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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.ql.ppd;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.Operator;
import org.apache.hadoop.hive.ql.lib.NodeProcessorCtx;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
import org.apache.hadoop.hive.ql.plan.OperatorDesc;
/**
* Context for Expression Walker for determining predicate pushdown candidates
* It contains a ExprInfo object for each expression that is processed.
*/
public class ExprWalkerInfo implements NodeProcessorCtx {
/** Information maintained for an expr while walking an expr tree. */
private static class ExprInfo {
/**
* true if expr rooted at this node doesn't contain more than one table.
* alias
*/
public boolean isCandidate = false;
/** alias that this expression refers to. */
public String alias = null;
/** new expr for this expression. */
public ExprNodeDesc convertedExpr = null;
public ExprInfo() {
}
public ExprInfo(boolean isCandidate, String alias, ExprNodeDesc replacedNode) {
this.isCandidate = isCandidate;
this.alias = alias;
convertedExpr = replacedNode;
}
}
protected static final Log LOG = LogFactory.getLog(OpProcFactory.class
.getName());;
private Operator op = null;
/**
* Values the expression sub-trees (predicates) that can be pushed down for
* root expression tree. Since there can be more than one alias in an
* expression tree, this is a map from the alias to predicates.
*/
private final Map> pushdownPreds;
/**
* Values the expression sub-trees (predicates) that can not be pushed down for
* root expression tree. Since there can be more than one alias in an
* expression tree, this is a map from the alias to predicates.
*/
private final Map> nonFinalPreds;
/**
* this map contains a expr infos. Each key is a node in the expression tree
* and the information for each node is the value which is used while walking
* the tree by its parent.
*/
private final Map exprInfoMap;
/**
* This is a map from a new pushdown expressions generated by the ExprWalker
* to the old pushdown expression that it originated from. For example, if
* an output column of the current operator is _col0, which comes from an
* input column _col1, this would map the filter "Column[_col1]=2" to
* "Column[_col0]=2" ("Column[_col1]=2" is new because we move from children
* operators to parents in PPD)
*/
private final Map newToOldExprMap;
private boolean isDeterministic = true;
public ExprWalkerInfo() {
pushdownPreds = new HashMap>();
nonFinalPreds = new HashMap>();
exprInfoMap = new HashMap();
newToOldExprMap = new HashMap();
}
public ExprWalkerInfo(Operator op) {
this.op = op;
pushdownPreds = new HashMap>();
exprInfoMap = new HashMap();
nonFinalPreds = new HashMap>();
newToOldExprMap = new HashMap();
}
/**
* @return the op of this expression.
*/
public Operator getOp() {
return op;
}
/**
* @return the new expression to old expression map
*/
public Map getNewToOldExprMap() {
return newToOldExprMap;
}
/**
* @return converted expression for give node. If there is none then returns
* null.
*/
public ExprNodeDesc getConvertedNode(ExprNodeDesc nd) {
ExprInfo ei = exprInfoMap.get(nd);
if (ei == null) {
return null;
}
return ei.convertedExpr;
}
/**
* adds a replacement node for this expression.
*
* @param oldNode
* original node
* @param newNode
* new node
*/
public void addConvertedNode(ExprNodeDesc oldNode, ExprNodeDesc newNode) {
ExprInfo ei = exprInfoMap.get(oldNode);
if (ei == null) {
ei = new ExprInfo();
exprInfoMap.put(oldNode, ei);
}
ei.convertedExpr = newNode;
exprInfoMap.put(newNode, new ExprInfo(ei.isCandidate, ei.alias, null));
}
/**
* Returns true if the specified expression is pushdown candidate else false.
*
* @param expr
* @return true or false
*/
public boolean isCandidate(ExprNodeDesc expr) {
ExprInfo ei = exprInfoMap.get(expr);
if (ei == null) {
return false;
}
return ei.isCandidate;
}
/**
* Marks the specified expr to the specified value.
*
* @param expr
* @param b
* can
*/
public void setIsCandidate(ExprNodeDesc expr, boolean b) {
ExprInfo ei = exprInfoMap.get(expr);
if (ei == null) {
ei = new ExprInfo();
exprInfoMap.put(expr, ei);
}
ei.isCandidate = b;
}
/**
* Returns the alias of the specified expr.
