MDEV-9635: Server crashes in part_of_refkey or assertion `!created && key_to_save < (int)s->keys' failed in TABLE::use_index(int) or with join_cache_level>2

Do not try to create index where ref is for hash join.

Author: sanja-byelkin

mysql-test/r/subselect_innodb.result

@@ -454,3 +454,18 @@ HAVING SQ2_alias1 . col_int_key >= 7
 1
 drop table t1;
 set optimizer_switch=@subselect_innodb_tmp;
+#
+# MDEV-9635:Server crashes in part_of_refkey  or assertion
+# `!created && key_to_save < (int)s->keys' failed in
+# TABLE::use_index(int) or with join_cache_level>2
+#
+SET join_cache_level=3;
+CREATE TABLE t1 (f1 VARCHAR(1024)) ENGINE=InnoDB;
+CREATE ALGORITHM=TEMPTABLE VIEW v1 AS SELECT * FROM t1;
+CREATE TABLE t2 (f2 VARCHAR(4)) ENGINE=InnoDB;
+INSERT INTO t2 VALUES ('foo'),('bar');
+SELECT * FROM v1, t2 WHERE ( f1, f2 ) IN ( SELECT f1, f1 FROM t1 );
+f1	f2
+set join_cache_level = default;
+drop view v1;
+drop table t1,t2;

mysql-test/t/subselect_innodb.test

@@ -433,3 +433,23 @@ drop table t1;
 
 
 set optimizer_switch=@subselect_innodb_tmp;
+
+--echo #
+--echo # MDEV-9635:Server crashes in part_of_refkey  or assertion
+--echo # `!created && key_to_save < (int)s->keys' failed in
+--echo # TABLE::use_index(int) or with join_cache_level>2
+--echo #
+
+SET join_cache_level=3;
+
+CREATE TABLE t1 (f1 VARCHAR(1024)) ENGINE=InnoDB;
+CREATE ALGORITHM=TEMPTABLE VIEW v1 AS SELECT * FROM t1;
+
+CREATE TABLE t2 (f2 VARCHAR(4)) ENGINE=InnoDB;
+INSERT INTO t2 VALUES ('foo'),('bar');
+
+SELECT * FROM v1, t2 WHERE ( f1, f2 ) IN ( SELECT f1, f1 FROM t1 );
+
+set join_cache_level = default;
+drop view v1;
+drop table t1,t2;

sql/sql_select.cc

@@ -9422,7 +9422,7 @@ void JOIN::drop_unused_derived_keys()
       continue;
     if (!table->pos_in_table_list->is_materialized_derived())
       continue;
-    if (table->max_keys > 1)
+    if (table->max_keys > 1 && !tab->is_ref_for_hash_join())
       table->use_index(tab->ref.key);
     if (table->s->keys)
     {