Compression as a lever: the answer depends on the billing clause
Why does one billing clause decide whether to compress harder or less?
The decision is the compression ratio against the CPU you pay for on each read. The right answer depends on which side of the meter the CPU sits on.
| Billing clause | Who pays for decompression CPU? | Best compression strategy |
|---|---|---|
| CPU- or occupancy-metered compute | You, on every read | Optimal codec strength falls as read frequency rises: heavy codecs for cold archives, fast codecs for hot data |
| Scan-metered compute (billed per byte scanned, compressed) | The vendor | Inverts: compress as hard as the format allows, hot data most of all |
| Scan-metered, but bytes counted uncompressed | The vendor | Compression has no scan value, only storage value: back to the cold-archive case |
Same data, same engine, same physics, three different correct answers, decided by one clause in the contract. This is this mechanism's central point in its cleanest form. The design sign flips at a discontinuity at a contract line, not through a gradual change.