If you're intending to partition database tables across servers (aka "shard") by users: 1. Make sure every table has a user_id field 2. Make sure every reco

If you're intending to partition database tables across servers (aka "shard") by users: 1. Make sure every table has a user_id field 2. Make sure every record gets that field populated 3. Don't forget to index it Watch out for queries that don't use the field as part of their 'where' clause.