/**
* 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.index;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Stack;
import org.apache.hadoop.hive.ql.exec.FunctionRegistry;
import org.apache.hadoop.hive.ql.lib.DefaultGraphWalker;
import org.apache.hadoop.hive.ql.lib.DefaultRuleDispatcher;
import org.apache.hadoop.hive.ql.lib.Dispatcher;
import org.apache.hadoop.hive.ql.lib.GraphWalker;
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.lib.Rule;
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;
import org.apache.hadoop.hive.ql.plan.ExprNodeDescUtils;
import org.apache.hadoop.hive.ql.plan.ExprNodeFieldDesc;
import org.apache.hadoop.hive.ql.plan.ExprNodeGenericFuncDesc;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFBridge;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFToBinary;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFToChar;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFToDate;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFToDecimal;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFToUnixTimeStamp;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFToUtcTimestamp;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFToVarchar;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoFactory;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDFBaseCompare;
/**
* IndexPredicateAnalyzer decomposes predicates, separating the parts
* which can be satisfied by an index from the parts which cannot.
* Currently, it only supports pure conjunctions over binary expressions
* comparing a column reference with a constant value. It is assumed
* that all column aliases encountered refer to the same table.
*/
public class IndexPredicateAnalyzer {
private final Set<String> udfNames;
private final Map<String, Set<String>> columnToUDFs;
private FieldValidator fieldValidator;
private boolean acceptsFields;
public IndexPredicateAnalyzer() {
udfNames = new HashSet<String>();
columnToUDFs = new HashMap<String, Set<String>>();
}
public void setFieldValidator(FieldValidator fieldValidator) {
this.fieldValidator = fieldValidator;
}
/**
* Registers a comparison operator as one which can be satisfied
* by an index search. Unless this is called, analyzePredicate
* will never find any indexable conditions.
*
* @param udfName name of comparison operator as returned
* by either {@link GenericUDFBridge#getUdfName} (for simple UDF's)
* or udf.getClass().getName() (for generic UDF's).
*/
public void addComparisonOp(String udfName) {
udfNames.add(udfName);
}
/**
* Clears the set of column names allowed in comparisons. (Initially, all
* column names are allowed.)
*/
public void clearAllowedColumnNames() {
columnToUDFs.clear();
}
/**
* Adds a column name to the set of column names allowed.
*
* @param columnName name of column to be allowed
*/
public void allowColumnName(String columnName) {
columnToUDFs.put(columnName, udfNames);
}
/**
* add allowed functions per column
* @param columnName
* @param udfs
*/
public void addComparisonOp(String columnName, String... udfs) {
Set<String> allowed = columnToUDFs.get(columnName);
if (allowed == null || allowed == udfNames) {
// override
columnToUDFs.put(columnName, new HashSet<String>(Arrays.asList(udfs)));
} else {
allowed.addAll(Arrays.asList(udfs));
}
}
/**
* Analyzes a predicate.
*
* @param predicate predicate to be analyzed
*
* @param searchConditions receives conditions produced by analysis
*
* @return residual predicate which could not be translated to
* searchConditions
*/
public ExprNodeDesc analyzePredicate(
ExprNodeDesc predicate,
final List<IndexSearchCondition> searchConditions) {
Map<Rule, NodeProcessor> opRules = new LinkedHashMap<Rule, NodeProcessor>();
NodeProcessor nodeProcessor = new NodeProcessor() {
@Override
public Object process(Node nd, Stack<Node> stack,
NodeProcessorCtx procCtx, Object... nodeOutputs)
throws SemanticException {
// We can only push down stuff which appears as part of
// a pure conjunction: reject OR, CASE, etc.
for (Node ancestor : stack) {
if (nd == ancestor) {
break;
}
if (!FunctionRegistry.isOpAnd((ExprNodeDesc) ancestor)) {
return nd;
}
}
return analyzeExpr((ExprNodeGenericFuncDesc) nd, searchConditions, nodeOutputs);
}
};
Dispatcher disp = new DefaultRuleDispatcher(
nodeProcessor, opRules, null);
GraphWalker ogw = new DefaultGraphWalker(disp);
ArrayList<Node> topNodes = new ArrayList<Node>();
topNodes.add(predicate);
HashMap<Node, Object> nodeOutput = new HashMap<Node, Object>();
try {
ogw.startWalking(topNodes, nodeOutput);
} catch (SemanticException ex) {
throw new RuntimeException(ex);
}
ExprNodeDesc residualPredicate = (ExprNodeDesc) nodeOutput.get(predicate);
return residualPredicate;
}
//Check if ExprNodeColumnDesc is wrapped in expr.
//If so, peel off. Otherwise return itself.
private ExprNodeDesc getColumnExpr(ExprNodeDesc expr) {
if (expr instanceof ExprNodeColumnDesc) {
return expr;
}
ExprNodeGenericFuncDesc funcDesc = null;
if (expr instanceof ExprNodeGenericFuncDesc) {
funcDesc = (ExprNodeGenericFuncDesc) expr;
}
if (null == funcDesc) {
return expr;
}
GenericUDF udf = funcDesc.getGenericUDF();
// check if its a simple cast expression.
