How are objects added to the Cache Digest in Squid?
Every object referenced in the index in RAM is checked to see if it is suitable for addition to the digest. A number of objects are not suitable, e.g. those that are private, not cachable, negatively cached etc. and are skipped immediately. A freshness test is next made in an attempt to guess if the object will expire soon, since if it does, it is not worthwhile adding it to the digest. The object is checked against the refresh patterns for staleness… Since Squid stores references to objects in its index using the MD5 key discussed earlier there is no URL actually available for each object – which means that the pattern used will fall back to the default pattern, “.”. This is an unfortunate state of affairs, but little can be done about it. A cd_refresh_pattern option will be added to the configuration file soon which will at least make the confusion a little clearer 🙂 Note that it is best to be conservative with your refresh pattern for the Cache Digest, i.e. do not add objects if
