Better bugfix for "HAVING when refering to RAND()" (Bug #8216)

Ensure that references in HAVING, ORDER BY or GROUP BY are calculated after fields in SELECT.
This will ensure that any reference to these has a valid value.
Generalized the code for split_sum_func()

1 files changed, 6 insertions, 46 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index 2b9a612da18..a827f316ec1 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -1969,10 +1969,10 @@ bool Item_cond::walk(Item_processor processor, byte *arg)
   Move SUM items out from item tree and replace with reference
 
   SYNOPSIS
-  split_sum_func()
-  thd			Thread handler
-  ref_pointer_array	Pointer to array of reference fields
-  fields		All fields in select
+    split_sum_func()
+    thd			Thread handler
+    ref_pointer_array	Pointer to array of reference fields
+    fields		All fields in select
 
   NOTES
    This function is run on all expression (SELECT list, WHERE, HAVING etc)
@@ -1982,16 +1982,6 @@ bool Item_cond::walk(Item_processor processor, byte *arg)
    so that we can easily find and calculate them.
    (Calculation done by update_sum_func() and copy_sum_funcs() in
    sql_select.cc)
-
-   All found SUM items are added FIRST in the fields list and
-   we replace the item with a reference.
-
-   We also replace all functions without side effects (like RAND() or UDF's)
-   that uses columns as arguments.
-   For functions with side effects, we just remember any fields referred
-   by the function to ensure that we get a copy of the field value for the
-   first accepted row. This ensures that we can do things like
-   SELECT a*SUM(b) FROM t1 WHERE a=1
 */
 
 void Item_cond::split_sum_func(THD *thd, Item **ref_pointer_array,
@@ -1999,38 +1989,8 @@ void Item_cond::split_sum_func(THD *thd, Item **ref_pointer_array,
 {
   List_iterator<Item> li(list);
   Item *item;
-  used_tables_cache=0;
-  const_item_cache=0;
-  while ((item=li++))
-  {
-    /* with_sum_func is set for items that contains a SUM expression */
-    if (item->type() != SUM_FUNC_ITEM &&
-        (item->with_sum_func ||
-         (item->used_tables() & PSEUDO_TABLE_BITS)))
-      item->split_sum_func(thd, ref_pointer_array, fields);
-    else if (item->type() == SUM_FUNC_ITEM ||
-             (item->used_tables() && item->type() != REF_ITEM))
-    {
-      /*
-        Replace item with a reference so that we can easily calculate
-        it (in case of sum functions) or copy it (in case of fields)
-
-        The test above is to ensure we don't do a reference for things
-        that are constants or are not yet calculated as in:
-        SELECT RAND() as r1, SUM(a) as r2 FROM t1 HAVING r1 > 1 AND r2 > 0
-      */
-      Item **ref= li.ref();
-      uint el= fields.elements;
-      ref_pointer_array[el]= item;
-      Item *new_item= new Item_ref(ref_pointer_array + el, 0, item->name);
-      fields.push_front(item);
-      ref_pointer_array[el]= item;
-      thd->change_item_tree(ref, new_item);
-    }
-    item->update_used_tables();
-    used_tables_cache|=item->used_tables();
-    const_item_cache&=item->const_item();
-  }
+  while ((item= li++))
+    item->split_sum_func2(thd, ref_pointer_array, fields, li.ref());
 }