if ((udf instanceof GenericUDFBridge || udf instanceof GenericUDFToBinary
|| udf instanceof GenericUDFToChar || udf instanceof GenericUDFToVarchar
|| udf instanceof GenericUDFToDecimal || udf instanceof GenericUDFToDate
|| udf instanceof GenericUDFToUnixTimeStamp || udf instanceof GenericUDFToUtcTimestamp)
&& funcDesc.getChildren().size() == 1
&& funcDesc.getChildren().get(0) instanceof ExprNodeColumnDesc) {
return expr.getChildren().get(0);
}
return expr;
}
private ExprNodeDesc analyzeExpr(
ExprNodeGenericFuncDesc expr,
List<IndexSearchCondition> searchConditions,
Object... nodeOutputs) {
if (FunctionRegistry.isOpAnd(expr)) {
assert(nodeOutputs.length == 2);
ExprNodeDesc residual1 = (ExprNodeDesc) nodeOutputs[0];
ExprNodeDesc residual2 = (ExprNodeDesc) nodeOutputs[1];
if (residual1 == null) {
return residual2;
}
if (residual2 == null) {
return residual1;
}
List<ExprNodeDesc> residuals = new ArrayList<ExprNodeDesc>();
residuals.add(residual1);
residuals.add(residual2);
return new ExprNodeGenericFuncDesc(
TypeInfoFactory.booleanTypeInfo,
FunctionRegistry.getGenericUDFForAnd(),
residuals);
}
GenericUDF genericUDF = expr.getGenericUDF();
if (!(genericUDF instanceof GenericUDFBaseCompare)) {
return expr;
}
ExprNodeDesc expr1 = (ExprNodeDesc) nodeOutputs[0];
ExprNodeDesc expr2 = (ExprNodeDesc) nodeOutputs[1];
// We may need to peel off the GenericUDFBridge that is added by CBO or user
if (expr1.getTypeInfo().equals(expr2.getTypeInfo())) {
expr1 = getColumnExpr(expr1);
expr2 = getColumnExpr(expr2);
}
ExprNodeDesc[] extracted = ExprNodeDescUtils.extractComparePair(expr1, expr2);
if (extracted == null || (extracted.length > 2 && !acceptsFields)) {
return expr;
}
ExprNodeColumnDesc columnDesc;
ExprNodeConstantDesc constantDesc;
if (extracted[0] instanceof ExprNodeConstantDesc) {
genericUDF = genericUDF.flip();
columnDesc = (ExprNodeColumnDesc) extracted[1];
constantDesc = (ExprNodeConstantDesc) extracted[0];
} else {
columnDesc = (ExprNodeColumnDesc) extracted[0];
constantDesc = (ExprNodeConstantDesc) extracted[1];
}
Set<String> allowed = columnToUDFs.get(columnDesc.getColumn());
if (allowed == null) {
return expr;
}
String udfName = genericUDF.getUdfName();
if (!allowed.contains(genericUDF.getUdfName())) {
return expr;
}
String[] fields = null;
if (extracted.length > 2) {
ExprNodeFieldDesc fieldDesc = (ExprNodeFieldDesc) extracted[2];
if (!isValidField(fieldDesc)) {
return expr;
}
fields = ExprNodeDescUtils.extractFields(fieldDesc);
}
// We also need to update the expr so that the index query can be generated.
// Note that, hive does not support UDFToDouble etc in the query text.
List<ExprNodeDesc> list = new ArrayList<ExprNodeDesc>();
list.add(expr1);
list.add(expr2);
expr = new ExprNodeGenericFuncDesc(expr.getTypeInfo(), expr.getGenericUDF(), list);
searchConditions.add(
new IndexSearchCondition(
columnDesc,
udfName,
constantDesc,
expr,
fields));
// we converted the expression to a search condition, so
// remove it from the residual predicate
return fields == null ? null : expr;
}
private boolean isValidField(ExprNodeFieldDesc field) {
return fieldValidator == null || fieldValidator.validate(field);
}
/**
* Translates search conditions back to ExprNodeDesc form (as
* a left-deep conjunction).
*
* @param searchConditions (typically produced by analyzePredicate)
*
* @return ExprNodeGenericFuncDesc form of search conditions
*/
public ExprNodeGenericFuncDesc translateSearchConditions(
List<IndexSearchCondition> searchConditions) {
ExprNodeGenericFuncDesc expr = null;
for (IndexSearchCondition searchCondition : searchConditions) {
if (expr == null) {
expr = searchCondition.getComparisonExpr();
continue;
}
List<ExprNodeDesc> children = new ArrayList<ExprNodeDesc>();
children.add(expr);
children.add(searchCondition.getComparisonExpr());
expr = new ExprNodeGenericFuncDesc(
TypeInfoFactory.booleanTypeInfo,
FunctionRegistry.getGenericUDFForAnd(),
children);
}
return expr;
}
public void setAcceptsFields(boolean acceptsFields) {
this.acceptsFields = acceptsFields;
}
public static interface FieldValidator {
boolean validate(ExprNodeFieldDesc exprNodeDesc);
}
public static IndexPredicateAnalyzer createAnalyzer(boolean equalOnly) {
IndexPredicateAnalyzer analyzer = new IndexPredicateAnalyzer();
analyzer.addComparisonOp("org.apache.hadoop.hive.ql.udf.generic.GenericUDFOPEqual");
if (equalOnly) {
return analyzer;
}
analyzer.addComparisonOp("org.apache.hadoop.hive.ql.udf.generic.GenericUDFOPEqualOrGreaterThan");
analyzer.addComparisonOp("org.apache.hadoop.hive.ql.udf.generic.GenericUDFOPEqualOrLessThan");
analyzer.addComparisonOp("org.apache.hadoop.hive.ql.udf.generic.GenericUDFOPLessThan");
analyzer.addComparisonOp("org.apache.hadoop.hive.ql.udf.generic.GenericUDFOPGreaterThan");
return analyzer;
}
}