MDEV-13153: Assertion ... failed on partitioned RocksDB table

ha_partition creates temporary ha_XXX objects for its partitions when
performing DDL operations. The objects were created on a MEM_ROOT and
never deleted.
This works as long as ha_XXX objects free all data ha_XXX::close() and
don't rely on a proper destructor invocation. Unfortunately, ha_rocksdb
includes String members which need to be delete'd properly.

Fixed the bug by having ha_partition::~ha_partition delete these temporary
objects.

sql/ha_partition.cc

@@ -413,8 +413,12 @@ ha_partition::~ha_partition()
   destroy_record_priority_queue();
   my_free(m_part_ids_sorted_by_num_of_records);
 
+  if (m_added_file)
+  {
+    for (handler **ph= m_added_file; *ph; ph++)
+      delete (*ph);
+  }
   clear_handler_file();
-
   free_root(&m_mem_root, MYF(0));
 
   DBUG_VOID_RETURN;

storage/rocksdb/mysql-test/rocksdb/r/rocksdb_parts.result

@@ -121,3 +121,14 @@ t2
 DROP TABLE t2;
 use test;
 DROP DATABASE db3;
+#
+# MDEV-13153 Assertion `global_status_var.global_memory_used == 0 ' 
+#            failed upon server restart with partitioned RocksDB table
+#
+CREATE TABLE t1 (a INT) ENGINE=RocksDB PARTITION BY HASH(a) PARTITIONS 2;
+INSERT INTO t1 (a) VALUES (1),(2);
+ALTER TABLE t1 ADD PARTITION PARTITIONS 2;
+SELECT 1;
+1
+1
+DROP TABLE t1;

storage/rocksdb/mysql-test/rocksdb/t/rocksdb_parts.test

@@ -120,3 +120,14 @@ DROP TABLE t2;
 use test;
 DROP DATABASE db3;
 
+--echo #
+--echo # MDEV-13153 Assertion `global_status_var.global_memory_used == 0 ' 
+--echo #            failed upon server restart with partitioned RocksDB table
+--echo #
+CREATE TABLE t1 (a INT) ENGINE=RocksDB PARTITION BY HASH(a) PARTITIONS 2;
+INSERT INTO t1 (a) VALUES (1),(2);
+ALTER TABLE t1 ADD PARTITION PARTITIONS 2;
+--source include/restart_mysqld.inc
+SELECT 1;
+DROP TABLE t1;
+