/**
* 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.optimizer;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Stack;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hive.ql.exec.FilterOperator;
import org.apache.hadoop.hive.ql.exec.TableScanOperator;
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.lib.RuleRegExp;
import org.apache.hadoop.hive.ql.metadata.Hive;
import org.apache.hadoop.hive.ql.metadata.Partition;
import org.apache.hadoop.hive.ql.parse.ParseContext;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.plan.FilterDesc;
import org.apache.hadoop.hive.ql.plan.FilterDesc.SampleDesc;
/**
* The transformation step that does sample pruning.
*
*/
public class SamplePruner extends Transform {
/**
* SamplePrunerCtx.
*
*/
public static class SamplePrunerCtx implements NodeProcessorCtx {
HashMap<TableScanOperator, SampleDesc> opToSamplePruner;
public SamplePrunerCtx(
HashMap<TableScanOperator, SampleDesc> opToSamplePruner) {
this.opToSamplePruner = opToSamplePruner;
}
/**
* @return the opToSamplePruner
*/
public HashMap<TableScanOperator, SampleDesc> getOpToSamplePruner() {
return opToSamplePruner;
}
/**
* @param opToSamplePruner
* the opToSamplePruner to set
*/
public void setOpToSamplePruner(
HashMap<TableScanOperator, SampleDesc> opToSamplePruner) {
this.opToSamplePruner = opToSamplePruner;
}
}
// The log
private static final Logger LOG = LoggerFactory
.getLogger("hive.ql.optimizer.SamplePruner");
/*
* (non-Javadoc)
*
* @see
* org.apache.hadoop.hive.ql.optimizer.Transform#transform(org.apache.hadoop
* .hive.ql.parse.ParseContext)
*/
@Override
public ParseContext transform(ParseContext pctx) throws SemanticException {
// create a the context for walking operators
SamplePrunerCtx samplePrunerCtx = new SamplePrunerCtx(pctx
.getOpToSamplePruner());
Map<Rule, NodeProcessor> opRules = new LinkedHashMap<Rule, NodeProcessor>();
opRules.put(new RuleRegExp("R1",
"(" + TableScanOperator.getOperatorName() + "%"
+ FilterOperator.getOperatorName() + "%"
+ FilterOperator.getOperatorName() + "%|"
+ TableScanOperator.getOperatorName() + "%"
+ FilterOperator.getOperatorName() + "%)"), getFilterProc());
// The dispatcher fires the processor corresponding to the closest matching
// rule and passes the context along
Dispatcher disp = new DefaultRuleDispatcher(getDefaultProc(), opRules,
samplePrunerCtx);
GraphWalker ogw = new DefaultGraphWalker(disp);
// Create a list of topop nodes
ArrayList<Node> topNodes = new ArrayList<Node>();
topNodes.addAll(pctx.getTopOps().values());
ogw.startWalking(topNodes, null);
return pctx;
}
/**
* FilterPPR filter processor.
*
*/
public static class FilterPPR implements NodeProcessor {
@Override
public Object process(Node nd, Stack<Node> stack, NodeProcessorCtx procCtx,
Object... nodeOutputs) throws SemanticException {
FilterOperator filOp = (FilterOperator) nd;
FilterDesc filOpDesc = filOp.getConf();
SampleDesc sampleDescr = filOpDesc.getSampleDescr();
if ((sampleDescr == null) || !sampleDescr.getInputPruning()) {
return null;
}
assert (stack.size() == 3 && stack.get(1) instanceof FilterOperator) ||
stack.size() == 2;
TableScanOperator tsOp = (TableScanOperator) stack.get(0);
((SamplePrunerCtx) procCtx).getOpToSamplePruner().put(tsOp, sampleDescr);
return null;
}
}
public static NodeProcessor getFilterProc() {
return new FilterPPR();
}
/**
* DefaultPPR default processor which does nothing.
*
*/
public static class DefaultPPR implements NodeProcessor {
@Override
public Object process(Node nd, Stack<Node> stack, NodeProcessorCtx procCtx,
Object... nodeOutputs) throws SemanticException {
// Nothing needs to be done.
return null;
}
}
public static NodeProcessor getDefaultProc() {
return new DefaultPPR();
}
/**
* Prunes to get all the files in the partition that satisfy the TABLESAMPLE
* clause.
