Fixed bug in MAX() optimization when used with JOIN and ON expressions

(Patch from 4.0.5)


mysql-test/r/group_by.result:
  Updated results
mysql-test/t/group_by.test:
  Test for bug
sql/item_cmpfunc.cc:
  Fixed bug in MAX() optimization when used with JOIN and ON expressions
sql/item_cmpfunc.h:
  Fixed bug in MAX() optimization when used with JOIN and ON expressions
sql/opt_sum.cc:
  Fixed bug in MAX() optimization when used with JOIN and ON expressions

mysql-test/r/group_by.result

@@ -84,3 +84,9 @@ xID	xID1	Level
 2	2	**
 3	134	***
 4	185	****
+pid	c1id	c2id	value	id	active	id	active
+1	1	NULL	1	1	Yes	NULL	NULL
+1	NULL	3	3	NULL	NULL	3	Yes
+1	4	NULL	4	4	Yes	NULL	NULL
+max(value)
+4

mysql-test/t/group_by.test

@@ -2,7 +2,7 @@
 # Test of group (Failed for Lars Hoss <lh@pbm.de>)
 #
 
-drop table if exists t1,t2;
+drop table if exists t1,t2,t3;
 CREATE TABLE t1 (
   spID int(10) unsigned,
   userID int(10) unsigned,
@@ -270,3 +270,42 @@ insert into t1 values (1,244,NULL),(2,243,NULL),(134,223,NULL),(185,186,NULL);
 select S.ID as xID, S.ID1 as xID1 from t1 as S left join t1 as yS  on S.ID1 between yS.ID1 and yS.ID2;
 select S.ID as xID, S.ID1 as xID1, repeat('*',count(distinct yS.ID)) as Level from t1 as S left join t1 as yS  on S.ID1 between yS.ID1 and yS.ID2 group by xID order by xID1;
 drop table t1;
+
+#
+# Problem with MAX and LEFT JOIN
+#
+
+CREATE TABLE t1 (
+  pid int(11) unsigned NOT NULL default '0',
+  c1id int(11) unsigned default NULL,
+  c2id int(11) unsigned default NULL,
+  value int(11) unsigned NOT NULL default '0',
+  UNIQUE KEY pid2 (pid,c1id,c2id),
+  UNIQUE KEY pid (pid,value)
+) TYPE=MyISAM;
+
+INSERT INTO t1 VALUES (1, 1, NULL, 1),(1, 2, NULL, 2),(1, NULL, 3, 3),(1, 4, NULL, 4),(1, 5, NULL, 5);
+
+CREATE TABLE t2 (
+  id int(11) unsigned NOT NULL default '0',
+  active enum('Yes','No') NOT NULL default 'Yes',
+  PRIMARY KEY  (id)
+) TYPE=MyISAM;
+
+INSERT INTO t2 VALUES (1, 'Yes'),(2, 'No'),(4, 'Yes'),(5, 'No');
+
+CREATE TABLE t3 (
+  id int(11) unsigned NOT NULL default '0',
+  active enum('Yes','No') NOT NULL default 'Yes',
+  PRIMARY KEY  (id)
+);
+INSERT INTO t3 VALUES (3, 'Yes');
+
+select * from t1 AS m LEFT JOIN t2 AS c1 ON m.c1id = 
+c1.id AND c1.active = 'Yes' LEFT JOIN t3 AS c2 ON m.c2id = c2.id AND 
+c2.active = 'Yes' WHERE m.pid=1  AND (c1.id IS NOT NULL OR c2.id IS NOT NULL);
+select max(value) from t1 AS m LEFT JOIN t2 AS c1 ON 
+m.c1id = c1.id AND c1.active = 'Yes' LEFT JOIN t3 AS c2 ON m.c2id = 
+c2.id AND c2.active = 'Yes' WHERE m.pid=1  AND (c1.id IS NOT NULL OR c2.id IS 
+NOT NULL);
+drop table t1,t2,t3;

sql/item_cmpfunc.cc

@@ -1207,6 +1207,45 @@ longlong Item_cond_or::val_int()
   return 0;
 }
 
+/*
+  Create an AND expression from two expressions
+
+  SYNOPSIS
+   and_expressions()
+   a		expression or NULL
+   b    	expression.
+   org_item	Don't modify a if a == *org_item
+		If a == NULL, org_item is set to point at b,
+		to ensure that future calls will not modify b.
+
+  NOTES
+    This will not modify item pointed to by org_item or b
+    The idea is that one can call this in a loop and create and
+    'and' over all items without modifying any of the original items.
+
+  RETURN
+    NULL	Error
+    Item
+*/
+
+Item *and_expressions(Item *a, Item *b, Item **org_item)
+{
+  if (!a)
+    return (*org_item= (Item*) b);
+  if (a == *org_item)
+  {
+    Item_cond *res;
+    if ((res= new Item_cond_and(a, (Item*) b)))
+      res->used_tables_cache= a->used_tables() | b->used_tables();
+    return res;
+  }
+  if (((Item_cond_and*) a)->add((Item*) b))
+    return 0;
+  ((Item_cond_and*) a)->used_tables_cache|= b->used_tables();
+  return a;
+}
+
+
 longlong Item_func_isnull::val_int()
 {
   /*

sql/item_cmpfunc.h

@@ -573,3 +573,5 @@ inline Item *and_conds(Item *a,Item *b)
     cond->update_used_tables();
   return cond;
 }
+
+Item *and_expressions(Item *a, Item *b, Item **org_item);

sql/opt_sum.cc

@@ -37,6 +37,19 @@ int opt_sum_query(TABLE_LIST *tables, List<Item> &all_fields,COND *conds)
   bool recalc_const_item=0;
   table_map removed_tables=0;
   Item *item;
+  COND *org_conds= conds;
+  
+  /* Add all ON conditions to WHERE condition */
+  for (TABLE_LIST *tl=tables; tl ; tl= tl->next)
+  {
+    if (tl->on_expr)
+      conds= and_expressions(conds, tl->on_expr, &org_conds);
+  }
+
+  /*
+    Iterate through item is select part and replace COUNT(), MIN() and MAX()
+    with constants (if possible)
+  */
 
   while ((item= it++))
   {