MDEV-22185 Failing assertion: node->pcur->rel_pos == BTR_PCUR_ON or...

MDEV-22185 Failing assertion: node->pcur->rel_pos == BTR_PCUR_ON or ER_KEY_NOT_FOUND or Assertion `inited==NONE' failed in handler::ha_index_init

long unique checks should be done for a partitioned table as a whole,
not for individual partitions.

Followup for f3f31eaa that extends it to UPDATE

mysql-test/main/long_unique_bugs.result

@@ -337,3 +337,7 @@ a	b
 1	foo
 3	bar
 drop table if exists t1, t2;
+create table t1 (a int, b int, unique (b) using hash) engine=innodb partition by key (a) partitions 2;
+insert into t1 values (1,10),(2,20);
+update t1 set b = 30 limit 1;
+drop table t1;

mysql-test/main/long_unique_bugs.test

@@ -402,3 +402,11 @@ create or replace table t2 (a int, b blob, unique(b)) replace as select * from t
   select * from t2;
 
 drop table if exists t1, t2;
+
+#
+# MDEV-22185 Failing assertion: node->pcur->rel_pos == BTR_PCUR_ON or ER_KEY_NOT_FOUND or Assertion `inited==NONE' failed in handler::ha_index_init
+#
+create table t1 (a int, b int, unique (b) using hash) engine=innodb partition by key (a) partitions 2;
+insert into t1 values (1,10),(2,20);
+update t1 set b = 30 limit 1;
+drop table t1;

sql/handler.cc

@@ -7009,7 +7009,7 @@ int handler::ha_update_row(const uchar *old_data, const uchar *new_data)
   MYSQL_UPDATE_ROW_START(table_share->db.str, table_share->table_name.str);
   mark_trx_read_write();
   increment_statistics(&SSV::ha_update_count);
-  if (table->s->long_unique_table &&
+  if (table->s->long_unique_table && this == table->file &&
       (error= check_duplicate_long_entries_update(new_data)))
   {
     return error;