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Table Of Contents
NoSQL Data Models
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We must recall that, in the Pub/Sub context, queries (subscriptions) are stored to be evaluated on-the-fly. Therefore, all the optimization is done in such a way as to process millions of queries on incoming items. One of the main techniques is to factorize treatments since there is a high probability that queries share the same operations.
In this section, we present our solution to quickly filter out items based on novelty and diversity criteria. It also allows us to efficiently store and manage items’ histories for all subscriptions.
Since an item can belong to several histories, we need to avoid keeping all items. A simple solution consists in storing the last N notified items [ZHA 02] for each subscription and in factorizing histories by storing each item only once. However, the publication rate strongly differs from one source to another and this approach will impact...
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