The purpose of this module is to enable the storage of history in Redis lists with increased precision, thanks to its finer control over fields, optional compression, and out-of-the-box cluster support.
This module stores keys as follows:
_zst if history is compressedIn addition, there is a special set where suffixes are stored, and the keyname for this set is simply key_prefix. For example, if there is a host example.local and it stores compressed history entries, it will save the following element if key_prefix is set: example.local_zst.
Rspamd uses zstd compression, which is highly efficient for both compression and decompression, offering a typical compression rate of 50% for history elements. As long as you have sufficient computational power, it is recommended to use zstd in order to minimize Redis memory usage when storing elements.
The Web Interface automatically recognises that history is stored in Redis and loads it appropriately.
The configuration of this module is pretty straightforward (use local.d/history_redis.conf to define your own values):
servers = 127.0.0.1:6379; # Redis server to store history
expire = 432000; # Expire in seconds for inactive keys, default to 5 days
nrows = 200; # Default rows limit
compress = true; # Use zstd compression when storing data in Redis
subject_privacy = false; # Subject privacy is off
Note: Reducing the expire value can result in a one-time situation where newer entries are deleted before older ones, creating a gap in the middle of the history.