Sorting

There are several areas where reddit sorts objects coming back from their APIs in a way that isn’t necessarily trivial via standard django ORM methods. This list is meant to be comprehensive so we know the problem space:

• Hot (named “Active” in our UI)
  • A logarithmic sort, where as an item ages, it requires an order of magnitude more upvotes - downvotes to be sorted above a newer item, the interval for the order of magnitude increase is 12.5 hours
  • Implementation: https://github.com/mitodl/reddit/blob/stable/r2/r2/lib/db/_sorts.pyx#L47
• Confidence (named “Best” in our UI)
  • Items are sorted with a weighted algorithm
  • See the corresponding code in the reddit source:
    • https://github.com/mitodl/reddit/blob/stable/r2/r2/lib/db/_sorts.pyx#L70
    • https://github.com/mitodl/reddit/blob/stable/install/setup_postgres.sh#L42
• New - posts are sorted in reverse chronological order
• old - posts are sorted in chronological order

Posts

Posts are sorted in two places: channels and the frontpage. These both support seemingly similar sorts but the implementations actually differ.

Posts in Channels

Post sorting in channels is the more straightforward version of post sorting, there are 3 kinds we use: Hot, New, Top

Posts in Frontpage

• Hot - posts are sorted using a normalized version of the hot algorithm. This is done to ensure that content from less active channels isn’t overshadowed by content from more popular channels.
  • See the corresponding code in the reddit source:
    • https://github.com/mitodl/reddit/blob/stable/r2/r2/lib/normalized_hot.py#L38-L79
• New and Top - same method as channels

#### Comments

Comments only have a few sorting options we’re currently using: New, Old, and Confidence