Online Transaction Processing Systems Research Articles

Database buffer size investigation for OLTP workloads

It is generally accepted that On-Line Transaction Processing (OLTP) systems benefit from large database memory buffers. As enterprise database systems become larger and more complex, hardware vendors are building increasingly large systems capable of supporting huge memory configurations. Database vendors in turn are developing buffer schemes to exploit this physical memory. How much will these developments benefit OLTP workloads? Through empirical studies on databases sized comparably to those seen in the real-world, this paper presents the characteristics of an industry-standard OLTP benchmark as memory buffer size changes. We design the experiments to investigate how the database size, the buffer size and the number of CPUs impact performance, in particular the throughput and the buffer hit rate on Symmetric Multiprocessor Systems. The relationships of these major database attributes are plotted and key observations are summarized. We discuss how these relationships change as the number of CPUs changes. We further quantify the relationships: 1) between database buffer data hit rate, buffer size and database size, 2) between throughput, buffer data hit rate and database size and 3) between throughput and number of CPUs. Algorithms, rules-of-thumb and examples are presented for predicting performance, sizing memory and making trade-offs between adding more memory and increasing the number of CPUs.

Intelligent storage devices for scalable information management systems

For most large commercial organisations the ability to store and manipulate massive volumes of data is a key operational requirement. Database systems are fundamental to the efficient provision of a range of business tasks from on-line transaction processing, decision support and enterprise information systems. High performance multiprocessor database servers open up new possibilities for the realisation of these commercial requirements. If these opportunities are to be realised intelligent storage devices will be required to provide a uniform interface regardless of implementation and which also directly supports the basic need of scalability. In this paper we explore some of the issues for such a device.

Distributed decision support and organizational connectivity: A case study

While the Internet has been grabbing most of the attention of the information systems researchers and practitioners, online transaction processing systems still take the lion's share of business information systems. Although many Decision Support Systems (DSS) have been developed, they failed to become mainstream products due to their limited availability, applicability, and interoperability. In this paper, we propose a script language to make use of the vast resource of the Internet as a means (i) to better make DSS known to potential users, and (ii) to allow construction of DSS from DSS components stored on various Internet sites. With the proposed script language, we contend that DSS would have a greater potential of gaining a larger share of use among the business community. Contrasting to other approaches that advocate for a central clearinghouse of DSS components, we propose a bottom-up strategy, i.e., users and developers of DSS's cooperate in weaving a web of distributed DSS components to form a federated network of on-line DSS repositories. The purpose of the proposed script language is to ensure effective search of DSS components and rapid development and deployment of application-specific DSS. The proposed method is scalable to support distributed platforms using multiple processors and/or application domains. A case study derived from a real life application in a multi-national company is discussed to illustrate the proposed approach.

Probabilistic quorum protocols for biometrical user authentication in OLTP

A statistical zero-knowledge authentication scheme is described for security control in on-line database transaction processing systems (OLTP). This scheme uses probabilistic quorum protocols to validate users using their biometrical characteristics (such as speech, handwriting and keyboard characteristics). This authentication scheme can be implemented using the present-day smart card technology.

Knowledge-based security control for on-line database transaction processing systems

This paper considers the interrelationships between knowledge-based security, concurrency and recoverability in online database transaction processing systems (OLTP). We describe how OLTP can permit the users to carry out the desired actions, and concurrently activate scrutinizing transactions that identify the users with respect to their biometrical or other characteristics stored in a secure knowledge database. A finite state machine model is used to design protocols for recovery, under security breaches. It is shown that the best way to achieve concurrency and recovery in OLTP is through shadowing and strict-scheduling in conjunction with certification locking or timestamping. We must, however, bear in mind that security and concurrency have conflicting requirements and at best we can achieve a compromise between them.

Efficient demultiplexing of incoming TCP packets

When a transport protocol segment arrives at a receiving system, the receiving system must determine which application is to receive the protocol segment. This decision is typically made by looking up a protocol control block (PCB) for the segment, based on information in the segment's header. PCB lookup (a form of demultiplexing) is typically one of the more expensive operations in handling inbound protocol segment [Fe190]. Many recent protocol optimizations for the Transmission Control Protocol (TCP) [Jac88] assume that a large component of TCP traffic is bulk-data transfers, which result in packet trains [JR86]. If packet trains are prevalent, there is a high likelihood that the next TCP segment is en route to the same application (i.e. uses the same PCB) as the previous TCP segment. In these environments a very simple one-PCB cache like those used in BSD systems yields very high cache hit rates. However, there are classes of applications that do not form packet trains, and these applications do not perform well with a one-PCB cache. Examples of such applications are quite common in the area of heads-down data entry into on-line transaction-processing (OLTP) systems. OLTP systems make heavy use of computer communications networks and have large aggregate-packet-rates but are also characterized by large numbers of connections, low per-connection packet rates, and rather small packets. This combination of characteristics results in a very low incidence of packet trains. This paper uses a simple analytic approach to examine how different PCB lookup schemes perform with OLTP traffic. One scheme is shown to work an order of magnitude better for OLTP traffic than the one-PCB cache approach while still maintaining good performance for packet-train traffic.

SAA distributed file access to the CICS environment

IBM's Customer Information Control System (CICS) is the leading product family in the on-line transaction processing (OLTP) market. OLTP systems are being used by many enterprises to implement their daily business processes and manage operational data such as accounts, inventories, and orders. CICS/Distributed Data Management (CICS/DDM) implements the distributed file function of Systems Application Architecture® (SAA™) Common Communications Support in the CICS environment on Multiple Virtual Storage (MVS) and Virtual Storage Extended (VSE) operating systems. Providing a DDM target server, CICS/DDM implements IBM's SAA protocol for access to distributed data, which are exploited by the SAA Common Programming Interface. CICS/DDM allows applications and their users to access and share the data managed through the OLTP environment provided by CICS.

Incremental recovery in main memory database systems

Recovery activities, like checkpointing and restart, in traditional database management systems are performed in a quiescent state where no transactions are active. This approach impairs the performance of online transaction processing systems, especially when a large volatile memory is used. An incremental scheme for performing recovery in main memory database systems (MMDBs), in parallel with transaction execution, is presented. A page-based incremental restart algorithm that enables the resumption of transaction processing as soon as the system is up is proposed. Pages are recovered individually and according to the demands of the post-crash transactions. A method for propagating updates from main memory to the backup database on disk is also provided. The emphasis is on decoupling the I/O activities related to the propagation to disk from the forward transaction execution in memory. The authors also construct a high-level recovery manager based on operation logging on top of the page-based algorithms. The proposed algorithms are motivated by the characteristics of large MMDBs, and exploit the technology of nonvolatile RAM.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Book review: Performance Measurement of Computer Systems by Phillip McKerrow (Addison-Wesley 1988)

As its title indicates, this book has the very specific purpose of applying performance evaluation tools to the study of on-line transaction processing systems. The book provides both an overview of the relevant mathematical methods from performance evaluation, and an application of those methods to transaction processing systems.