org.apache.hadoop.hive.ql.optimizer.listbucketingpruner.LBExprProcFactory Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
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package org.apache.hadoop.hive.ql.optimizer.listbucketingpruner;
import java.util.Map;
import org.apache.hadoop.hive.ql.lib.Node;
import org.apache.hadoop.hive.ql.lib.NodeProcessor;
import org.apache.hadoop.hive.ql.lib.NodeProcessorCtx;
import org.apache.hadoop.hive.ql.metadata.Partition;
import org.apache.hadoop.hive.ql.optimizer.PrunerExpressionOperatorFactory;
import org.apache.hadoop.hive.ql.optimizer.PrunerUtils;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.plan.ExprNodeColumnDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeConstantDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
/**
* Expression processor factory for list bucketing pruning. Each processor tries to
* convert the expression subtree into a list bucketing pruning expression. This
* expression is then used to figure out which skewed value to be used
*/
public class LBExprProcFactory extends PrunerExpressionOperatorFactory {
private LBExprProcFactory() {
// prevent instantiation
}
/**
* Processor for lbpr column expressions.
*/
public static class LBPRColumnExprProcessor extends ColumnExprProcessor {
@Override
protected ExprNodeDesc processColumnDesc(NodeProcessorCtx procCtx, ExprNodeColumnDesc cd) {
ExprNodeDesc newcd;
LBExprProcCtx ctx = (LBExprProcCtx) procCtx;
Partition part = ctx.getPart();
if (cd.getTabAlias().equalsIgnoreCase(ctx.getTabAlias())
&& isPruneForListBucketing(part, cd.getColumn())) {
newcd = cd.clone();
} else {
newcd = new ExprNodeConstantDesc(cd.getTypeInfo(), null);
}
return newcd;
}
/**
* Check if we prune it for list bucketing
* 1. column name is part of skewed column
* 2. partition has skewed value to location map
* @param part
* @param columnName
* @return
*/
private boolean isPruneForListBucketing(Partition part, String columnName) {
return ListBucketingPrunerUtils.isListBucketingPart(part)
&& (part.getSkewedColNames().contains(columnName));
}
}
/**
* Generates the list bucketing pruner for the expression tree.
*
* @param tabAlias
* The table alias of the partition table that is being considered
* for pruning
* @param pred
* The predicate from which the list bucketing pruner needs to be
* generated
* @param part
* The partition this walker is walking
* @throws SemanticException
*/
public static ExprNodeDesc genPruner(String tabAlias, ExprNodeDesc pred, Partition part)
throws SemanticException {
// Create the walker, the rules dispatcher and the context.
NodeProcessorCtx lbprCtx = new LBExprProcCtx(tabAlias, part);
Map outputMap = PrunerUtils.walkExprTree(pred, lbprCtx, getColumnProcessor(),
getFieldProcessor(), getGenericFuncProcessor(), getDefaultExprProcessor());
// Get the exprNodeDesc corresponding to the first start node;
return (ExprNodeDesc) outputMap.get(pred);
}
/**
* Instantiate column processor.
*
* @return
*/
public static NodeProcessor getColumnProcessor() {
return new LBPRColumnExprProcessor();
}
}