Fixed LP bug #823301.

A bug in the code of the function key_or could lead to a situation
when performing of an OR operation for one index changes the result
the operation for another index. This bug is fixed with this patch.

Also corrected the specification and the code of the function 
or_sel_tree_with_checks.

4 files changed, 119 insertions, 12 deletions

diff --git a/mysql-test/r/range_vs_index_merge.result b/mysql-test/r/range_vs_index_merge.result
index 08ede868ed6..f1838bc9aae 100644
--- a/mysql-test/r/range_vs_index_merge.result
+++ b/mysql-test/r/range_vs_index_merge.result
@@ -1377,4 +1377,41 @@ SELECT * FROM t1,t2,t3
 WHERE (t2.f3 = 1 OR t3.f1=t2.f1) AND t3.f1 <> t2.f2 AND t3.f2 = t2.f4;
 f1	f1	f2	f3	f4	f1	f2
 DROP TABLE t1,t2,t3;
+CREATE TABLE t1 (
+a int, b int, c int, d int,
+PRIMARY KEY(b), INDEX idx1(d), INDEX idx2(d,b,c)
+);
+INSERT INTO t1 VALUES 
+(0,58,7,7),(0,63,2,0),(0,64,186,8),(0,65,1,-2), (0,71,190,-3),
+(0,72,321,-7),(0,73,0,3),(0,74,5,25),(0,75,5,3);
+SET SESSION optimizer_switch='index_merge_sort_union=off';
+EXPLAIN
+SELECT * FROM t1 
+WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	PRIMARY,idx1,idx2	NULL	NULL	NULL	9	Using where
+SELECT * FROM t1 
+WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+a	b	c	d
+0	58	7	7
+0	64	186	8
+0	73	0	3
+0	74	5	25
+0	75	5	3
+SET SESSION optimizer_switch='index_merge_sort_union=on';
+EXPLAIN
+SELECT * FROM t1 
+WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	PRIMARY,idx1,idx2	NULL	NULL	NULL	9	Using where
+SELECT * FROM t1 
+WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+a	b	c	d
+0	58	7	7
+0	64	186	8
+0	73	0	3
+0	74	5	25
+0	75	5	3
+SET SESSION optimizer_switch=DEFAULT;
+DROP TABLE t1;
 set session optimizer_switch='index_merge_sort_intersection=default';
diff --git a/mysql-test/r/range_vs_index_merge_innodb.result b/mysql-test/r/range_vs_index_merge_innodb.result
index 54151a7c2db..82297158c8c 100644
--- a/mysql-test/r/range_vs_index_merge_innodb.result
+++ b/mysql-test/r/range_vs_index_merge_innodb.result
@@ -1378,5 +1378,42 @@ SELECT * FROM t1,t2,t3
 WHERE (t2.f3 = 1 OR t3.f1=t2.f1) AND t3.f1 <> t2.f2 AND t3.f2 = t2.f4;
 f1	f1	f2	f3	f4	f1	f2
 DROP TABLE t1,t2,t3;
+CREATE TABLE t1 (
+a int, b int, c int, d int,
+PRIMARY KEY(b), INDEX idx1(d), INDEX idx2(d,b,c)
+);
+INSERT INTO t1 VALUES 
+(0,58,7,7),(0,63,2,0),(0,64,186,8),(0,65,1,-2), (0,71,190,-3),
+(0,72,321,-7),(0,73,0,3),(0,74,5,25),(0,75,5,3);
+SET SESSION optimizer_switch='index_merge_sort_union=off';
+EXPLAIN
+SELECT * FROM t1 
+WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	PRIMARY,idx1,idx2	NULL	NULL	NULL	9	Using where
+SELECT * FROM t1 
+WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+a	b	c	d
+0	58	7	7
+0	64	186	8
+0	73	0	3
+0	74	5	25
+0	75	5	3
+SET SESSION optimizer_switch='index_merge_sort_union=on';
+EXPLAIN
+SELECT * FROM t1 
+WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	PRIMARY,idx1,idx2	NULL	NULL	NULL	9	Using where
+SELECT * FROM t1 
+WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+a	b	c	d
+0	58	7	7
+0	64	186	8
+0	73	0	3
+0	74	5	25
+0	75	5	3
+SET SESSION optimizer_switch=DEFAULT;
+DROP TABLE t1;
 set session optimizer_switch='index_merge_sort_intersection=default';
 SET SESSION STORAGE_ENGINE=DEFAULT;
diff --git a/mysql-test/t/range_vs_index_merge.test b/mysql-test/t/range_vs_index_merge.test
index 1f7065dcb0a..2ffa2d8eb49 100755
--- a/mysql-test/t/range_vs_index_merge.test
+++ b/mysql-test/t/range_vs_index_merge.test
@@ -1029,5 +1029,34 @@ SELECT * FROM t1,t2,t3
 
 DROP TABLE t1,t2,t3;
 
