Prefix compression stores a shared prefix once for repeated values in the same column on a page. It selects the longest complete prefix as an anchor, then stores other values as differences from that anchor. section 10.9
Within page compression, the process works as follows:
- Identify a common prefix among values in one column on a data page. section 10.9
- Store the longest complete prefix as an anchor. section 10.9
- Store remaining values as differentials from that anchor. section 10.9
- Track page changes through the CI record because updates can reduce compression effectiveness and trigger a rebuild decision. section 10.9
Applying page compression
Prefix compression is applied as part of page compression, for example by rebuilding ImpressionsArchive with ALTER TABLE ImpressionsArchive REBUILD WITH (DATA_COMPRESSION = PAGE). section 10.9
