The What, How, and Why of DB2 Accelerators
Direct answers to the most important questions about DB2 accelerators
DB2 for z/OS is celebrating its 30th anniversary this year. When released, DB2 was designed to serve as a data warehouse. With time and development, DB2 evolved into the state-of-the-art Online Transaction Processing (OLTP) and data warehousing engine that we know today. But very few changes have impacted DB2 in its history as much as the introduction of acceleratrs. Accelerators integrate with existing DB2 for z/OS servers to create a hybrid database. Today, DB2 is a powerful software package that can deliver excellent performance for both transactional and analytic processing.
But what is a DB2 accelerator? How do accelerators work? And why you should consider an accelerator for your organization? This article will provide direct answers to the most frequent and fundamental questions that DB2 users are asking today.
What are DB2 accelerators?
A DB2 accelerator, or an accelerator for DB2 for z/OS queries, is a technical solution that executes SQL queries on behalf of DB2 for z/OS. It is designed to be a high-performance appliance. It can help some types of queries, such as those commonly found in business intelligence or analytic applications, run fast—sometimes much faster.
The very nature of the appliance concept provides transparent integration with DB2 for z/OS. An accelerator is not another database; it is an extension of DB2. The maintenance and administration tasks are done through DB2. Performance metrics are included in the traditional DB2 instrumentation facility, and there is no new user interface to learn.
Both isolation and integration are transparently exposed to end users as well. No application changes are necessary to accelerate eligible queries.
IBM announced the availability of IBM DB2 Analytics Accelerator for z/OS V3.1 (IDAA) in October 2012. In its third generation, IDAA provides improvements that significantly increase its business value. It provides an enhanced scope for query offload, meaning that more SQL is now eligible for acceleration. It supports low-latency incremental data updates, which makes recent changes available for acceleration. The new high-performance storage server feature helps to reduce disk storage costs by allowing you to store archive data on IDAA only, under DB2 control, where it can benefit from hyper-speed analytics processing.
How do DB2 accelerators work?
The IDAA appliance connects to z/OS and DB2 using a private network. The DB2 objects to be accelerated are defined and loaded in IDAA using DB2 stored procedures and a graphical user interface. Just configure a few settings and choices, and the installation is ready.
Once an accelerator is installed and activated, the DB2 optimizer treats the appliance as a new access path and will offload SQL processing transparently when it is more efficient to do so. Not every query may be accelerated. Some may have incompatible SQL statements, or the DB2 optimizer may decide that offload is not the optimal choice.* Alternatively, you can also configure the optimizer to send every eligible query to the accelerator—regardless of any costing or heuristic consideration.
Why you should consider using a DB2 accelerator?
Most of the business value of IDAA could be summarized in two key concepts: speed and cost savings. IDAA also helps deliver transparency for users and applications, and it is designed for fast and easy deployment.
The potential benefits of IDAA can be estimated before purchasing and installation. A study based on the information provided by the DB2 dynamic SQL statement cache can help you assess the SQL queries and the processor that would be offloaded if you deployed an accelerator. You can use a virtual accelerator in combination with EXPLAIN to understand how your queries would behave with a real accelerator. For example, the DSN_QUERYINFO_TABLE table provides reasons why ineligible queries are not eligible, as well as information about accelerated queries.
IDAA helps transform DB2 into a state-of-the-art transactional and analytic database engine while minimizing installation and maintenance efforts. By accelerating SQL queries in a way that is transparent to applications, IDAA can provide both high performance and a reduction in total cost of ownership (TCO).
Have you considering using IDAA in your organization? How has it changed your operations? Let me know—or leave your questions—in the comments.
* For more information, see “Optmizing DB2 Queries with IBM DB2 Analytics Accelerator for z/OS,” IBM Redbooks, August 2012.
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