MDEV-24117: Memory management problem in statistics state for ... IN

Part#1: Revert the patch that caused it:

commit 291be494744abe90f4bdf6b5a35c4c26ee8ddda5
Author: Igor Babaev <igor@askmonty.org>
Date:   Thu Sep 24 22:02:00 2020 -0700

    MDEV-23811: With large number of indexes optimizer chooses an inefficient plan

5 files changed, 11 insertions, 201 deletions

diff --git a/mysql-test/r/range.result b/mysql-test/r/range.result
index 7299982e72d..26ea2c6d323 100644
--- a/mysql-test/r/range.result
+++ b/mysql-test/r/range.result
@@ -1274,7 +1274,7 @@ SELECT * FROM t1 WHERE
 5 <= a AND b = 3 OR
 3 <= a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	a	a	5	NULL	3	Using where; Using index
+1	SIMPLE	t1	range	a	a	5	NULL	4	Using where; Using index
 SELECT * FROM t1 WHERE
 3 <= a AND a <= 5 OR 
 5 <= a AND b = 3 OR
@@ -3054,77 +3054,5 @@ a	b
 set eq_range_index_dive_limit=default;
 drop table t1;
 #
-# MDEV-23811: Both disjunct of WHERE condition contain range conditions
-#             for the same index such that the second range condition
-#             fully covers the first one. Additionally one of the disjuncts
-#             contains a range condition for the other index.
-#
-create table t1 (
-pk int primary key auto_increment, a int, b int,
-index idx1(a), index idx2(b)
-);
-insert into t1(a,b) values
-(5,50), (1,10), (3,30), (7,70), (8,80), (4,40), (2,20), (6,60);
-insert into t1(a,b) select a+10, b+100 from t1;
-insert into t1(a,b) select a+20, b+200 from t1;
-insert into t1(a,b) select a+30, b+300 from t1;
-insert into t1(a,b) select a,b from t1;
-analyze table t1;
-Table	Op	Msg_type	Msg_text
-test.t1	analyze	status	OK
-explain select * from t1 where ((a between 3 and 4) and b < 100) or (a between 2 and 5);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	idx1,idx2	idx1	5	NULL	11	Using index condition; Using where
-select * from t1 where ((a between 3 and 4) and b < 100) or (a between 2 and 5);
-pk	a	b
-7	2	20
-71	2	20
-3	3	30
-67	3	30
-6	4	40
-70	4	40
-1	5	50
-65	5	50
-explain select * from t1 where (a between 2 and 5) or ((a between 3 and 4) and b < 100);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	idx1,idx2	idx1	5	NULL	11	Using index condition; Using where
-select * from t1 where (a between 2 and 5) or ((a between 3 and 4) and b < 100);
-pk	a	b
-7	2	20
-71	2	20
-3	3	30
-67	3	30
-6	4	40
-70	4	40
-1	5	50
-65	5	50
-explain select * from t1 where (a between 3 and 4) or ((a between 2 and 5) and b < 100);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	idx1,idx2	idx1	5	NULL	11	Using index condition; Using where
-select * from t1 where (a between 3 and 4) or ((a between 2 and 5) and b < 100);
-pk	a	b
-7	2	20
-71	2	20
-3	3	30
-67	3	30
-6	4	40
-70	4	40
-1	5	50
-65	5	50
-explain select * from t1 where ((a between 2 and 5) and b < 100) or (a between 3 and 4);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	idx1,idx2	idx1	5	NULL	11	Using index condition; Using where
-select * from t1 where ((a between 2 and 5) and b < 100) or (a between 3 and 4);
-pk	a	b
-7	2	20
-71	2	20
-3	3	30
-67	3	30
-6	4	40
-70	4	40
-1	5	50
-65	5	50
-drop table t1;
-#
 # End of 10.2 tests
 #
diff --git a/mysql-test/r/range_mrr_icp.result b/mysql-test/r/range_mrr_icp.result
index cdaaa5e8ab7..fe4eb99f31f 100644
--- a/mysql-test/r/range_mrr_icp.result
+++ b/mysql-test/r/range_mrr_icp.result
@@ -1276,7 +1276,7 @@ SELECT * FROM t1 WHERE
 5 <= a AND b = 3 OR
 3 <= a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	a	a	5	NULL	3	Using where; Using index
+1	SIMPLE	t1	range	a	a	5	NULL	4	Using where; Using index
 SELECT * FROM t1 WHERE
 3 <= a AND a <= 5 OR 
