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by MichaelGG
4077 days ago
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Pick a good shard key. In the case of a per-page-per-user ratings system, if you shard on the PageId, then you can locally check consistency to make sure there's no duplicate (PageId, UserId) keys. You can check the same if you shard on UserId, but then doing aggregates can be more difficult since you need to talk to every shard to find out a page's rating. |
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