wangsheng has uploaded a new patch set (#14). ( http://gerrit.cloudera.org:8080/18023 )
Change subject: IMPALA-7942 (part 2): Add query hints for predicate selectivities ...................................................................... IMPALA-7942 (part 2): Add query hints for predicate selectivities Currently, Impala only uses simple estimation to compute selectivity for some predicates, and this may lead to worse query plan due to CBO. Hence, we add new hints to reduce such errors. Maybe in the future, we can use histograms to get more precise query plan. This patch adds another query hints: 'SELECTIVITY', we can use this hint to original selectivity computing. Format like this: select col from t where (a=1) /* +SELECTIVITY(0.5) */; Besides, this hint is also valid for compound predicate like this: select col from t where (a=1 and b=2) /* +SELECTIVITY(0.5) */; But pay attention, if we want to use 'SELECTIVITY' hint for predicate, we need to wrap the predicate by braket, even for single binary predicate. Testing: - Added new fe tests in 'PlannerTest' - Added new fe tests in 'AnalyzeStmtsTest' for negative cases Change-Id: I2776b9bbd878b8a21d9c866b400140a454f59e1b --- M fe/src/main/cup/sql-parser.cup M fe/src/main/java/org/apache/impala/analysis/BinaryPredicate.java M fe/src/main/java/org/apache/impala/analysis/CompoundPredicate.java M fe/src/main/java/org/apache/impala/analysis/Expr.java M fe/src/main/java/org/apache/impala/analysis/InPredicate.java M fe/src/main/java/org/apache/impala/analysis/IsNullPredicate.java M fe/src/main/java/org/apache/impala/analysis/Predicate.java M fe/src/main/java/org/apache/impala/rewrite/BetweenToCompoundRule.java M fe/src/main/jflex/sql-scanner.flex M fe/src/test/java/org/apache/impala/analysis/AnalyzeStmtsTest.java M fe/src/test/java/org/apache/impala/planner/PlannerTest.java A testdata/workloads/functional-planner/queries/PlannerTest/predicate-selectivity-hint.test 12 files changed, 385 insertions(+), 5 deletions(-) git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/23/18023/14 -- To view, visit http://gerrit.cloudera.org:8080/18023 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: newpatchset Gerrit-Change-Id: I2776b9bbd878b8a21d9c866b400140a454f59e1b Gerrit-Change-Number: 18023 Gerrit-PatchSet: 14 Gerrit-Owner: wangsheng <sky...@163.com> Gerrit-Reviewer: Amogh Margoor <amarg...@gmail.com> Gerrit-Reviewer: Fucun Chu <chufu...@hotmail.com> Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com> Gerrit-Reviewer: Qifan Chen <qfc...@hotmail.com> Gerrit-Reviewer: Quanlong Huang <huangquanl...@gmail.com> Gerrit-Reviewer: Zoltan Borok-Nagy <borokna...@cloudera.com> Gerrit-Reviewer: wangsheng <sky...@163.com>
