org.apache.hadoop.hive.ql.exec.FetchTask Maven / Gradle / Ivy
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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.exec;
import java.io.IOException;
import java.io.Serializable;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.hive.ql.CommandNeedRetryException;
import org.apache.hadoop.hive.ql.CompilationOpContext;
import org.apache.hadoop.hive.ql.DriverContext;
import org.apache.hadoop.hive.ql.QueryPlan;
import org.apache.hadoop.hive.ql.QueryState;
import org.apache.hadoop.hive.ql.exec.mr.ExecMapper;
import org.apache.hadoop.hive.ql.io.AcidUtils;
import org.apache.hadoop.hive.ql.io.HiveInputFormat;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.metadata.VirtualColumn;
import org.apache.hadoop.hive.ql.plan.FetchWork;
import org.apache.hadoop.hive.ql.plan.FileSinkDesc;
import org.apache.hadoop.hive.ql.plan.TableDesc;
import org.apache.hadoop.hive.ql.plan.api.StageType;
import org.apache.hadoop.hive.serde2.ColumnProjectionUtils;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.util.StringUtils;
/**
* FetchTask implementation.
**/
public class FetchTask extends Task implements Serializable {
private static final long serialVersionUID = 1L;
private int maxRows = 100;
private FetchOperator fetch;
private ListSinkOperator sink;
private int totalRows;
private static transient final Logger LOG = LoggerFactory.getLogger(FetchTask.class);
public FetchTask() {
super();
}
public void setValidTxnList(String txnStr) {
fetch.setValidTxnList(txnStr);
}
@Override
public void initialize(QueryState queryState, QueryPlan queryPlan, DriverContext ctx,
CompilationOpContext opContext) {
super.initialize(queryState, queryPlan, ctx, opContext);
work.initializeForFetch(opContext);
try {
// Create a file system handle
JobConf job = new JobConf(conf);
Operator source = work.getSource();
if (source instanceof TableScanOperator) {
TableScanOperator ts = (TableScanOperator) source;
// push down projections
ColumnProjectionUtils.appendReadColumns(
job, ts.getNeededColumnIDs(), ts.getNeededColumns(), ts.getNeededNestedColumnPaths());
// push down filters
HiveInputFormat.pushFilters(job, ts);
AcidUtils.setTransactionalTableScan(job, ts.getConf().isAcidTable());
AcidUtils.setAcidOperationalProperties(job, ts.getConf().getAcidOperationalProperties());
}
sink = work.getSink();
fetch = new FetchOperator(work, job, source, getVirtualColumns(source));
source.initialize(conf, new ObjectInspector[]{fetch.getOutputObjectInspector()});
totalRows = 0;
ExecMapper.setDone(false);
} catch (Exception e) {
// Bail out ungracefully - we should never hit
// this here - but would have hit it in SemanticAnalyzer
LOG.error(StringUtils.stringifyException(e));
throw new RuntimeException(e);
}
}
private List getVirtualColumns(Operator ts) {
if (ts instanceof TableScanOperator && ts.getConf() != null) {
return ((TableScanOperator)ts).getConf().getVirtualCols();
}
return null;
}
@Override
public int execute(DriverContext driverContext) {
assert false;
return 0;
}
/**
* Return the tableDesc of the fetchWork.
*/
public TableDesc getTblDesc() {
return work.getTblDesc();
}
/**
* Return the maximum number of rows returned by fetch.
*/
public int getMaxRows() {
return maxRows;
}
/**
* Set the maximum number of rows returned by fetch.
*/
public void setMaxRows(int maxRows) {
this.maxRows = maxRows;
}
public boolean fetch(List res) throws IOException, CommandNeedRetryException {
sink.reset(res);
int rowsRet = work.getLeastNumRows();
if (rowsRet <= 0) {
rowsRet = work.getLimit() >= 0 ? Math.min(work.getLimit() - totalRows, maxRows) : maxRows;
}
try {
if (rowsRet <= 0 || work.getLimit() == totalRows) {
fetch.clearFetchContext();
return false;
}
boolean fetched = false;
while (sink.getNumRows() < rowsRet) {
if (!fetch.pushRow()) {
if (work.getLeastNumRows() > 0) {
throw new CommandNeedRetryException();
}
// Closing the operator can sometimes yield more rows (HIVE-11892)
fetch.closeOperator();
return fetched;
}
fetched = true;
}
return true;
} catch (CommandNeedRetryException e) {
throw e;
} catch (IOException e) {
throw e;
} catch (Exception e) {
throw new IOException(e);
} finally {
totalRows += sink.getNumRows();
}
}
public boolean isFetchFrom(FileSinkDesc fs) {
return fs.getFinalDirName().equals(work.getTblDir());
}
@Override
public StageType getType() {
return StageType.FETCH;
}
@Override
public String getName() {
return "FETCH";
}
/**
* Clear the Fetch Operator.
*
* @throws HiveException
*/
public void clearFetch() throws HiveException {
if (fetch != null) {
fetch.clearFetchContext();
}
}
}