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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.plan;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.ql.exec.Task;
import org.apache.hadoop.hive.ql.exec.Utilities;
/**
* ConditionalResolverSkewJoin.
*
*/
public class ConditionalResolverCommonJoin implements ConditionalResolver, Serializable {
private static final long serialVersionUID = 1L;
private static final Logger LOG = LoggerFactory.getLogger(ConditionalResolverCommonJoin.class);
/**
* ConditionalResolverSkewJoinCtx.
*
*/
public static class ConditionalResolverCommonJoinCtx implements Serializable {
private static final long serialVersionUID = 1L;
private HashMap, Set> taskToAliases;
HashMap> pathToAliases;
HashMap aliasToKnownSize;
private Task commonJoinTask;
private Path localTmpDir;
private Path hdfsTmpDir;
public ConditionalResolverCommonJoinCtx() {
}
public HashMap, Set> getTaskToAliases() {
return taskToAliases;
}
public void setTaskToAliases(HashMap, Set> taskToAliases) {
this.taskToAliases = taskToAliases;
}
public Task getCommonJoinTask() {
return commonJoinTask;
}
public void setCommonJoinTask(Task commonJoinTask) {
this.commonJoinTask = commonJoinTask;
}
public HashMap getAliasToKnownSize() {
return aliasToKnownSize == null ?
aliasToKnownSize = new HashMap() : aliasToKnownSize;
}
public void setAliasToKnownSize(HashMap aliasToKnownSize) {
this.aliasToKnownSize = aliasToKnownSize;
}
public HashMap> getPathToAliases() {
return pathToAliases;
}
public void setPathToAliases(HashMap> pathToAliases) {
this.pathToAliases = pathToAliases;
}
public Path getLocalTmpDir() {
return localTmpDir;
}
public void setLocalTmpDir(Path localTmpDir) {
this.localTmpDir = localTmpDir;
}
public Path getHdfsTmpDir() {
return hdfsTmpDir;
}
public void setHdfsTmpDir(Path hdfsTmpDir) {
this.hdfsTmpDir = hdfsTmpDir;
}
@Override
public ConditionalResolverCommonJoinCtx clone() {
ConditionalResolverCommonJoinCtx ctx = new ConditionalResolverCommonJoinCtx();
ctx.setTaskToAliases(taskToAliases);
ctx.setCommonJoinTask(commonJoinTask);
ctx.setPathToAliases(pathToAliases);
ctx.setHdfsTmpDir(hdfsTmpDir);
ctx.setLocalTmpDir(localTmpDir);
// if any of join participants is from other MR, it has alias like '[pos:]$INTNAME'
// which of size should be caculated for each resolver.
ctx.setAliasToKnownSize(new HashMap(aliasToKnownSize));
return ctx;
}
}
public ConditionalResolverCommonJoin() {
}
@Override
public List> getTasks(HiveConf conf, Object objCtx) {
ConditionalResolverCommonJoinCtx ctx = ((ConditionalResolverCommonJoinCtx) objCtx).clone();
List> resTsks = new ArrayList>();
// get aliasToPath and pass it to the heuristic
Task task = resolveDriverAlias(ctx, conf);
if (task == null) {
// run common join task
resTsks.add(ctx.getCommonJoinTask());
} else {
// run the map join task, set task tag
if (task.getBackupTask() != null) {
task.getBackupTask().setTaskTag(Task.BACKUP_COMMON_JOIN);
}
resTsks.add(task);
}
return resTsks;
}
private Task resolveDriverAlias(ConditionalResolverCommonJoinCtx ctx, HiveConf conf) {
try {
resolveUnknownSizes(ctx, conf);
return resolveMapJoinTask(ctx, conf);
} catch (Exception e) {
LOG.info("Failed to resolve driver alias by exception.. Falling back to common join", e);
}
return null;
}
protected Task resolveMapJoinTask(
ConditionalResolverCommonJoinCtx ctx, HiveConf conf) throws Exception {
Set participants = getParticipants(ctx);
Map aliasToKnownSize = ctx.getAliasToKnownSize();
Map> pathToAliases = ctx.getPathToAliases();
Map, Set> taskToAliases = ctx.getTaskToAliases();
long threshold = HiveConf.getLongVar(conf, HiveConf.ConfVars.HIVESMALLTABLESFILESIZE);
Long bigTableSize = null;
Long smallTablesSize = null;
Map.Entry, Set> nextTask = null;
for (Map.Entry, Set> entry : taskToAliases.entrySet()) {
Set aliases = entry.getValue();
long sumOfOthers = Utilities.sumOfExcept(aliasToKnownSize, participants, aliases);
if (sumOfOthers < 0 || sumOfOthers > threshold) {
continue;
}
// at most one alias is unknown. we can safely regard it as a big alias
long aliasSize = Utilities.sumOf(aliasToKnownSize, aliases);
if (bigTableSize == null || aliasSize > bigTableSize) {
nextTask = entry;
bigTableSize = aliasSize;
smallTablesSize = sumOfOthers;
}
}
if (nextTask != null) {
LOG.info("Driver alias is " + nextTask.getValue() + " with size " + bigTableSize
+ " (total size of others : " + smallTablesSize + ", threshold : " + threshold + ")");
return nextTask.getKey();
}
LOG.info("Failed to resolve driver alias (threshold : " + threshold +
", length mapping : " + aliasToKnownSize + ")");
return null;
}
private Set getParticipants(ConditionalResolverCommonJoinCtx ctx) {
Set participants = new HashSet();
for (List aliases : ctx.getPathToAliases().values()) {
participants.addAll(aliases);
}
return participants;
}
protected void resolveUnknownSizes(ConditionalResolverCommonJoinCtx ctx, HiveConf conf)
throws Exception {
Set aliases = getParticipants(ctx);
Map aliasToKnownSize = ctx.getAliasToKnownSize();
Map> pathToAliases = ctx.getPathToAliases();
Set unknownPaths = new HashSet();
for (Map.Entry> entry : pathToAliases.entrySet()) {
for (String alias : entry.getValue()) {
if (aliases.contains(alias) && !aliasToKnownSize.containsKey(alias)) {
unknownPaths.add(entry.getKey());
break;
}
}
}
Path hdfsTmpDir = ctx.getHdfsTmpDir();
Path localTmpDir = ctx.getLocalTmpDir();
// need to compute the input size at runtime, and select the biggest as
// the big table.
for (String p : unknownPaths) {
// this path is intermediate data
if (p.startsWith(hdfsTmpDir.toString()) || p.startsWith(localTmpDir.toString())) {
Path path = new Path(p);
FileSystem fs = path.getFileSystem(conf);
long fileSize = fs.getContentSummary(path).getLength();
for (String alias : pathToAliases.get(p)) {
Long length = aliasToKnownSize.get(alias);
if (length == null) {
aliasToKnownSize.put(alias, fileSize);
}
}
}
}
}
}
