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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.parse;
import org.antlr.runtime.TokenRewriteStream;
import org.apache.hadoop.hive.ql.Context;
/*
* Contains functionality that helps with understanding how a SubQuery was rewritten.
*/
public class SubQueryDiagnostic {
static QBSubQueryRewrite getRewrite(QBSubQuery subQuery,
TokenRewriteStream stream,
Context ctx) {
if (ctx.getExplain()) {
return new QBSubQueryRewrite(subQuery, stream);
} else {
return new QBSubQueryRewriteNoop(subQuery, stream);
}
}
/*
* Responsible for capturing SubQuery rewrites and providing the rewritten query
* as SQL.
*/
public static class QBSubQueryRewrite {
QBSubQuery subQuery;
TokenRewriteStream stream;
/*
* the rewritten where Clause
*/
String whereClause;
/*
* any additions to the SubQueries Select Clause.
*/
String selectClauseAdditions;
/*
* additions to the Group By Clause.
*/
String gByClauseAdditions;
boolean addGroupByClause;
String joiningCondition;
String outerQueryPostJoinCond;
QBSubQueryRewrite(QBSubQuery subQuery,
TokenRewriteStream stream) {
this.subQuery = subQuery;
this.stream = stream;
}
public String getRewrittenQuery() {
ASTNode sqAST = subQuery.getSubQueryAST();
if (whereClause != null) {
ASTNode whereAST = (ASTNode) sqAST.getChild(1).getChild(2);
stream.replace(subQuery.getAlias(),
whereAST.getTokenStartIndex(),
whereAST.getTokenStopIndex(),
whereClause);
}
if (selectClauseAdditions != null) {
ASTNode selectClause = (ASTNode) sqAST.getChild(1).getChild(1);
stream.insertAfter(subQuery.getAlias(),
selectClause.getTokenStopIndex(), selectClauseAdditions);
}
if (gByClauseAdditions != null) {
if (!addGroupByClause) {
ASTNode groupBy = (ASTNode) sqAST.getChild(1).getChild(3);
stream.insertAfter(subQuery.getAlias(),
groupBy.getTokenStopIndex(), gByClauseAdditions);
}
else {
gByClauseAdditions = " group by " + gByClauseAdditions;
stream.insertAfter(subQuery.getAlias(),
sqAST.getTokenStopIndex() - 1, gByClauseAdditions);
}
}
try {
return
stream.toString(subQuery.getAlias(),
sqAST.getTokenStartIndex(),
sqAST.getTokenStopIndex())
+ " " + subQuery.getAlias();
} finally {
stream.deleteProgram(subQuery.getAlias());
}
}
public String getJoiningCondition() {
return joiningCondition;
}
void addWhereClauseRewrite(ASTNode predicate) {
String cond = stream.toString(predicate.getTokenStartIndex(), predicate.getTokenStopIndex());
addWhereClauseRewrite(cond);
}
void addWhereClauseRewrite(String cond) {
whereClause = whereClause == null ? "where " : whereClause + " and ";
whereClause += cond;
}
void addSelectClauseRewrite(ASTNode selectExpr, String alias) {
if ( selectClauseAdditions == null ) {
selectClauseAdditions = "";
}
selectClauseAdditions += ", " +
stream.toString(selectExpr.getTokenStartIndex(), selectExpr.getTokenStopIndex()) +
" as " + alias;
}
void setAddGroupByClause() {
this.addGroupByClause = true;
}
void addGByClauseRewrite(ASTNode selectExpr) {
if ( gByClauseAdditions == null ) {
gByClauseAdditions = "";
}
if ( !addGroupByClause || !gByClauseAdditions.equals("") ) {
gByClauseAdditions += ", ";
}
gByClauseAdditions += stream.toString(
selectExpr.getTokenStartIndex(),
selectExpr.getTokenStopIndex());
}
/*
* joinCond represents a correlated predicate.
* leftIsRewritten, rightIsRewritten indicates if either side has been replaced by a column alias.
*
* If a side is not rewritten, we get its text from the tokenstream.
* For rewritten conditions we form the text based on the table and column reference.
*/
void addJoinCondition(ASTNode joinCond, boolean leftIsRewritten, boolean rightIsRewritten) {
StringBuilder b = new StringBuilder();
if ( joiningCondition == null ) {
joiningCondition = " on ";
} else {
b.append(" and ");
}
addCondition(b, (ASTNode) joinCond.getChild(0), leftIsRewritten);
b.append(" = ");
addCondition(b, (ASTNode) joinCond.getChild(1), rightIsRewritten);
joiningCondition += b.toString();
}
private void addCondition(StringBuilder b, ASTNode cond, boolean rewritten) {
if ( !rewritten ) {
b.append(stream.toString(cond.getTokenStartIndex(), cond.getTokenStopIndex()));
} else {
addReference(b, cond);
}
}
private void addReference(StringBuilder b, ASTNode ref) {
if ( ref.getType() == HiveParser.DOT ) {
b.append(ref.getChild(0).getChild(0).getText()).
append(".").
append(ref.getChild(1).getText());
} else {
b.append(ref.getText());
}
}
void addPostJoinCondition(ASTNode cond) {
StringBuilder b = new StringBuilder();
addReference(b, (ASTNode) cond.getChild(1));
outerQueryPostJoinCond = b.toString() + " is null";
}
public String getOuterQueryPostJoinCond() {
return outerQueryPostJoinCond;
}
}
/*
* In the non explain code path, we don't need to track Query rewrites.
* All add fns during Plan generation are Noops.
* If the get Rewrite methods are called, an UnsupportedOperationException is thrown.
*/
public static class QBSubQueryRewriteNoop extends QBSubQueryRewrite {
QBSubQueryRewriteNoop(QBSubQuery subQuery, TokenRewriteStream stream) {
super(subQuery, stream);
}
@Override
public final String getRewrittenQuery() {
throw new UnsupportedOperationException();
}
@Override
public final String getJoiningCondition() {
throw new UnsupportedOperationException();
}
@Override
final void addWhereClauseRewrite(ASTNode predicate) {
}
@Override
final void addWhereClauseRewrite(String cond) {
}
@Override
final void addSelectClauseRewrite(ASTNode selectExpr, String alias) {
}
@Override
final void setAddGroupByClause() {
}
@Override
final void addGByClauseRewrite(ASTNode selectExpr) {
}
@Override
final void addJoinCondition(ASTNode joinCond, boolean leftIsRewritten,
boolean rightIsRewritten) {
}
@Override
final void addPostJoinCondition(ASTNode cond) {
}
@Override
public final String getOuterQueryPostJoinCond() {
throw new UnsupportedOperationException();
}
}
}
