MDEV-23878 Wrong result with semi-join and splittable derived table

Due to this bug a wrong result might be expected from queries with
an IN subquery predicate in the WHERE clause and a derived table in the
FROM clause to which split optimization could be applied.

The function JOIN::fix_all_splittings_in_plan() used the value of the
bitmap JOIN::sjm_lookup_tables() such as it had been left after the
search for the best plan for the select containing the splittable
derived table. That value could not be guaranteed to be correct. So the
recalculation of this bitmap is needed to exclude the plans with key
accesses from SJM lookup tables.

Approved by Igor Babaev <igor@maridb.com>

mysql-test/main/derived_split_innodb.result

@@ -848,4 +848,61 @@ SELECT * FROM t1 WHERE t1.a IN (SELECT b FROM
 (SELECT t2.b FROM t2 WHERE NOT EXISTS (SELECT 1 FROM t3) GROUP BY b) sq);
 a
 DROP TABLE t1, t2, t3;
+#
+# MDEV-23878: Wrong result with semi-join and splittable derived table
+#
+CREATE TABLE t1 (
+groupId int,
+id int unsigned,
+PRIMARY KEY (groupId, id)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+INSERT INTO t1 VALUES
+(8,1),(8,2),(8,3),(8,4),(8,5),(8,6),(8,7),(8,8),(8,9),(8,10),
+(8,11),(8,12),(8,13),(8,14),(8,15),(8,16),(8,17),(8,18),(8,19);
+set statement in_predicate_conversion_threshold=2 for SELECT COUNT(*) AS cnt FROM t1
+JOIN
+(
+SELECT groupId, id
+FROM t1
+WHERE id IN (1,2,3,4,5,6)
+GROUP BY groupId, id
+) AS t2
+USING (groupId, id)
+WHERE id IN (1,2,3,4,5,6,7,8);
+cnt
+6
+set statement in_predicate_conversion_threshold=2 for EXPLAIN SELECT COUNT(*) AS cnt FROM t1
+JOIN
+(
+SELECT groupId, id
+FROM t1
+WHERE id IN (1,2,3,4,5,6)
+GROUP BY groupId, id
+) AS t2
+USING (groupId, id)
+WHERE id IN (1,2,3,4,5,6,7,8);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	index	PRIMARY	PRIMARY	8	NULL	19	Using index
+1	PRIMARY	<subquery4>	eq_ref	distinct_key	distinct_key	4	func	1	Using where
+1	PRIMARY	<derived3>	ref	key0	key0	8	test.t1.groupId,test.t1.id	2	
+4	MATERIALIZED	<derived5>	ALL	NULL	NULL	NULL	NULL	8	
+5	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+3	LATERAL DERIVED	t1	eq_ref	PRIMARY	PRIMARY	8	test.t1.groupId,test.t1.id	1	Using index
+3	LATERAL DERIVED	<derived7>	ref	key0	key0	4	test.t1.id	2	Using where; FirstMatch(t1)
+7	DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
+set statement optimizer_switch='split_materialized=off, loosescan=off' for
+set statement in_predicate_conversion_threshold=2 for
+SELECT COUNT(*) AS cnt FROM t1
+JOIN
+(
+SELECT groupId, id
+FROM t1
+WHERE id IN (1,2,3,4,5,6)
+GROUP BY groupId, id
+) AS t2
+USING (groupId, id)
+WHERE id IN (1,2,3,4,5,6,7,8);
+cnt
+6
+DROP TABLE t1;
 # End of 10.4 tests

mysql-test/main/derived_split_innodb.test

@@ -503,4 +503,46 @@ SELECT * FROM t1 WHERE t1.a IN (SELECT b FROM
 
 DROP TABLE t1, t2, t3;
 
+--echo #
+--echo # MDEV-23878: Wrong result with semi-join and splittable derived table
+--echo #
+
+CREATE TABLE t1 (
+  groupId int,
+  id int unsigned,
+  PRIMARY KEY (groupId, id)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1;
+
+INSERT INTO t1 VALUES
+  (8,1),(8,2),(8,3),(8,4),(8,5),(8,6),(8,7),(8,8),(8,9),(8,10),
+  (8,11),(8,12),(8,13),(8,14),(8,15),(8,16),(8,17),(8,18),(8,19);
+
+let $query=
+SELECT COUNT(*) AS cnt FROM t1
+JOIN
+(
+  SELECT groupId, id
+  FROM t1
+  WHERE id IN (1,2,3,4,5,6)
+  GROUP BY groupId, id
+) AS t2
+USING (groupId, id)
+WHERE id IN (1,2,3,4,5,6,7,8);
+
+let $tvc_conversion_threshold =
+  set statement in_predicate_conversion_threshold=2 for;
+
+eval $tvc_conversion_threshold $query;
+eval $tvc_conversion_threshold EXPLAIN $query;
+
+let $no_split_materialized_loosescan=
+  set statement optimizer_switch='split_materialized=off, loosescan=off' for;
+
+# Correct result with split materializied optimization disabled
+eval $no_split_materialized_loosescan
+  $tvc_conversion_threshold
+  $query;
+
+DROP TABLE t1;
+
 --echo # End of 10.4 tests

sql/opt_split.cc

@@ -1332,6 +1332,7 @@ bool JOIN::fix_all_splittings_in_plan()
 {
   table_map prev_tables= 0;
   table_map all_tables= (table_map(1) << table_count) - 1;
+  table_map prev_sjm_lookup_tables= 0;
   for (uint tablenr= 0; tablenr < table_count; tablenr++)
   {
     POSITION *cur_pos= &best_positions[tablenr];
@@ -1340,7 +1341,7 @@ bool JOIN::fix_all_splittings_in_plan()
     {
       SplM_plan_info *spl_plan= cur_pos->spl_plan;
       table_map excluded_tables= (all_tables & ~prev_tables) |
-                                 sjm_lookup_tables;
+                                 prev_sjm_lookup_tables;
                                    ;
       if (spl_plan)
       {
@@ -1358,6 +1359,8 @@ bool JOIN::fix_all_splittings_in_plan()
           return true;
     }
     prev_tables|= tab->table->map;
+    if (cur_pos->sj_strategy == SJ_OPT_MATERIALIZE)
+        prev_sjm_lookup_tables|= tab->table->map;
   }
   return false;
 }