*
* @param part
* The partition to prune
* @return Path[]
* @throws SemanticException
*/
@SuppressWarnings("nls")
public static Path[] prune(Partition part, SampleDesc sampleDescr)
throws SemanticException {
int num = sampleDescr.getNumerator();
int den = sampleDescr.getDenominator();
int bucketCount = part.getBucketCount();
String fullScanMsg = "";
// check if input pruning is possible
if (sampleDescr.getInputPruning()) {
LOG.trace("numerator = " + num);
LOG.trace("denominator = " + den);
LOG.trace("bucket count = " + bucketCount);
if (bucketCount == den) {
Path[] ret = new Path[1];
ret[0] = part.getBucketPath(num - 1);
return (ret);
} else if (bucketCount > den && bucketCount % den == 0) {
int numPathsInSample = bucketCount / den;
Path[] ret = new Path[numPathsInSample];
for (int i = 0; i < numPathsInSample; i++) {
ret[i] = part.getBucketPath(i * den + num - 1);
}
return ret;
} else if (bucketCount < den && den % bucketCount == 0) {
Path[] ret = new Path[1];
ret[0] = part.getBucketPath((num - 1) % bucketCount);
return ret;
} else {
// need to do full scan
fullScanMsg = "Tablesample denominator " + den
+ " is not multiple/divisor of bucket count " + bucketCount
+ " of table " + part.getTable().getTableName();
}
} else {
// need to do full scan
fullScanMsg = "Tablesample not on clustered columns";
}
LOG.warn(fullScanMsg + ", using full table scan");
Path[] ret = part.getPath();
return ret;
}
/**
* Class used for return value of addPath()
*
*/
public static class AddPathReturnStatus {
public AddPathReturnStatus(boolean hasFile, boolean allFile, long sizeLeft) {
this.hasFile = hasFile;
this.allFile = allFile;
this.sizeLeft = sizeLeft;
}
// whether the sub-directory has any file
public boolean hasFile;
// whether all files are not sufficient to reach sizeLeft
public boolean allFile;
// remaining size needed after putting files in the return path list
public long sizeLeft;
}
/**
* Try to recursively add files in sub-directories into retPathList until
* reaching the sizeLeft.
* @param fs
* @param pathPattern
* @param sizeLeft
* @param fileLimit
* @param retPathList
* @return status of the recursive call
* @throws IOException
*/
public static AddPathReturnStatus addPath(FileSystem fs, String pathPattern, long sizeLeft, int fileLimit,
Collection<Path> retPathList)
throws IOException {
LOG.info("Path pattern = " + pathPattern);
FileStatus srcs[] = fs.globStatus(new Path(pathPattern));
Arrays.sort(srcs);
boolean hasFile = false, allFile = true;
for (FileStatus src : srcs) {
if (sizeLeft <= 0) {
allFile = false;
break;
}
if (src.isDir()) {
LOG.info("Got directory: " + src.getPath());
AddPathReturnStatus ret = addPath(fs, src.getPath().toString() + "/*", sizeLeft,
fileLimit, retPathList);
if (ret == null) {
// not qualify this optimization
return null;
}
sizeLeft = ret.sizeLeft;
hasFile |= ret.hasFile;
allFile &= ret.allFile;
} else {
LOG.info("Got file: " + src.getPath());
hasFile = true;
retPathList.add(src.getPath());
sizeLeft -= src.getLen();
if (retPathList.size() >= fileLimit && sizeLeft > 0) {
return null;
}
}
}
return new AddPathReturnStatus(hasFile, allFile, sizeLeft);
}
public enum LimitPruneRetStatus {
// no files in the partition
NoFile,
// sum size of all files in the partition is smaller than size required
NeedAllFiles,
// a susbset of files for the partition are sufficient for the optimization
NeedSomeFiles,
// the partition doesn't qualify the global limit optimization for some reason
NotQualify
}
/**
* Try to generate a list of subset of files in the partition to reach a size
* limit with number of files less than fileLimit
* @param part
* @param sizeLimit
* @param fileLimit
* @param retPathList list of Paths returned
* @return the result of the attempt
* @throws SemanticException
*/
public static LimitPruneRetStatus limitPrune(Partition part, long sizeLimit, int fileLimit,
Collection<Path> retPathList)
throws SemanticException {
try {
FileSystem fs = part.getDataLocation().getFileSystem(Hive.get().getConf());
String pathPattern = part.getDataLocation().toString() + "/*";
AddPathReturnStatus ret = addPath(fs, pathPattern, sizeLimit, fileLimit, retPathList);
if (ret == null) {
return LimitPruneRetStatus.NotQualify;
} else if (!ret.hasFile){
return LimitPruneRetStatus.NoFile;
} else if (ret.sizeLeft > 0) {
return LimitPruneRetStatus.NotQualify;
} else if (ret.allFile) {
return LimitPruneRetStatus.NeedAllFiles;
} else {
return LimitPruneRetStatus.NeedSomeFiles;
}
} catch (Exception e) {
throw new RuntimeException("Cannot get path", e);
}
}
}