if (NULL == table_items)
	{
		table_items = DBget_table("items");

		/* do not update existing lastlogsize and mtime fields */
		zbx_vector_ptr_create(&skip_fields);
		zbx_vector_ptr_append(&skip_fields, (void *)DBget_field(table_items, "lastlogsize"));
		zbx_vector_ptr_append(&skip_fields, (void *)DBget_field(table_items, "mtime"));
		zbx_vector_ptr_sort(&skip_fields, ZBX_DEFAULT_PTR_COMPARE_FUNC);
	}