Tim Armstrong has posted comments on this change. ( http://gerrit.cloudera.org:8080/14129 )
Change subject: IMPALA-8819: BufferedPlanRootSink should handle non-default fetch sizes ...................................................................... Patch Set 2: (1 comment) http://gerrit.cloudera.org:8080/#/c/14129/2/be/src/exec/buffered-plan-root-sink.cc File be/src/exec/buffered-plan-root-sink.cc: http://gerrit.cloudera.org:8080/#/c/14129/2/be/src/exec/buffered-plan-root-sink.cc@143 PS2, Line 143: // If 'num_results' <= 0 then by default fetch BATCH_SIZE rows. > I think it might be better to return > 1024 rows at a time by default - e.g Another thought about the batch sizes... The reason for the 1024 row internal batch size was so that RowBatches would fit in L1 cache (or close to it), while also being large enough to amortise fixed overhead of query execution. I think the calculation for returning rows to the client is a bit different - the network overheads for an RPC are pretty high so we care a lot about amortising that. -- To view, visit http://gerrit.cloudera.org:8080/14129 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I8dd4b397ab6457a4f85e635f239b2c67130fcce4 Gerrit-Change-Number: 14129 Gerrit-PatchSet: 2 Gerrit-Owner: Sahil Takiar <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Michael Ho <[email protected]> Gerrit-Reviewer: Sahil Takiar <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Comment-Date: Fri, 23 Aug 2019 17:34:34 +0000 Gerrit-HasComments: Yes
