org.apache.hadoop.hive.ql.exec.FetchTask Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.hadoop.hive.ql.exec;
import org.apache.hadoop.hive.ql.Context;
import org.apache.hadoop.hive.ql.QueryPlan;
import org.apache.hadoop.hive.ql.QueryState;
import org.apache.hadoop.hive.ql.TaskQueue;
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.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
/**
* 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 List fetchedData;
private int currentRow;
private int totalRows;
private static final Logger LOG = LoggerFactory.getLogger(FetchTask.class);
JobConf job = null;
private boolean cachingEnabled = false;
public FetchTask() {
super();
}
public void setValidWriteIdList(String writeIdStr) {
fetch.setValidWriteIdList(writeIdStr);
}
@Override
public void initialize(QueryState queryState, QueryPlan queryPlan, TaskQueue taskQueue, Context context) {
super.initialize(queryState, queryPlan, taskQueue, context);
work.initializeForFetch(context.getOpContext());
fetchedData = new ArrayList<>();
try {
// Create a file system handle
job = new JobConf(conf);
initFetch();
} catch (Exception e) {
// Bail out ungracefully - we should never hit
// this here - but would have hit it in SemanticAnalyzer
LOG.error("Initialize failed", 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() {
if (cachingEnabled) {
executeInner(fetchedData);
}
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) {
if (cachingEnabled) {
if (currentRow >= fetchedData.size()) {
return false;
}
int toIndex = Math.min(fetchedData.size(), currentRow + maxRows);
res.addAll(fetchedData.subList(currentRow, toIndex));
currentRow = toIndex;
return true;
} else {
return executeInner(res);
}
}
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();
}
fetchedData.clear();
}
public void resetFetch() throws HiveException {
if (cachingEnabled) {
currentRow = 0;
} else {
clearFetch();
initFetch();
}
}
@Override
public boolean canExecuteInParallel() {
return false;
}
private boolean executeInner(List target) {
sink.reset(target);
int rowsRet;
if (cachingEnabled) {
rowsRet = work.getLimit() >= 0 ? work.getLimit() : Integer.MAX_VALUE;
} else {
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 HiveException("leastNumRows check failed");
}
// Closing the operator can sometimes yield more rows (HIVE-11892)
fetch.closeOperator();
return fetched;
}
fetched = true;
}
return true;
} catch (Exception e) {
console.printError("Failed with exception " + e.getClass().getName() + ":" + e.getMessage(),
"\n" + org.apache.hadoop.util.StringUtils.stringifyException(e));
throw new RuntimeException(e);
} finally {
totalRows += sink.getNumRows();
}
}
private void initFetch() throws HiveException {
Operator source = work.getSource();
if (source instanceof TableScanOperator) {
TableScanOperator ts = (TableScanOperator) source;
// push down projections
ColumnProjectionUtils.appendReadColumns(job, ts.getNeededColumnIDs(), ts.getNeededColumns(),
ts.getNeededNestedColumnPaths(), ts.getConf().hasVirtualCols());
// push down filters and as of information
HiveInputFormat.pushFiltersAndAsOf(job, ts, null);
AcidUtils.setAcidOperationalProperties(job, ts.getConf().isTranscationalTable(),
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);
}
public void setCachingEnabled(boolean cachingEnabled) {
this.cachingEnabled = cachingEnabled;
}
public boolean isCachingEnabled() {
return cachingEnabled;
}
}