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No public interfaces will be impacted. We will introduce the config SELF_JOIN_OPTIMIZATION_CONFIG that enables/disables the optimization. It will only take effect if the config TOPOLOGY_OPTIMIZATION_CONFIG is enabledThe config TOPOLOGY_OPTIMIZATION_CONFIG will be extended to accept a list of optimization rule configs in addition to the global values "all" and "none" .

Proposed Changes

The changes required to implement this proposal are:

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The algorithm to identify whether two streams represent the same entity will check that :

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the

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StreamSourceNode node has a single parent

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If all these conditions hold, then the join can be optimized as a self join. 

• Implement the self-join operator 

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