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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.cassandra.db;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import com.google.common.annotations.VisibleForTesting;
import org.apache.cassandra.net.Verb;
import org.apache.cassandra.schema.TableMetadata;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.filter.*;
import org.apache.cassandra.db.lifecycle.View;
import org.apache.cassandra.db.partitions.*;
import org.apache.cassandra.db.rows.BaseRowIterator;
import org.apache.cassandra.db.transform.RTBoundValidator;
import org.apache.cassandra.db.transform.Transformation;
import org.apache.cassandra.dht.AbstractBounds;
import org.apache.cassandra.dht.Bounds;
import org.apache.cassandra.exceptions.RequestExecutionException;
import org.apache.cassandra.index.Index;
import org.apache.cassandra.io.sstable.format.SSTableReader;
import org.apache.cassandra.io.sstable.format.SSTableReadsListener;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.metrics.TableMetrics;
import org.apache.cassandra.schema.IndexMetadata;
import org.apache.cassandra.service.ClientState;
import org.apache.cassandra.service.StorageProxy;
import org.apache.cassandra.tracing.Tracing;
/**
* A read command that selects a (part of a) range of partitions.
*/
public class PartitionRangeReadCommand extends ReadCommand implements PartitionRangeReadQuery
{
protected static final SelectionDeserializer selectionDeserializer = new Deserializer();
private final DataRange dataRange;
private PartitionRangeReadCommand(boolean isDigest,
int digestVersion,
boolean acceptsTransient,
TableMetadata metadata,
int nowInSec,
ColumnFilter columnFilter,
RowFilter rowFilter,
DataLimits limits,
DataRange dataRange,
IndexMetadata index)
{
super(Kind.PARTITION_RANGE, isDigest, digestVersion, acceptsTransient, metadata, nowInSec, columnFilter, rowFilter, limits, index);
this.dataRange = dataRange;
}
public static PartitionRangeReadCommand create(TableMetadata metadata,
int nowInSec,
ColumnFilter columnFilter,
RowFilter rowFilter,
DataLimits limits,
DataRange dataRange)
{
return new PartitionRangeReadCommand(false,
0,
false,
metadata,
nowInSec,
columnFilter,
rowFilter,
limits,
dataRange,
findIndex(metadata, rowFilter));
}
/**
* Creates a new read command that query all the data in the table.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
*
* @return a newly created read command that queries everything in the table.
*/
public static PartitionRangeReadCommand allDataRead(TableMetadata metadata, int nowInSec)
{
return new PartitionRangeReadCommand(false,
0,
false,
metadata,
nowInSec,
ColumnFilter.all(metadata),
RowFilter.NONE,
DataLimits.NONE,
DataRange.allData(metadata.partitioner),
null);
}
public DataRange dataRange()
{
return dataRange;
}
public ClusteringIndexFilter clusteringIndexFilter(DecoratedKey key)
{
return dataRange.clusteringIndexFilter(key);
}
public boolean isNamesQuery()
{
return dataRange.isNamesQuery();
}
/**
* Returns an equivalent command but that only queries data within the provided range.
*
* @param range the sub-range to restrict the command to. This method assumes that this is a proper sub-range
* of the command this is applied to.
* @param isRangeContinuation whether {@code range} is a direct continuation of whatever previous range we have
* queried. This matters for the {@code DataLimits} that may contain states when we do paging and in the context of
* parallel queries: that state only make sense if the range queried is indeed the follow-up of whatever range we've
* previously query (that yield said state). In practice this means that ranges for which {@code isRangeContinuation}
* is false may have to be slightly pessimistic when counting data and may include a little bit than necessary, and
* this should be dealt with post-query (in the case of {@code StorageProxy.getRangeSlice()}, which uses this method
* for replica queries, this is dealt with by re-counting results on the coordinator). Note that if this is the
* first range we queried, then the {@code DataLimits} will have not state and the value of this parameter doesn't
* matter.
*/
public PartitionRangeReadCommand forSubRange(AbstractBounds range, boolean isRangeContinuation)
{
// If we're not a continuation of whatever range we've previously queried, we should ignore the states of the
// DataLimits as it's either useless, or misleading. This is particularly important for GROUP BY queries, where
// DataLimits.CQLGroupByLimits.GroupByAwareCounter assumes that if GroupingState.hasClustering(), then we're in
// the middle of a group, but we can't make that assumption if we query and range "in advance" of where we are
// on the ring.
