Expected Compression Ratios

HCC can provide very impressive compression ratios. The marketing material has claimed 10× compression ratios and believe it or not, this is actually a very achievable number for many datasets. Of course the amount of compression depends heavily on the data and which of the four algorithms is applied. The best way to determine what kind of compression can be achieved on your dataset is to test it. Oracle also provides a utility (often referred to as the Compression Advisor) to compress a sample of data from a table in order to calculate an estimated compression ratio. This utility can even be used on non-Exadata platforms as long as they are running 11.2.0.2 or later. This section will provide some insight into the Compression Advisor and ....