Examples of org.apache.hadoop.hive.ql.optimizer.ConstantPropagate

org.apache.hadoop.hive.ql.optimizer.ConstantPropagate

Implementation of one of the rule-based optimization steps. ConstantPropagate traverse the DAG from root to child. For each conditional expression, process as follows: 1. Fold constant expression: if the expression is a UDF and all parameters are constant. 2. Shortcut expression: if the expression is a logical operator and it can be shortcut by some constants of its parameters. 3. Propagate expression: if the expression is an assignment like column=constant, the expression will be propagate to parents to see if further folding operation is possible.

    ogw.startWalking(topNodes, null);


    // need a new run of the constant folding because we might have created lots
    // of "and true and true" conditions.
    if(procCtx.conf.getBoolVar(ConfVars.HIVEOPTCONSTANTPROPAGATION)) {
      new ConstantPropagate().transform(procCtx.parseContext);
    }
  }

Examples of org.apache.hadoop.hive.ql.optimizer.ConstantPropagate

Related Classes of org.apache.hadoop.hive.ql.optimizer.ConstantPropagate