Joe McDonnell has posted comments on this change. ( http://gerrit.cloudera.org:8080/15497 )
Change subject: IMPALA-8005: Randomize partitioning exchanges. ...................................................................... Patch Set 3: (1 comment) http://gerrit.cloudera.org:8080/#/c/15497/3/be/src/runtime/data-stream-test.cc File be/src/runtime/data-stream-test.cc: http://gerrit.cloudera.org:8080/#/c/15497/3/be/src/runtime/data-stream-test.cc@742 PS3, Line 742: if (map_query_1[i] != map_query_2[i]) { > It depends on what the core purpose of the test is. I am wondering if it i If I'm understanding this correctly, I think the probability of a false match should be very small. The odds of a value being hashed to the same receiver for both query1 and query2 is roughly 1/#receivers = 1/4. A false positive for this test would require all the values on all the receivers to be the same from query1 to query2. So, the probability of a false match is (1/4)^(#distinct values). It looks like the Sender uses a distinct value for each send, so there should be about 1024 distinct values (we should double check that). (1/4)^1024 is very small. Doing the check on the sender side would also work. I like the end-to-end aspect of this, but a direct comparison on the sender side would also be ok. -- To view, visit http://gerrit.cloudera.org:8080/15497 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I1936e6cc3e8d66420a5a9301f49221ca38f3e468 Gerrit-Change-Number: 15497 Gerrit-PatchSet: 3 Gerrit-Owner: Anurag Mantripragada <[email protected]> Gerrit-Reviewer: Aman Sinha <[email protected]> Gerrit-Reviewer: Anurag Mantripragada <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Joe McDonnell <[email protected]> Gerrit-Comment-Date: Wed, 25 Mar 2020 19:57:39 +0000 Gerrit-HasComments: Yes
