log retention policy issure

[张明富 <mi...@xtaotech.com>]

Hi,
  From kafka's document I found：
  "The Kafka cluster retains all published records—whether or not they have been consumed—using a configurable retention period. For example, if the retention policy is set to two days, then for the two days after a record is published, it is available for consumption, after which it will be discarded to free up space. Kafka's performance is effectively constant with respect to data size so storing data for a long time is not a problem."
  Is this mean once the retention hour is over all the messages will be discarded no matter consumed or not ? 
  There is a risk of missing logs for some consumers which are not subscribing messages in time.
  Now the log retention policy just contain "log.retention.hours" and "log.retention.bytes" is not enough.
  I hope kafka can consider the factor consumer's offset when purge the log segment file.
  Is this issure can be imporved in the future release?


  Good Day, Thanks!