES (1), (2);
+SELECT 1 FROM t1 ORDER BY AVG(DISTINCT a);
+DROP TABLE t1;
+

=== modified file 'sql/item_sum.cc'
--- a/sql/item_sum.cc	2010-03-31 14:05:33 +0000
+++ b/sql/item_sum.cc	2010-04-09 11:20:40 +0000
@@ -576,24 +576,27 @@ Item *Item_sum::set_arg(uint i, THD *thd
 
 int Item_sum::set_aggregator(Aggregator::Aggregator_type aggregator)
 {
-  if (aggr)
+  /*
+    Dependent subselects may be executed multiple times, making
+    set_aggregator to be called multiple times. The aggregator type
+    will be the same, but it needs to be reset so that it is
+    reevaluated with the new dependent data.
+    This function may also be called multiple times during query optimization.
+    In this case, the type may change, so we delete the old aggregator,
+    and create a new one.
+  */
+  if (aggr && aggregator == aggr->Aggrtype())
   {
-    /* 
-      Dependent subselects may be executed multiple times, making
-      set_aggregator to be called multiple times. The aggregator type
-      will be the same, but it needs to be reset so that it is
-      reevaluated with the new dependent data.
-    */
-    DBUG_ASSERT(aggregator == aggr->Aggrtype());
     aggr->clear();
     return FALSE;
   }
+
+  delete aggr;
   switch (aggregator)
   {
   case Aggregator::DISTINCT_AGGREGATOR:
     aggr= new Aggregator_distinct(this);
     break;
-
   case Aggregator::SIMPLE_AGGREGATOR:
     aggr= new Aggregator_simple(this);
     break;

=== modified file 'sql/item_sum.h'
--- a/sql/item_sum.h	2010-03-31 14:05:33 +0000
+++ b/sql/item_sum.h	2010-04-09 11:20:40 +0000
@@ -441,10 +441,9 @@ public:  
   */
   virtual void no_rows_in_result()
   {
-    if (!aggr)
-      set_aggregator(with_distinct ?
-                     Aggregator::DISTINCT_AGGREGATOR :
-                     Aggregator::SIMPLE_AGGREGATOR);
+    set_aggregator(with_distinct ?
+                   Aggregator::DISTINCT_AGGREGATOR :
+                   Aggregator::SIMPLE_AGGREGATOR);
     reset();
   }
   virtual void make_unique() { force_copy_fields= TRUE; }
@@ -495,11 +494,10 @@ public:  
     quick_group= with_distinct ? 0 : 1;
   }
 
-  /**
+  /*
     Set the type of aggregation : DISTINCT or not.
 
-    Called when the final determination is done about the aggregation
-    type and the object is about to be used.
+    May be called multiple times.
   */
 
   int set_aggregator(Aggregator::Aggregator_type aggregator);


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