liuyao has uploaded this change for review. (
http://gerrit.cloudera.org:8080/17821
Change subject: IMPALA-2581: LIMIT can be propagated down into some aggregations
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IMPALA-2581: LIMIT can be propagated down into some aggregations
This patch does two things:
1. In some cases, push down limit to pre-aggregation
a) aggregation node has no aggregate function
b) aggregation node has no predicate
2. finish aggregation when number of unique keys of hash table has
exceeded the limit.
Queries like
SELECT DISTINCT f FROM t LIMIT n
Can pass the LIMIT all the way down to the pre-aggregation, which
leads to a nearly unbounded speedup on these queries in large tables
when n is low.
Change-Id: I930a6cb203615acfc03f23118d1bc1f0ea360995
---
M be/src/exec/aggregation-node-base.cc
M be/src/exec/aggregation-node-base.h
M be/src/exec/aggregation-node.cc
M be/src/exec/aggregator.h
M be/src/exec/grouping-aggregator.cc
M be/src/exec/grouping-aggregator.h
M be/src/exec/non-grouping-aggregator.h
M be/src/exec/streaming-aggregation-node.cc
M fe/src/main/java/org/apache/impala/planner/DistributedPlanner.java
M testdata/cluster/node_templates/common/etc/hadoop/conf/hdfs-site.xml.tmpl
M
testdata/workloads/functional-planner/queries/PlannerTest/resource-requirements.test
M
testdata/workloads/functional-planner/queries/PlannerTest/setoperation-rewrite.test
M
testdata/workloads/functional-planner/queries/PlannerTest/subquery-rewrite.test
M testdata/workloads/functional-planner/queries/PlannerTest/tpcds/tpcds-q06.test
M testdata/workloads/functional-planner/queries/PlannerTest/tpcds/tpcds-q54.test
M testdata/workloads/functional-query/queries/QueryTest/spilling.test
M testdata/workloads/targeted-perf/queries/aggregation.test
17 files changed, 127 insertions(+), 24 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/21/17821/2
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I930a6cb203615acfc03f23118d1bc1f0ea360995
Gerrit-Change-Number: 17821
Gerrit-PatchSet: 2
Gerrit-Owner: liuyao <liu...@sensorsdata.cn>
