Does Squid support deletions in Cache Digests? What are diffs/deltas?
Squid does not support deletions from the digest. Because of this the digest must, periodically, be rebuilt from scratch to erase stale bits and prevent digest pollution. A more sophisticated option is to use diffs or deltas. These would be created by building a new digest and comparing with the current/old one. They would essentially consist of aggregated deletions and additions since the previous digest. Since less bandwidth should be required using these it would be possible to have more frequent updates (and hence, more accurate information). Costs: • RAM – extra RAM needed to hold two digests while comparisons takes place. • CPU – probably a negligible amount.
