LDS Performance Improvements

[richardjrossiii]

This is a master issue for all things related to local datastore performance improvements.

• [x] Make LDS stop checkpointing and making copies of objects for mutable containers (#102)
• [ ] Make LDS query matching more efficient by not loading every object into memory for a specified pin.
• [ ] Make LDS use PFObjectState and PFUserState instead of PFObject and PFUser, to reduce the amount of locking required for every LDS operation.
• [ ] Improve LDS PFRelation tracking.
• [ ] Update LDS database schema to allow for query matching in the database layer itself.

For anyone reaching this issue as a result of currently bad LDS performance here's our current recommendations:

• Keep your object schemas as small as possible - the faster it is to parse them from JSON, the better.
• Relations are currently inefficient. If you can avoid them, do so.
• Minimize usage of any values of the following classes:
  • NSArray
  • NSDictionary
  • PFACL
  • PFGeoPoint
• Whenever possible, use smaller pins. Because LDS loads all objects in a single pin before evaluating a query, the smaller the pin is, the better.

[stale[bot]]

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