+#
+# LP bug #823301: index merge union with prossible index scan  
+#              
+#
+
+CREATE TABLE t1 (
+  a int, b int, c int, d int,
+  PRIMARY KEY(b), INDEX idx1(d), INDEX idx2(d,b,c)
+);
+INSERT INTO t1 VALUES 
+ (0,58,7,7),(0,63,2,0),(0,64,186,8),(0,65,1,-2), (0,71,190,-3),
+ (0,72,321,-7),(0,73,0,3),(0,74,5,25),(0,75,5,3);
+
+SET SESSION optimizer_switch='index_merge_sort_union=off';
+EXPLAIN
+SELECT * FROM t1 
+  WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+SELECT * FROM t1 
+  WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+SET SESSION optimizer_switch='index_merge_sort_union=on';
+EXPLAIN
+SELECT * FROM t1 
+  WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+SELECT * FROM t1 
+  WHERE t1.b>7 AND t1.d>1 AND t1.d<>8  OR t1.d>=7 AND t1.d<8 OR t1.d>7;
+SET SESSION optimizer_switch=DEFAULT;
+
+DROP TABLE t1;
+
 #the following command must be the last one in the file
 set session optimizer_switch='index_merge_sort_intersection=default';
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 3ed975a59bb..815a6f5f316 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -1136,10 +1136,10 @@ int SEL_IMERGE::and_sel_tree(RANGE_OPT_PARAM *param, SEL_TREE *tree,
 
     2. In the second mode, when is_first_check_pass==FALSE :
       2.1. For each rt_j in the imerge that can be ored (see the function
-           sel_trees_can_be_ored), but not must be ored, with rt the function
-           replaces rt_j for a range tree such that for each index for which
-           ranges are defined in both in rt_j and rt  the tree contains the
-           result of oring of these ranges.
+           sel_trees_can_be_ored) with rt the function replaces rt_j for a
+           range tree such that for each index for which ranges are defined
+           in both in rt_j and rt  the tree contains the  result of oring of
+           these ranges.
       2.2. In other cases the function does not produce any imerge.
 
     When is_first_check==TRUE the function returns FALSE in the parameter
@@ -1163,7 +1163,7 @@ int SEL_IMERGE::or_sel_tree_with_checks(RANGE_OPT_PARAM *param,
                                         bool *is_last_check_pass)
 {
   bool was_ored= FALSE;
-  *is_last_check_pass= TRUE;
+  *is_last_check_pass= is_first_check_pass;
   SEL_TREE** or_tree = trees;
   for (uint i= 0; i < n_trees; i++, or_tree++)
   {
@@ -1174,7 +1174,7 @@ int SEL_IMERGE::or_sel_tree_with_checks(RANGE_OPT_PARAM *param,
     {
       bool must_be_ored= sel_trees_must_be_ored(param, *or_tree, tree,
                                                 ored_keys);
-      if (must_be_ored || !is_first_check_pass) 
+      if (must_be_ored || !is_first_check_pass)
       {
         result_keys.clear_all();
         result= *or_tree;
@@ -1210,22 +1210,19 @@ int SEL_IMERGE::or_sel_tree_with_checks(RANGE_OPT_PARAM *param,
     {
       if (result_keys.is_clear_all())
         result->type= SEL_TREE::ALWAYS;
-      *is_last_check_pass= TRUE;
       if ((result->type == SEL_TREE::MAYBE) ||
           (result->type == SEL_TREE::ALWAYS))
         return 1;
       /* SEL_TREE::IMPOSSIBLE is impossible here */
       result->keys_map= result_keys; 
       *or_tree= result;
-      if (is_first_check_pass)
-        return 0;
       was_ored= TRUE;
     }
   }
   if (was_ored)
     return 0;
 
-  if (!*is_last_check_pass && 
+  if (is_first_check_pass && !*is_last_check_pass &&
       !(tree= new SEL_TREE(tree, FALSE, param)))
     return (-1);
   return or_sel_tree(param, tree);
@@ -8382,9 +8379,9 @@ tree_or(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2)
     /* Build the imerge part of the tree for the formula (1) */
     SEL_TREE *rt1= tree1;
     SEL_TREE *rt2= tree2;
-    if (!no_merges1)
+    if (no_merges1)
       rt1= new SEL_TREE(tree1, TRUE, param);
-    if (!no_merges2)
+    if (no_merges2)
       rt2= new SEL_TREE(tree2, TRUE, param);
     if (!rt1 || !rt2 ||
         result->merges.push_back(imerge_from_ranges) ||
@@ -9079,6 +9076,13 @@ key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2)
             key2:               [---]
             tmp:     [---------]
           */
+          if (key2->use_count)
+	  {
+	    SEL_ARG *key2_cpy= new SEL_ARG(*key2);
+            if (key2_cpy)
+              return 0;
+            key2= key2_cpy;
+	  }
           key2->copy_max_to_min(tmp);
           continue;
         }