The designer of an OLTP system must ensure that the number of concurrent users does not interfere with the performance of the system. Some key elements include rollback segments (which record actions of transactions to enable rollback if needed); clusters (data schema which which improves performance of join operations); discrete transactions (ensures the data is not changed until the transaction is committed, which improves performance); block size (reduces unnecessary I/O by ensuring data block size is a multiple of operating system block size); buffer cache size (when SQL statements are tuned to use buffer cache, it avoids unnecessary consumption); dynamic allocation of space to tables and rollback segments; transaction processing monitors (used for coordination of services, acting as kind of an operating system that can span multiple computing devices); database partitions (using partitions increases performance while balancing availability and security); and database tuning (allowing the OLTP system to maximize its performance efficiently and rapidly).