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Explain When To Use Field Grouping In Storm? Is There Any Time-out Or Limit To Known Field Values? |
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Answer» Field grouping in storm uses a mod HASH function to decide which task to SEND a TUPLE, ensuring which task will be processed in the correct order. For that, you don’t require any cache. So, there is no time-out or limit to KNOWN field values. The stream is partitioned by the fields specified in the grouping. For EXAMPLE, if the stream is grouped by the “user-id” field, tuples with the same “user-id” will always go to the same task, but tuples with different “user-id”‘s may go to different tasks. Field grouping in storm uses a mod hash function to decide which task to send a tuple, ensuring which task will be processed in the correct order. For that, you don’t require any cache. So, there is no time-out or limit to known field values. The stream is partitioned by the fields specified in the grouping. For example, if the stream is grouped by the “user-id” field, tuples with the same “user-id” will always go to the same task, but tuples with different “user-id”‘s may go to different tasks. |
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