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ParAccel flashes data warehouses

Thinking in columns

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ParAccel - one of the many upstarts that is chasing the data warehousing and analytics dollars these days - has tweaked its ParAccel Analytic Database 2.0 software and its underlying homegrown Linux operating system so that the x64 nodes on which it runs can be equipped with flash-based drives. And that, the company says, will boost query performance.

The ParAccel analytics database and the data warehousing clusters that are built using it are not just glorified relational databases that organize record information in rows and then scan it to do queries, but rather use a columnar format that organizes data by field. (The Sybase IQ database, which is used in several thousand data warehouses and which is distinct from the regular Adaptive Server relational database, also organizes data in columns).

Organizing relational databases by row is key for transaction processing, where you want to locate a record among zillions, read its data, and maybe modify it. But in a data warehouse, where you want to sort data and extract answers from the tables underlying the database, this row orientation gets in the way and slows everything down. Which is why Barry Zane, one of the founders of data warehousing appliance maker Netezza, left the company and started ParAccel in 2006.

Here's a simple example: Say you have a subset of the US census data with 10 different answers to questions stored in 10 fields in a relational database. Say each one has 10 bytes of data. In the row-oriented relational data warehouse, if you want to ask a question about the state and age of citizens, you have to scan all ten fields, for a total of 1,000 bytes.

But in a columnar database, you know you only want to look at the age and state columns, and you are only scanning 200 bytes to do a query. With the ParAccel database, you run the database in a shared-nothing, massively parallel cluster of servers with a mix of local server and remote SAN storage, and you can radically speed up table scans and queries as well as loading of data onto the database because everything is parallelized.

The addition of flash to PADB 2.0, which started shipping in June, doesn't boost performance as much as you might expect, and that's because of the clever things that the database already does with local and remote storage to goose performance. According to Kim Stanick, vice president of marketing at ParAccel, customers should expect about a 15 per cent performance boost if they add some flash drives to their x64 servers, and when the reduced power consumption is taken into account, they might see a 25 per cent increase in queries per watt. That's nothing to shake a stick at, but it is not the kind of performance improvement you would expect given the very high I/O rates of flash drives.

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