Microsoft® SQL Server® 2012 Bible

1097

CHAPTER

48

Data Compression

IN THIS CHAPTER

Understanding Compression

Reducing I/O

Applying Database Compression Procedures

Learning Compression Strategies

P

ushing a database into the tens of thousands of transactions per second requires massive

amounts of raw I/O performance. At those rates, today’s servers can supply the CPU and mem-

ory, but I/O struggles. By reducing the raw size of the data, data compression trades I/O for

CPU, improving performance.

SQL Server 2008 introduced data compression. Unfortunately, it was not as widely publicized as you

might anticipate. This could be because it is only available in the Enterprise Edition of SQL Server.

However, it is an important feature that offers tremendous benefi ts, and it’s easy to enable.

In other words, data compression doesn’t warrant an entire chapter because of its complexity or

length, but because of its value. Its impact is such that it deserves center stage, at least for this

chapter.

Understanding Data Compression

Every IT professional is familiar with data compression, such as zip fi les and .jpg compression, to

name a couple of popular compression technologies.

But SQL Server data compression is specifi c to the SQL Server storage engine and has a few

database-specifi c requirements. First, there must be zero risk of loss of data fi delity. Second, it

must be completely transparent — enabled without any application code changes.

SQL Server data compression isn’t like .jpg compression, where you can choose the level of compres-

sion and more compression means more data loss. With SQL Server data compression, the data is

transparently compressed by the storage engine, and every compressed data page retains every data

value when decompressed.

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