/**
* 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.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.ql.exec.FetchTask;
import org.apache.hadoop.hive.ql.exec.FileSinkOperator;
import org.apache.hadoop.hive.ql.exec.FilterOperator;
import org.apache.hadoop.hive.ql.exec.LimitOperator;
import org.apache.hadoop.hive.ql.exec.ListSinkOperator;
import org.apache.hadoop.hive.ql.exec.Operator;
import org.apache.hadoop.hive.ql.exec.SelectOperator;
import org.apache.hadoop.hive.ql.exec.TableScanOperator;
import org.apache.hadoop.hive.ql.exec.TaskFactory;
import org.apache.hadoop.hive.ql.exec.Utilities;
import org.apache.hadoop.hive.ql.hooks.ReadEntity;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.metadata.Partition;
import org.apache.hadoop.hive.ql.metadata.Table;
import org.apache.hadoop.hive.ql.optimizer.ppr.PartitionPruner;
import org.apache.hadoop.hive.ql.parse.ParseContext;
import org.apache.hadoop.hive.ql.parse.PrunedPartitionList;
import org.apache.hadoop.hive.ql.parse.QB;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.parse.SplitSample;
import org.apache.hadoop.hive.ql.plan.ExprNodeDesc;
import org.apache.hadoop.hive.ql.plan.FetchWork;
import org.apache.hadoop.hive.ql.plan.ListSinkDesc;
import org.apache.hadoop.hive.ql.plan.OperatorDesc;
import org.apache.hadoop.hive.ql.plan.PartitionDesc;
import org.apache.hadoop.hive.ql.plan.PlanUtils;
import org.apache.hadoop.hive.ql.plan.TableDesc;
/**
* Tries to convert simple fetch query to single fetch task, which fetches rows directly
* from location of table/partition.
*/
public class SimpleFetchOptimizer implements Transform {
private final Log LOG = LogFactory.getLog(SimpleFetchOptimizer.class.getName());
public ParseContext transform(ParseContext pctx) throws SemanticException {
Map<String, Operator<? extends OperatorDesc>> topOps = pctx.getTopOps();
if (pctx.getQB().isSimpleSelectQuery() && topOps.size() == 1) {
// no join, no groupby, no distinct, no lateral view, no subq,
// no CTAS or insert, not analyze command, and single sourced.
String alias = (String) pctx.getTopOps().keySet().toArray()[0];
Operator topOp = (Operator) pctx.getTopOps().values().toArray()[0];
if (topOp instanceof TableScanOperator) {
try {
FetchTask fetchTask = optimize(pctx, alias, (TableScanOperator) topOp);
if (fetchTask != null) {
pctx.setFetchTask(fetchTask);
}
} catch (HiveException e) {
// Has to use full name to make sure it does not conflict with
// org.apache.commons.lang.StringUtils
LOG.error(org.apache.hadoop.util.StringUtils.stringifyException(e));
if (e instanceof SemanticException) {
throw (SemanticException) e;
}
throw new SemanticException(e.getMessage(), e);
}
}
}
return pctx;
}
// returns non-null FetchTask instance when succeeded
@SuppressWarnings("unchecked")
private FetchTask optimize(ParseContext pctx, String alias, TableScanOperator source)
throws HiveException {
String mode = HiveConf.getVar(
pctx.getConf(), HiveConf.ConfVars.HIVEFETCHTASKCONVERSION);
boolean aggressive = "more".equals(mode);
FetchData fetch = checkTree(aggressive, pctx, alias, source);
if (fetch != null) {
int limit = pctx.getQB().getParseInfo().getOuterQueryLimit();
FetchWork fetchWork = fetch.convertToWork();
FetchTask fetchTask = (FetchTask) TaskFactory.get(fetchWork, pctx.getConf());
fetchWork.setSink(fetch.completed(pctx, fetchWork));
fetchWork.setSource(source);
fetchWork.setLimit(limit);
return fetchTask;
}
return null;
}
// all we can handle is LimitOperator, FilterOperator SelectOperator and final FS
//
// for non-aggressive mode (minimal)
// 1. samping is not allowed
// 2. for partitioned table, all filters should be targeted to partition column
// 3. SelectOperator should be select star
private FetchData checkTree(boolean aggressive, ParseContext pctx, String alias,
TableScanOperator ts) throws HiveException {
SplitSample splitSample = pctx.getNameToSplitSample().get(alias);
if (!aggressive && splitSample != null) {
return null;
}
QB qb = pctx.getQB();
if (!aggressive && qb.hasTableSample(alias)) {
return null;
}
