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A lot of times its because you want want a rollup table but also need to answer cardinality questions. So instead of scanning millions of rows you can have a si
by mrits 12y ago
A lot of times its because you want want a rollup table but also need to answer cardinality questions. So instead of scanning millions of rows you can have a single rolled up array that you can perform set operations on other rolls (instead of a numeric aggregate that does not have the appropriate mathematical properties to do much with).
- bonesmoses 12y agoWell... generally this is solved via indices. An event log indexed by user ID would have the same effect. You get all the user info, and if you really need to grab historical or event data, it's there when necessary for parts of the app that actually need it. I own a lot of stuff, but I don't drag my house everywhere in case I might need something. :p
- deleted 12y ago[deleted]