Bug#48459: valgrind errors with query using 'Range checked

for each record'

There was an error in an internal structure in the range
optimizer (SEL_ARG). Bad design causes parts of a data
structure not to be initialized when it is in a certain
state. All client code must check that this state is not
present before trying to access the structure's data. Fixed
by

- Checking the state before trying to access data (in
several places, most of which not covered by test case.)

- Copying the keypart id when cloning SEL_ARGs


mysql-test/r/range.result:
  Bug#48459: Test result.
mysql-test/t/range.test:
  Bug#48459: Test case.
sql/opt_range.cc:
  Bug#48459: Fix + doxygenated count_key_part_usage comment.

mysql-test/r/range.result

@@ -1604,6 +1604,39 @@ str_to_date('', '%Y-%m-%d')
 0000-00-00
 DROP TABLE t1, t2;
 #
+# Bug#48459: valgrind errors with query using 'Range checked for each 
+# record'
+#
+CREATE TABLE t1 (
+a INT,
+b CHAR(2),
+c INT,
+d INT,
+KEY ( c ),
+KEY ( d, a, b ( 2 ) ),
+KEY ( b ( 1 ) )
+);
+INSERT INTO t1 VALUES ( NULL, 'a', 1, 2 ), ( NULL, 'a', 1, 2 ),
+( 1,    'a', 1, 2 ), ( 1,    'a', 1, 2 );
+CREATE TABLE t2 (
+a INT,
+c INT,
+e INT,
+KEY ( e )
+);
+INSERT INTO t2 VALUES ( 1, 1, NULL ), ( 1, 1, NULL );
+# Should not give Valgrind warnings
+SELECT 1
+FROM t1, t2
+WHERE t1.d <> '1' AND t1.b > '1'
+AND t1.a = t2.a AND t1.c = t2.c;
+1
+1
+1
+1
+1
+DROP TABLE t1, t2;
+#
 # Bug #48665: sql-bench's insert test fails due to wrong result
 #
 CREATE TABLE t1 (a INT, b INT, PRIMARY KEY (a));

mysql-test/t/range.test

@@ -1260,6 +1260,39 @@ SELECT str_to_date('', '%Y-%m-%d');
 
 DROP TABLE t1, t2;
 
+--echo #
+--echo # Bug#48459: valgrind errors with query using 'Range checked for each 
+--echo # record'
+--echo #
+CREATE TABLE t1 (
+  a INT,
+  b CHAR(2),
+  c INT,
+  d INT,
+  KEY ( c ),
+  KEY ( d, a, b ( 2 ) ),
+  KEY ( b ( 1 ) )
+);
+
+INSERT INTO t1 VALUES ( NULL, 'a', 1, 2 ), ( NULL, 'a', 1, 2 ),
+                      ( 1,    'a', 1, 2 ), ( 1,    'a', 1, 2 );
+
+CREATE TABLE t2 (
+  a INT,
+  c INT,
+  e INT,
+  KEY ( e )
+);
+
+INSERT INTO t2 VALUES ( 1, 1, NULL ), ( 1, 1, NULL );
+
+--echo # Should not give Valgrind warnings
+SELECT 1
+FROM t1, t2
+WHERE t1.d <> '1' AND t1.b > '1'
+AND t1.a = t2.a AND t1.c = t2.c;
+
+DROP TABLE t1, t2;
 
 --echo #
 --echo # Bug #48665: sql-bench's insert test fails due to wrong result
@@ -1280,5 +1313,4 @@ SELECT * FROM t1 FORCE INDEX (PRIMARY)
 
 DROP TABLE t1;
 
