Data compression lets you use less storage space for the same amount of data, reduce cache memory consumption, and improve performance because of lower I/O demands.
You can compress large object (LOB) and regular data.
Adaptive Server® provides different levels of compression for regular and LOB data. Generally, higher compression ratios use more CPU when you decompress the data. Select compression levels based on how the data is accessed. Data that you access frequently ("hot data") may be best suited for compression levels that have smaller CPU overhead.
After you create a compressed table or partition, Adaptive Server compresses any subsequently inserted or updated data (that is, existing data is not already compressed). If Adaptive Server cannot efficiently compress the inserted data, the original row is retained. If newly inserted or updated LOB data occupies space that is smaller than or equal to a single data page, Adaptive Server does not compress this data.
Tables can be a mixture of compressed and uncompressed data. For example, if you create a compressed table, load data, then disable data compression for the table, previously inserted data is compressed, but rows added after you disable compression are not compressed.
You need not uncompress data to run queries against it. You can insert, update, and delete compressed data; running select or readtext statements on the compressed column returns decompressed rows. Because there is less data for Adaptive Server to search, there are fewer I/Os, improving the efficiency of data storage.