Multivalue compression (MVC) compresses repeating values in a column when you specify the value in a compression list in the column definition.
When data in the column matches a value in the compression list, the database stores the value once in the table header, regardless of the number of times the value occurs in the column. The database then stores a smaller substitute value, often as small as 2 bits, in each row where the value occurs.
MVC typically provides a better cost/benefit ratio than other methods. Because MVC requires minimal resources to uncompress the data during query processing, you can use MVC for hot (frequently used) data without compromising query/load performance. MVC is also considered the easiest to implement of all the compression methods.
MVC is a logical data compression form and is lossless.
- Improves table scan response times for most configurations and workloads
- Provides moderate to little CPU savings