Features

• Support offset and limit for recommendation result fetching (#287).
• Support insert feedback with future timestamps (#283).
• Support write-back-delay for recommendation result fetching (#283).
• Support prometheus metrics for master, worker, server and database (#289).
• Support write logs to files (#289).
• Support multiple read feedback types (#288).
• Support custom location for local cache (#292).

Performance

• Replace encoding/gob with custom encoder/decoder (#284).
• Replace message based model distribution with stream based protocol (#284).
• Add index for item_id in feedback table (#286).

Fix

• Fix unclosed result sets in database interfaces (#275).

Upgrade Guide

• In configuration file, read_feedback_type has been replaced by read_feedback_types, which is an array of strings.
• In recommendation API:
  • write-back has been replaced by write-back-type.
  • Use write-back-delay to set delayed timestamps of write back feedbacks.
  • Use offset to load paged recommendation results.
• In command line:
  • Use --log-path to specify the path of logging file.
  • Use --cache-path to specify the path of local cache file.