acardinale

-- The goal of this script is to trim messages that have been processed by
-- all extant groups from the a given Redis stream. It returns the number
-- of messages that were deleted from the stream, if any. I make no
-- guarantees about its performance, particularly if the stream is large
-- and not fully processed (so a simple XTRIM isn't possible).

-- First off, bail out early if the stream doesn't exist.
if redis.call("EXISTS", KEYS[1]) == 0 then
  return false
end