 5 <= a AND b = 3 OR
@@ -3066,78 +3066,6 @@ a	b
 set eq_range_index_dive_limit=default;
 drop table t1;
 #
-# MDEV-23811: Both disjunct of WHERE condition contain range conditions
-#             for the same index such that the second range condition
-#             fully covers the first one. Additionally one of the disjuncts
-#             contains a range condition for the other index.
-#
-create table t1 (
-pk int primary key auto_increment, a int, b int,
-index idx1(a), index idx2(b)
-);
-insert into t1(a,b) values
-(5,50), (1,10), (3,30), (7,70), (8,80), (4,40), (2,20), (6,60);
-insert into t1(a,b) select a+10, b+100 from t1;
-insert into t1(a,b) select a+20, b+200 from t1;
-insert into t1(a,b) select a+30, b+300 from t1;
-insert into t1(a,b) select a,b from t1;
-analyze table t1;
-Table	Op	Msg_type	Msg_text
-test.t1	analyze	status	OK
-explain select * from t1 where ((a between 3 and 4) and b < 100) or (a between 2 and 5);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	idx1,idx2	idx1	5	NULL	11	Using index condition; Using where; Rowid-ordered scan
-select * from t1 where ((a between 3 and 4) and b < 100) or (a between 2 and 5);
-pk	a	b
-1	5	50
-3	3	30
-6	4	40
-7	2	20
-65	5	50
-67	3	30
-70	4	40
-71	2	20
-explain select * from t1 where (a between 2 and 5) or ((a between 3 and 4) and b < 100);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	idx1,idx2	idx1	5	NULL	11	Using index condition; Using where; Rowid-ordered scan
-select * from t1 where (a between 2 and 5) or ((a between 3 and 4) and b < 100);
-pk	a	b
-1	5	50
-3	3	30
-6	4	40
-7	2	20
-65	5	50
-67	3	30
-70	4	40
-71	2	20
-explain select * from t1 where (a between 3 and 4) or ((a between 2 and 5) and b < 100);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	idx1,idx2	idx1	5	NULL	11	Using index condition; Using where; Rowid-ordered scan
-select * from t1 where (a between 3 and 4) or ((a between 2 and 5) and b < 100);
-pk	a	b
-1	5	50
-3	3	30
-6	4	40
-7	2	20
-65	5	50
-67	3	30
-70	4	40
-71	2	20
-explain select * from t1 where ((a between 2 and 5) and b < 100) or (a between 3 and 4);
-id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	idx1,idx2	idx1	5	NULL	11	Using index condition; Using where; Rowid-ordered scan
-select * from t1 where ((a between 2 and 5) and b < 100) or (a between 3 and 4);
-pk	a	b
-1	5	50
-3	3	30
-6	4	40
-7	2	20
-65	5	50
-67	3	30
-70	4	40
-71	2	20
-drop table t1;
-#
 # End of 10.2 tests
 #
 set optimizer_switch=@mrr_icp_extra_tmp;
diff --git a/mysql-test/r/range_vs_index_merge_innodb.result b/mysql-test/r/range_vs_index_merge_innodb.result
index 916c30bb770..581f512768c 100644
--- a/mysql-test/r/range_vs_index_merge_innodb.result
+++ b/mysql-test/r/range_vs_index_merge_innodb.result
@@ -369,7 +369,7 @@ WHERE ((ID < 200) AND (Name LIKE 'Ha%' OR (Country > 'A' AND Country < 'ARG')))
 OR ((ID BETWEEN 100 AND 200) AND 
 (Name LIKE 'Pa%' OR (Population > 103000 AND Population < 104000)));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	City	range	PRIMARY,Population,Country,Name	PRIMARY	4	NULL	200	Using where
+1	SIMPLE	City	index_merge	PRIMARY,Population,Country,Name	Name,Population,PRIMARY	39,4,4	NULL	307	Using sort_union(Name,Population,PRIMARY); Using where
 SELECT * FROM City USE INDEX ()
 WHERE ((ID < 10) AND (Name LIKE 'H%' OR (Country > 'A' AND Country < 'ARG')))
 OR ((ID BETWEEN 100 AND 110) AND 
diff --git a/mysql-test/t/range.test b/mysql-test/t/range.test
index 0d2fbe24835..67d876d5f10 100644
--- a/mysql-test/t/range.test
+++ b/mysql-test/t/range.test
@@ -2096,48 +2096,6 @@ set eq_range_index_dive_limit=default;
 drop table t1;
 
