Living in memory
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Economic factors have made in-memory database systems more accessible
Will in-memory databases entirely replace their disk-based forebears?
The database is the workhorse of corporate IT systems and for over 35 years the hard disk has been its stable. But some technologists believe that as a platform for enterprise databases, disk-based storage has had its day.
For one thing, they argue, modern business applications demand response times measured in nanoseconds, but the process of reading and writing data to and from a disk puts the brake on database performance.
What is more, to ensure adequate throughput and to relieve stress on individual disk heads, database administrators must scatter data across volumes of individual disks. According to IDC analyst Carl Olofson, individual disks used in this way typically have utilisation rates of just 40% to 50%. This increases the energy needs of a storage array, compromising the overall energy efficiency of the data centre.
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Add to this the physical bulk of disk media, and it is easy to see why businesses are looking for an alternative database platform.
As it happens, an alternative has long been available.
In-memory databases, or IMDBs, reside entirely in the main memory of a server. This removes the mechnical process of reading and writing data to disk, therefore accelerating database operations.
IMDBs are not uncommon. They are often used for database caching (storing frequently requested data in memory for faster access), in specialised high-speed applications for the telecommunications, financial and defence markets and, increasingly, in certain business intelligence (BI) systems.
But three recent developments in server technology have boosted the viability of IMDBs in mainstream IT. These are 64-bit computing, which makes more of a server’s main memory addressable; multi-core servers; and, above all, the falling cost of RAM [random access memory] chips. Today, 1GB of RAM can cost less than $35, compared to $150 just a few years ago. “All this means that the economics of computing have swung in favour of in-memory databases for many workloads,” says Olofson.
In-memory intelligence
Beyond specialised applications, the most common application for IMDBs has so far been BI and analytics systems.
Different in-memory BI tools apply the technology in different ways. Some extract data from a source system or data warehouse in advance before loading it into memory for manipulation by the user.
Others, such as Qlikview from Qliktech, eliminate disk access altogether by building entire data marts in memory. This dramatically accelerates the speed of reports and analyses, which, according to Anthony Deighton, senior vice president of products at QlikTech, translates to accelerated decision-making in business.
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