Table table = qb.getMetaData().getAliasToTable().get(alias);
if (table == null) {
return null;
}
if (!table.isPartitioned()) {
return checkOperators(new FetchData(table, splitSample), ts, aggressive, false);
}
boolean bypassFilter = false;
if (HiveConf.getBoolVar(pctx.getConf(), HiveConf.ConfVars.HIVEOPTPPD)) {
ExprNodeDesc pruner = pctx.getOpToPartPruner().get(ts);
bypassFilter = PartitionPruner.onlyContainsPartnCols(table, pruner);
}
if (aggressive || bypassFilter) {
PrunedPartitionList pruned = pctx.getPrunedPartitions(alias, ts);
if (aggressive || !pruned.hasUnknownPartitions()) {
bypassFilter &= !pruned.hasUnknownPartitions();
return checkOperators(new FetchData(pruned, splitSample), ts, aggressive, bypassFilter);
}
}
return null;
}
private FetchData checkOperators(FetchData fetch, TableScanOperator ts, boolean aggresive,
boolean bypassFilter) {
if (ts.getChildOperators().size() != 1) {
return null;
}
Operator<?> op = ts.getChildOperators().get(0);
for (; ; op = op.getChildOperators().get(0)) {
if (aggresive) {
if (!(op instanceof LimitOperator || op instanceof FilterOperator
|| op instanceof SelectOperator)) {
break;
}
} else if (!(op instanceof LimitOperator || (op instanceof FilterOperator && bypassFilter)
|| (op instanceof SelectOperator && ((SelectOperator) op).getConf().isSelectStar()))) {
break;
}
if (op.getChildOperators() == null || op.getChildOperators().size() != 1) {
return null;
}
}
if (op instanceof FileSinkOperator) {
fetch.fileSink = op;
return fetch;
}
return null;
}
private class FetchData {
private final Table table;
private final SplitSample splitSample;
private final PrunedPartitionList partsList;
private final HashSet<ReadEntity> inputs = new HashSet<ReadEntity>();
// this is always non-null when conversion is completed
private Operator<?> fileSink;
private FetchData(Table table, SplitSample splitSample) {
this.table = table;
this.partsList = null;
this.splitSample = splitSample;
}
private FetchData(PrunedPartitionList partsList, SplitSample splitSample) {
this.table = null;
this.partsList = partsList;
this.splitSample = splitSample;
}
private FetchWork convertToWork() throws HiveException {
inputs.clear();
if (table != null) {
inputs.add(new ReadEntity(table));
String path = table.getPath().toString();
FetchWork work = new FetchWork(path, Utilities.getTableDesc(table));
PlanUtils.configureInputJobPropertiesForStorageHandler(work.getTblDesc());
work.setSplitSample(splitSample);
return work;
}
List<String> listP = new ArrayList<String>();
List<PartitionDesc> partP = new ArrayList<PartitionDesc>();
for (Partition partition : partsList.getNotDeniedPartns()) {
inputs.add(new ReadEntity(partition));
listP.add(partition.getPartitionPath().toString());
partP.add(Utilities.getPartitionDesc(partition));
}
Table sourceTable = partsList.getSourceTable();
inputs.add(new ReadEntity(sourceTable));
TableDesc table = Utilities.getTableDesc(sourceTable);
FetchWork work = new FetchWork(listP, partP, table);
if (!work.getPartDesc().isEmpty()) {
PartitionDesc part0 = work.getPartDesc().get(0);
PlanUtils.configureInputJobPropertiesForStorageHandler(part0.getTableDesc());
work.setSplitSample(splitSample);
}
return work;
}
// this optimizer is for replacing FS to temp+fetching from temp with
// single direct fetching, which means FS is not needed any more when conversion completed.
// rows forwarded will be received by ListSinkOperator, which is replacing FS
private ListSinkOperator completed(ParseContext pctx, FetchWork work) {
pctx.getSemanticInputs().addAll(inputs);
return replaceFSwithLS(fileSink, work.getSerializationNullFormat());
}
}
public static ListSinkOperator replaceFSwithLS(Operator<?> fileSink, String nullFormat) {
ListSinkOperator sink = new ListSinkOperator();
sink.setConf(new ListSinkDesc(nullFormat));
sink.setParentOperators(new ArrayList<Operator<? extends OperatorDesc>>());
Operator<? extends OperatorDesc> parent = fileSink.getParentOperators().get(0);
sink.getParentOperators().add(parent);
parent.replaceChild(fileSink, sink);
fileSink.setParentOperators(null);
return sink;
}
}