-
 --echo End of 5.1 tests

sql/opt_range.cc

@@ -446,9 +446,9 @@ class SEL_ARG :public Sql_alloc
                                   range_key, *range_key_flag);
     *range_key_flag|= key_tree->min_flag;
     if (key_tree->next_key_part &&
+	key_tree->next_key_part->type == SEL_ARG::KEY_RANGE &&
 	key_tree->next_key_part->part == key_tree->part+1 &&
-	!(*range_key_flag & (NO_MIN_RANGE | NEAR_MIN)) &&
-	key_tree->next_key_part->type == SEL_ARG::KEY_RANGE)
+	!(*range_key_flag & (NO_MIN_RANGE | NEAR_MIN)))
       res+= key_tree->next_key_part->store_min_key(key, range_key,
                                                    range_key_flag);
     return res;
@@ -462,9 +462,9 @@ class SEL_ARG :public Sql_alloc
                                  range_key, *range_key_flag);
     (*range_key_flag)|= key_tree->max_flag;
     if (key_tree->next_key_part &&
+	key_tree->next_key_part->type == SEL_ARG::KEY_RANGE &&
 	key_tree->next_key_part->part == key_tree->part+1 &&
-	!(*range_key_flag & (NO_MAX_RANGE | NEAR_MAX)) &&
-	key_tree->next_key_part->type == SEL_ARG::KEY_RANGE)
+	!(*range_key_flag & (NO_MAX_RANGE | NEAR_MAX)))
       res+= key_tree->next_key_part->store_max_key(key, range_key,
                                                    range_key_flag);
     return res;
@@ -1700,6 +1700,7 @@ SEL_ARG *SEL_ARG::clone(RANGE_OPT_PARAM *param, SEL_ARG *new_parent,
     tmp->prev= *next_arg;			// Link into next/prev chain
     (*next_arg)->next=tmp;
     (*next_arg)= tmp;
+    tmp->part= this->part;
   }
   else
   {
@@ -7290,15 +7291,13 @@ int test_rb_tree(SEL_ARG *element,SEL_ARG *parent)
 }
 
 
-/*
-  Count how many times SEL_ARG graph "root" refers to its part "key"
+/**
+  Count how many times SEL_ARG graph "root" refers to its part "key" via
+  transitive closure.
   
-  SYNOPSIS
-    count_key_part_usage()
-      root  An RB-Root node in a SEL_ARG graph.
-      key   Another RB-Root node in that SEL_ARG graph.
+  @param root  An RB-Root node in a SEL_ARG graph.
+  @param key   Another RB-Root node in that SEL_ARG graph.
 
-  DESCRIPTION
   The passed "root" node may refer to "key" node via root->next_key_part,
   root->next->n
 
@@ -7330,7 +7329,7 @@ int test_rb_tree(SEL_ARG *element,SEL_ARG *parent)
           ...     +---+       $    |
                   |   |------------+
                   +---+       $
-  RETURN 
+  @return 
   Number of links to "key" from nodes reachable from "root".
 */
 
@@ -7586,8 +7585,8 @@ check_quick_keys(PARAM *param, uint idx, SEL_ARG *key_tree,
     param->first_null_comp= key_tree->part+1;
 
   if (key_tree->next_key_part &&
-      key_tree->next_key_part->part == key_tree->part+1 &&
-      key_tree->next_key_part->type == SEL_ARG::KEY_RANGE)
+      key_tree->next_key_part->type == SEL_ARG::KEY_RANGE &&
+      key_tree->next_key_part->part == key_tree->part+1)
   {						// const key as prefix
     if (min_key_length == max_key_length &&
 	!memcmp(min_key, max_key, (uint) (tmp_max_key - max_key)) &&
@@ -7868,8 +7867,8 @@ get_quick_keys(PARAM *param,QUICK_RANGE_SELECT *quick,KEY_PART *key,
                                  &tmp_max_key,max_key_flag);
 
   if (key_tree->next_key_part &&
-      key_tree->next_key_part->part == key_tree->part+1 &&
-      key_tree->next_key_part->type == SEL_ARG::KEY_RANGE)
+      key_tree->next_key_part->type == SEL_ARG::KEY_RANGE &&
+      key_tree->next_key_part->part == key_tree->part+1)
   {						  // const key as prefix
     if ((tmp_min_key - min_key) == (tmp_max_key - max_key) &&
          memcmp(min_key, max_key, (uint)(tmp_max_key - max_key))==0 &&