Thomas Tauber-Marshall has uploaded this change for review. ( http://gerrit.cloudera.org:8080/10119
Change subject: IMPALA-6821: Push down limits into Kudu ...................................................................... IMPALA-6821: Push down limits into Kudu This patch takes advantage of a recent change in Kudu (KUDU-16) that exposes the ability to set limits on KuduScanners. Since each KuduScanner corresponds to a scan token, and there will be multiple scan tokens per query, this is just a performance optimization in cases where the limit is smaller than the number of rows per token, and Impala still needs to apply the limit on our side for cases where the limit is greater than the number of rows per token. Testing: - Updated test_limit to run against Kudu by moving the few test cases that Kudu cannot support to a different test. - For the query 'select * from tpch_kudu.lineitem limit 1', a best case perf scenario for this change where the limit is highly effective, the time spent in the Kudu scan node was reduced from 6.107ms to 3.498ms (avg over 3 runs). - For the query 'select count(*) from tpch_kudu.lineitem limit 1000000', a worst case perf scenario for this change where the limit is ineffective, the time spent in the Kudu scan node was essentially unchanged, 62.387ms previously vs. 64.168ms (avg over 3 runs). Change-Id: Ibe35e70065d8706b575e24fe20902cd405b49941 --- M be/src/exec/kudu-scanner.cc A testdata/workloads/functional-query/queries/QueryTest/limit-nondeterministic.test M testdata/workloads/functional-query/queries/QueryTest/limit.test M tests/query_test/test_queries.py 4 files changed, 87 insertions(+), 73 deletions(-) git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/19/10119/1 -- To view, visit http://gerrit.cloudera.org:8080/10119 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: newchange Gerrit-Change-Id: Ibe35e70065d8706b575e24fe20902cd405b49941 Gerrit-Change-Number: 10119 Gerrit-PatchSet: 1 Gerrit-Owner: Thomas Tauber-Marshall <tmarsh...@cloudera.com>