 --echo #
---echo # MDEV-23811: Both disjunct of WHERE condition contain range conditions
---echo #             for the same index such that the second range condition
---echo #             fully covers the first one. Additionally one of the disjuncts
---echo #             contains a range condition for the other index.
---echo #
-
-create table t1 (
-  pk int primary key auto_increment, a int, b int,
-  index idx1(a), index idx2(b)
-);
-insert into t1(a,b) values
-  (5,50), (1,10), (3,30), (7,70), (8,80), (4,40), (2,20), (6,60);
-insert into t1(a,b) select a+10, b+100 from t1;
-insert into t1(a,b) select a+20, b+200 from t1;
-insert into t1(a,b) select a+30, b+300 from t1;
-insert into t1(a,b) select a,b from t1;
-
-analyze table t1;
-
-let $q1=
-select * from t1 where ((a between 3 and 4) and b < 100) or (a between 2 and 5);
-eval explain $q1;
-eval $q1;
-
-let $q2=
-select * from t1 where (a between 2 and 5) or ((a between 3 and 4) and b < 100);
-eval explain $q2;
-eval $q2;
-
-let $q3=
-select * from t1 where (a between 3 and 4) or ((a between 2 and 5) and b < 100);
-eval explain $q3;
-eval $q3;
-
-let $q4=
-select * from t1 where ((a between 2 and 5) and b < 100) or (a between 3 and 4);
-eval explain $q4;
-eval $q4;
-
-drop table t1;
-
---echo #
 --echo # End of 10.2 tests
 --echo #
 
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index cd58202ef5f..e933d2af355 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -1852,9 +1852,6 @@ SEL_ARG::SEL_ARG(SEL_ARG &arg) :Sql_alloc()
   next_key_part=arg.next_key_part;
   max_part_no= arg.max_part_no;
   use_count=1; elements=1;
-  next= 0;
-  if (next_key_part)
-    ++next_key_part->use_count;
 }
 
 
@@ -8872,15 +8869,9 @@ tree_or(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2)
   }
   bool no_imerge_from_ranges= FALSE;
 
-  SEL_TREE *rt1= tree1;
-  SEL_TREE *rt2= tree2;
   /* Build the range part of the tree for the formula (1) */ 
   if (sel_trees_can_be_ored(param, tree1, tree2, &ored_keys))
   {
-    if (no_merges1)
-      rt1= new SEL_TREE(tree1, TRUE, param);
-    if (no_merges2)
-      rt2= new SEL_TREE(tree2, TRUE, param);
     bool must_be_ored= sel_trees_must_be_ored(param, tree1, tree2, ored_keys);
     no_imerge_from_ranges= must_be_ored;
 
@@ -8938,6 +8929,12 @@ tree_or(RANGE_OPT_PARAM *param,SEL_TREE *tree1,SEL_TREE *tree2)
   else if (!no_ranges1 && !no_ranges2 && !no_imerge_from_ranges)
   {
     /* Build the imerge part of the tree for the formula (1) */
+    SEL_TREE *rt1= tree1;
+    SEL_TREE *rt2= tree2;
+    if (no_merges1)
+      rt1= new SEL_TREE(tree1, TRUE, param);
+    if (no_merges2)
+      rt2= new SEL_TREE(tree2, TRUE, param);
     if (!rt1 || !rt2 ||
         result->merges.push_back(imerge_from_ranges) ||
         imerge_from_ranges->or_sel_tree(param, rt1) ||
@@ -9600,11 +9597,10 @@ key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2)
 
       if (!tmp->next_key_part)
       {
-	SEL_ARG *key2_next= key2->next;
         if (key2->use_count)
 	{
 	  SEL_ARG *key2_cpy= new SEL_ARG(*key2);
-          if (!key2_cpy)
+          if (key2_cpy)
             return 0;
           key2= key2_cpy;
 	}
@@ -9625,7 +9621,7 @@ key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2)
             Move on to next range in key2
           */
           key2->increment_use_count(-1); // Free not used tree
-          key2=key2_next;
+          key2=key2->next;
           continue;
         }
         else