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.

1 files changed, 28 insertions, 29 deletions

diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 9d8d3bd43d9..94204962345 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -446,9 +446,9 @@ public:
                                   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 @@ public:
                                  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
   {
@@ -7290,27 +7291,25 @@ 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.
-
-  DESCRIPTION
-    The passed "root" node may refer to "key" node via root->next_key_part,
-    root->next->n
-
-    This function counts how many times the node "key" is referred (via
-    SEL_ARG::next_key_part) by 
-     - intervals of RB-tree pointed by "root", 
-     - intervals of RB-trees that are pointed by SEL_ARG::next_key_part from 
-       intervals of RB-tree pointed by "root",
-     - and so on.
+  @param root  An RB-Root node in a SEL_ARG graph.
+  @param key   Another RB-Root node in that SEL_ARG graph.
+
+  The passed "root" node may refer to "key" node via root->next_key_part,
+  root->next->n
+
+  This function counts how many times the node "key" is referred (via
+  SEL_ARG::next_key_part) by 
+  - intervals of RB-tree pointed by "root", 
+  - intervals of RB-trees that are pointed by SEL_ARG::next_key_part from 
+  intervals of RB-tree pointed by "root",
+  - and so on.
     
-    Here is an example (horizontal links represent next_key_part pointers, 
-    vertical links - next/prev prev pointers):  
+  Here is an example (horizontal links represent next_key_part pointers, 
+  vertical links - next/prev prev pointers):  
     
          +----+               $
          |root|-----------------+
@@ -7330,8 +7329,8 @@ int test_rb_tree(SEL_ARG *element,SEL_ARG *parent)
           ...     +---+       $    |
                   |   |------------+
                   +---+       $
-  RETURN 
-    Number of links to "key" from nodes reachable from "root".
+  @return 
+  Number of links to "key" from nodes reachable from "root".
 */
 
 static ulong count_key_part_usage(SEL_ARG *root, SEL_ARG *key)
@@ -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 &&