*
* @param expr
* @return The alias of the expression
*/
public String getAlias(ExprNodeDesc expr) {
ExprInfo ei = exprInfoMap.get(expr);
if (ei == null) {
return null;
}
return ei.alias;
}
/**
* Adds the specified alias to the specified expr.
*
* @param expr
* @param alias
*/
public void addAlias(ExprNodeDesc expr, String alias) {
if (alias == null) {
return;
}
ExprInfo ei = exprInfoMap.get(expr);
if (ei == null) {
ei = new ExprInfo();
exprInfoMap.put(expr, ei);
}
ei.alias = alias;
}
/**
* Adds the specified expr as the top-most pushdown expr (ie all its children
* can be pushed).
*
* @param expr
*/
public void addFinalCandidate(ExprNodeDesc expr) {
addFinalCandidate(getAlias(expr), expr);
}
public void addFinalCandidate(String alias, ExprNodeDesc expr) {
getPushdownPreds(alias).add(expr);
}
/**
* Adds the passed list of pushDowns for the alias.
*
* @param alias
* @param pushDowns
*/
public void addPushDowns(String alias, List pushDowns) {
getPushdownPreds(alias).addAll(pushDowns);
}
/**
* Returns the list of pushdown expressions for each alias that appear in the
* current operator's RowResolver. The exprs in each list can be combined
* using conjunction (AND).
*
* @return the map of alias to a list of pushdown predicates
*/
public Map> getFinalCandidates() {
return pushdownPreds;
}
private List getPushdownPreds(String alias) {
List predicates = pushdownPreds.get(alias);
if (predicates == null) {
pushdownPreds.put(alias, predicates = new ArrayList());
}
return predicates;
}
public boolean hasAnyCandidates() {
if (pushdownPreds == null || pushdownPreds.isEmpty()) {
return false;
}
for (List exprs : pushdownPreds.values()) {
if (!exprs.isEmpty()) {
return true;
}
}
return false;
}
/**
* Adds the specified expr as a non-final candidate
*
* @param expr
*/
public void addNonFinalCandidate(ExprNodeDesc expr) {
String alias = getAlias(expr);
if (nonFinalPreds.get(alias) == null) {
nonFinalPreds.put(alias, new ArrayList());
}
nonFinalPreds.get(alias).add(expr);
}
/**
* Returns list of non-final candidate predicate for each map.
*
* @return list of non-final candidate predicates
*/
public Map> getNonFinalCandidates() {
return nonFinalPreds;
}
public Map> getResidualPredicates(boolean clear) {
Map> oldExprs = new HashMap>();
for (Map.Entry> entry : nonFinalPreds.entrySet()) {
List converted = new ArrayList();
for (ExprNodeDesc newExpr : entry.getValue()) {
converted.add(newToOldExprMap.get(newExpr));
}
oldExprs.put(entry.getKey(), converted);
}
if (clear) {
nonFinalPreds.clear();
}
return oldExprs;
}
/**
* Merges the specified pushdown predicates with the current class.
*
* @param ewi
* ExpressionWalkerInfo
*/
public void merge(ExprWalkerInfo ewi) {
if (ewi == null) {
return;
}
for (Entry> e : ewi.getFinalCandidates()
.entrySet()) {
List predList = pushdownPreds.get(e.getKey());
if (predList != null) {
predList.addAll(e.getValue());
} else {
pushdownPreds.put(e.getKey(), e.getValue());
}
}
for (Entry> e : ewi.getNonFinalCandidates()
.entrySet()) {
List predList = nonFinalPreds.get(e.getKey());
if (predList != null) {
predList.addAll(e.getValue());
} else {
nonFinalPreds.put(e.getKey(), e.getValue());
}
}
newToOldExprMap.putAll(ewi.getNewToOldExprMap());
}
/**
* sets the deterministic flag for this expression.
*
* @param b
* deterministic or not
*/
public void setDeterministic(boolean b) {
isDeterministic = b;
}
/**
* @return whether this expression is deterministic or not.
*/
public boolean isDeterministic() {
return isDeterministic;
}
}
