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The strategies are explained in the next sections. Partition and Allocation allow only one selected strategy. The other phases can be used multiple times per query. If the user had not specified strategies for some phases, OdysseusNet will use specific strategies as default (configurable):
| Phase | Default strategy |
|---|---|
| Preprocess | <none> |
| Partition | querycloud |
| Modification | <none> |
| Allocation | querycount |
| Postprocess | merge |
...
| Strategy name | Description |
|---|---|
localsink | Logical sink operators are staying local (on the distributing node) overriding allocation. Useful if the user wants to have the last operator to check the data stream results. |
localsource | Logical source operators are staying local (on the distribution node) overriding allocation. Useful if the user do not want to share its source operators to other nodes. |
merge | Two adjacent query parts which are assigned to the same node are merged to omit unneeded network-transmission operators. |
| discardedreplicates | Post processor to insert a sender for each {@link ReplicationMergeAO}. The sender will be inserted for the output port 1 that is not used normally. All discarded replicates are sent to port 1. The sender writes the data in a CSV file (one file per merger). The only argument for this post processor is the path to the CSV files. The names of the files are determined by the {@link ReplicationMergeAO} (name and hashCode). Used sender settings: |
| CalcLatency | Inserts a CalcLatencyAO before every real sink. Note that the sources must provide the meta attribute LatencyILatency metadata will be added to the sources automatically. This postprocessor needs the feature "Calculation Postprocessor Feature". |
| CalcDatarate | Inserts a DatarateAO after every source. Note that the IDatarate metadata will be added to the sources automatically. This postprocessor needs the feature "Calculation Postprocessor Feature". |