Examples of org.eigenbase.relopt.RelOptCost

org.eigenbase.relopt.RelOptCost
RelOptCost defines an interface for optimizer cost in terms of number of rows processed, CPU cost, and I/O cost. Optimizer implementations may use all of this information, or selectively ignore portions of it. The specific units for all of these quantities are rather vague; most relational expressions provide a default cost calculation, but optimizers can override this by plugging in their own cost models with well-defined meanings for each unit. Optimizers which supply their own cost models may also extend this interface with additional cost metrics such as memory usage.


  /*
   * Favor Broad Plans over Deep Plans.
   */
  public RelOptCost getCumulativeCost(HiveJoinRel rel) {
    RelOptCost cost = RelMetadataQuery.getNonCumulativeCost(rel);
    List<RelNode> inputs = rel.getInputs();
    RelOptCost maxICost = HiveCost.ZERO;
    for (RelNode input : inputs) {
      RelOptCost iCost = RelMetadataQuery.getCumulativeCost(input);
      if (maxICost.isLt(iCost)) {
        maxICost = iCost;
      }
    }
    return cost.plus(maxICost);

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    }


  @Override
  public RelOptCost computeSelfCost( RelOptPlanner planner )
    {
    final RelOptCost cost = super.computeSelfCost( planner );


    if( leftKeys.size() == 0 ) // cartesian product. make artificially expensive.
      return cost.multiplyBy( 10d );


    return cost.multiplyBy( .1 );
    }

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Related Classes of org.eigenbase.relopt.RelOptCost

cascading.lingual.optiq.CascadingJoinRel

org.apache.hadoop.hive.ql.optimizer.optiq.stats.HiveRelMdDistinctRowCount

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