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1. In most query engines 20 way joins and beyond is hard to reorder. So i would imagine that we would need a similar flag(hive.cbo.max.joins.supported) to control the length of join graph that is being considered for reordering. 2. Its reasonable to introduce ql.optimizer.CostBasedOptimizer which then calls in to Optiq based Optimizer. One thing to keep in mind, Optiq based optimizer would have both rule based and cost based portions. - John Pullokkaran On Feb. 17, 2014, 6:49 a.m., Harish Butani wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/18172/ > ----------------------------------------------------------- > > (Updated Feb. 17, 2014, 6:49 a.m.) > > > Review request for hive. > > > Bugs: HIVE-6439 > https://issues.apache.org/jira/browse/HIVE-6439 > > > Repository: hive-git > > > Description > ------- > > This patch introduces CBO step in SemanticAnalyzer. For now the > CostBasedOptimizer is an empty shell. > The contract between SemAly and CBO is: > CBO step is controlled by the 'hive.enable.cbo.flag'. > When true Hive SemAly will hand CBO a Hive Operator tree (with operators > annotated with stats). If it can CBO will return a better plan in Hive AST > form. > > > Diffs > ----- > > common/src/java/org/apache/hadoop/hive/conf/HiveConf.java a182cd7 > conf/hive-default.xml.template 0d08aa2 > ql/src/java/org/apache/hadoop/hive/ql/QueryProperties.java 1ba5654 > ql/src/java/org/apache/hadoop/hive/ql/optimizer/PreCBOOptimizer.java > PRE-CREATION > > ql/src/java/org/apache/hadoop/hive/ql/optimizer/optiq/CostBasedOptimizer.java > PRE-CREATION > ql/src/java/org/apache/hadoop/hive/ql/parse/ParseDriver.java 52c39c0 > ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java 77388dd > > Diff: https://reviews.apache.org/r/18172/diff/ > > > Testing > ------- > > > Thanks, > > Harish Butani > >
