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Besides the replication of a complete query, the user can decide to replicate just a subset of the operators. Listing 2 shows the query definition in PQL. It's the same query as in Listing 1 with the exception that the replication mechanism has an additional argument. That argument defines the start and end point of the replication (the replication will begin after the start and end before the end). Values for start and end can either be a source name (e.g., nexmark:bid; only allowed for start) or a unique ID of an operator.
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