BUG#887026: Wrong result with ICP, outer join, subquery in maria-5.3-icp

- Do not push index condition if we're using a triggered ref access.

mysql-test/r/myisam_icp.result

@@ -727,4 +727,34 @@ SELECT a, MIN(c) FROM t1 WHERE b = 'x' AND c > 'x' GROUP BY a;
 a	MIN(c)
 5	y
 DROP TABLE t1;
+#
+# BUG#887026: Wrong result with ICP, outer join, subquery in maria-5.3-icp
+#
+CREATE TABLE t1 (c varchar(1));
+INSERT INTO t1 VALUES ('c'), ('c');
+CREATE TABLE t2 (c varchar(1), b int);
+INSERT INTO t2 VALUES ('d', NULL),('d', NULL);
+CREATE TABLE t3 (c varchar(1));
+INSERT INTO t3 VALUES ('c');
+INSERT INTO t3 VALUES ('c');
+CREATE TABLE t4 ( b int, c varchar(1), KEY (b));
+INSERT INTO t4 VALUES (7,'c');
+INSERT INTO t4 VALUES (7,'c');
+# Must be t1,t2,t3,t4, with t4 having Full-scan-on-NULL but not Using index condition
+explain 
+SELECT * FROM t1 LEFT JOIN t2 ON t1.c=t2.b
+WHERE 
+t2.b NOT IN (SELECT t4.b FROM t3 STRAIGHT_JOIN t4 WHERE t4.b <= 2 AND t4.c = t3.c);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	2	Using where
+2	DEPENDENT SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	2	
+2	DEPENDENT SUBQUERY	t4	ref_or_null	b	b	5	func	2	Using where; Full scan on NULL key
+SELECT * FROM t1 LEFT JOIN t2 ON t1.c=t2.b
+WHERE 
+t2.b NOT IN (SELECT t4.b FROM t3 STRAIGHT_JOIN t4 WHERE t4.b <= 2 AND t4.c = t3.c);
+c	c	b
+c	NULL	NULL
+c	NULL	NULL
+DROP TABLE t1,t2,t3,t4;
 set optimizer_switch=@myisam_icp_tmp;

mysql-test/t/myisam_icp.test

@@ -227,4 +227,34 @@ SELECT a, MIN(c) FROM t1 WHERE b = 'x' AND c > 'x' GROUP BY a;
 
 DROP TABLE t1;
 
+--echo #
+--echo # BUG#887026: Wrong result with ICP, outer join, subquery in maria-5.3-icp
+--echo #
+
+CREATE TABLE t1 (c varchar(1));
+INSERT INTO t1 VALUES ('c'), ('c');
+
+CREATE TABLE t2 (c varchar(1), b int);
+INSERT INTO t2 VALUES ('d', NULL),('d', NULL);
+
+CREATE TABLE t3 (c varchar(1));
+INSERT INTO t3 VALUES ('c');
+INSERT INTO t3 VALUES ('c');
+
+CREATE TABLE t4 ( b int, c varchar(1), KEY (b));
+INSERT INTO t4 VALUES (7,'c');
+INSERT INTO t4 VALUES (7,'c');
+
+--echo # Must be t1,t2,t3,t4, with t4 having Full-scan-on-NULL but not Using index condition
+explain 
+SELECT * FROM t1 LEFT JOIN t2 ON t1.c=t2.b
+WHERE 
+  t2.b NOT IN (SELECT t4.b FROM t3 STRAIGHT_JOIN t4 WHERE t4.b <= 2 AND t4.c = t3.c);
+ 
+SELECT * FROM t1 LEFT JOIN t2 ON t1.c=t2.b
+WHERE 
+  t2.b NOT IN (SELECT t4.b FROM t3 STRAIGHT_JOIN t4 WHERE t4.b <= 2 AND t4.c = t3.c);
+
+DROP TABLE t1,t2,t3,t4;
+
 set optimizer_switch=@myisam_icp_tmp;

sql/sql_select.cc

@@ -9101,11 +9101,9 @@ uint check_join_cache_usage(JOIN_TAB *tab,
   case JT_EQ_REF:
     if (cache_level <=2 || (no_hashed_cache && no_bka_cache))
       goto no_join_cache;
-    for (uint i= 0; i < tab->ref.key_parts; i++)
-    {
-      if (tab->ref.cond_guards[i])
-        goto no_join_cache;
-    }
+    if (tab->ref.is_access_triggered())
+      goto no_join_cache;
+      
     if (!tab->is_ref_for_hash_join())
     {
       flags= HA_MRR_NO_NULL_ENDPOINTS | HA_MRR_SINGLE_POINT;
@@ -9396,9 +9394,9 @@ make_join_readinfo(JOIN *join, ulonglong options, uint no_jbuf_after)
         table->key_read=1;
         table->file->extra(HA_EXTRA_KEYREAD);
       }
-      else if (!jcl || jcl > 4) 
+      else if ((!jcl || jcl > 4) && !tab->ref.is_access_triggered())
         push_index_cond(tab, tab->ref.key);
-        break;
+      break;
     case JT_EQ_REF:
       tab->read_record.unlock_row= join_read_key_unlock_row;
       /* fall through */
@@ -9408,7 +9406,7 @@ make_join_readinfo(JOIN *join, ulonglong options, uint no_jbuf_after)
 	table->key_read=1;
 	table->file->extra(HA_EXTRA_KEYREAD);
       }
-      else if (!jcl || jcl > 4) 
+      else if ((!jcl || jcl > 4) && !tab->ref.is_access_triggered())
         push_index_cond(tab, tab->ref.key);
       break;
     case JT_REF_OR_NULL:
@@ -9423,7 +9421,7 @@ make_join_readinfo(JOIN *join, ulonglong options, uint no_jbuf_after)
       if (table->covering_keys.is_set(tab->ref.key) &&
 	  !table->no_keyread)
         table->enable_keyread();
-      else if (!jcl || jcl > 4)
+      else if ((!jcl || jcl > 4) && !tab->ref.is_access_triggered())
         push_index_cond(tab, tab->ref.key);
       break;
     case JT_ALL:
@@ -9780,6 +9778,22 @@ bool TABLE_REF::tmp_table_index_lookup_init(THD *thd,
 }
 
 
+/*
+  Check if ref access uses "Full scan on NULL key" (i.e. it actually alternates
+  between ref access and full table scan)
+*/
+
+bool TABLE_REF::is_access_triggered()
+{
+  for (uint i = 0; i < key_parts; i++)
+  {
+    if (cond_guards[i])
+      return TRUE;
+  }
+  return FALSE;
+}
+
+
 /**
   Partially cleanup JOIN after it has executed: close index or rnd read
   (table cursors), free quick selects.
@@ -16656,13 +16670,8 @@ bool test_if_ref(Item *root_cond, Item_field *left_item,Item *right_item)
       between ref access and full table scan), then no equality can be
       guaranteed to be true.
     */
-    for (uint i = 0; i < join_tab->ref.key_parts; i++)
-    {
-      if (join_tab->ref.cond_guards[i])
-      {
-        return FALSE;
-      }
-    }
+    if (join_tab->ref.is_access_triggered())
+      return FALSE;
 
     Item *ref_item=part_of_refkey(field->table,field);
     if (ref_item && (ref_item->eq(right_item,1) || 

sql/sql_select.h

@@ -136,6 +136,7 @@ typedef struct st_table_ref
 
   bool tmp_table_index_lookup_init(THD *thd, KEY *tmp_key, Item_iterator &it,
                                    bool value, uint skip= 0);
+  bool is_access_triggered();
 } TABLE_REF;