return new PartitionRangeReadCommand(isDigestQuery(),
digestVersion(),
acceptsTransient(),
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
isRangeContinuation ? limits() : limits().withoutState(),
dataRange().forSubRange(range),
indexMetadata());
}
public PartitionRangeReadCommand copy()
{
return new PartitionRangeReadCommand(isDigestQuery(),
digestVersion(),
acceptsTransient(),
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
limits(),
dataRange(),
indexMetadata());
}
@Override
protected PartitionRangeReadCommand copyAsDigestQuery()
{
return new PartitionRangeReadCommand(true,
digestVersion(),
false,
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
limits(),
dataRange(),
indexMetadata());
}
@Override
protected PartitionRangeReadCommand copyAsTransientQuery()
{
return new PartitionRangeReadCommand(false,
0,
true,
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
limits(),
dataRange(),
indexMetadata());
}
@Override
public PartitionRangeReadCommand withUpdatedLimit(DataLimits newLimits)
{
return new PartitionRangeReadCommand(isDigestQuery(),
digestVersion(),
acceptsTransient(),
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
newLimits,
dataRange(),
indexMetadata());
}
@Override
public PartitionRangeReadCommand withUpdatedLimitsAndDataRange(DataLimits newLimits, DataRange newDataRange)
{
return new PartitionRangeReadCommand(isDigestQuery(),
digestVersion(),
acceptsTransient(),
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
newLimits,
newDataRange,
indexMetadata());
}
public long getTimeout(TimeUnit unit)
{
return DatabaseDescriptor.getRangeRpcTimeout(unit);
}
public boolean isReversed()
{
return dataRange.isReversed();
}
public PartitionIterator execute(ConsistencyLevel consistency, ClientState clientState, long queryStartNanoTime) throws RequestExecutionException
{
return StorageProxy.getRangeSlice(this, consistency, queryStartNanoTime);
}
protected void recordLatency(TableMetrics metric, long latencyNanos)
{
metric.rangeLatency.addNano(latencyNanos);
}
@VisibleForTesting
public UnfilteredPartitionIterator queryStorage(final ColumnFamilyStore cfs, ReadExecutionController controller)
{
ColumnFamilyStore.ViewFragment view = cfs.select(View.selectLive(dataRange().keyRange()));
Tracing.trace("Executing seq scan across {} sstables for {}", view.sstables.size(), dataRange().keyRange().getString(metadata().partitionKeyType));
// fetch data from current memtable, historical memtables, and SSTables in the correct order.
InputCollector inputCollector = iteratorsForRange(view, controller);
try
{
for (Memtable memtable : view.memtables)
{
@SuppressWarnings("resource") // We close on exception and on closing the result returned by this method
Memtable.MemtableUnfilteredPartitionIterator iter = memtable.makePartitionIterator(columnFilter(), dataRange());
controller.updateMinOldestUnrepairedTombstone(iter.getMinLocalDeletionTime());
inputCollector.addMemtableIterator(RTBoundValidator.validate(iter, RTBoundValidator.Stage.MEMTABLE, false));
}
SSTableReadsListener readCountUpdater = newReadCountUpdater();
for (SSTableReader sstable : view.sstables)
{
@SuppressWarnings("resource") // We close on exception and on closing the result returned by this method
UnfilteredPartitionIterator iter = sstable.getScanner(columnFilter(), dataRange(), readCountUpdater);
inputCollector.addSSTableIterator(sstable, RTBoundValidator.validate(iter, RTBoundValidator.Stage.SSTABLE, false));
if (!sstable.isRepaired())
controller.updateMinOldestUnrepairedTombstone(sstable.getMinLocalDeletionTime());
}
// iterators can be empty for offline tools
if (inputCollector.isEmpty())
return EmptyIterators.unfilteredPartition(metadata());
return checkCacheFilter(UnfilteredPartitionIterators.mergeLazily(inputCollector.finalizeIterators(cfs, nowInSec(), controller.oldestUnrepairedTombstone())), cfs);
}
catch (RuntimeException | Error e)
{
try
{
inputCollector.close();
}
catch (Exception e1)
{
e.addSuppressed(e1);
}
throw e;
}
}
/**
* Creates a new {@code SSTableReadsListener} to update the SSTables read counts.
* @return a new {@code SSTableReadsListener} to update the SSTables read counts.
*/
private static SSTableReadsListener newReadCountUpdater()
{
return new SSTableReadsListener()
{
@Override
public void onScanningStarted(SSTableReader sstable)
{
sstable.incrementReadCount();
}
};
}
private UnfilteredPartitionIterator checkCacheFilter(UnfilteredPartitionIterator iter, final ColumnFamilyStore cfs)
{
class CacheFilter extends Transformation>
{
@Override
public BaseRowIterator applyToPartition(BaseRowIterator iter)
{
// Note that we rely on the fact that until we actually advance 'iter', no really costly operation is actually done
// (except for reading the partition key from the index file) due to the call to mergeLazily in queryStorage.
DecoratedKey dk = iter.partitionKey();
// Check if this partition is in the rowCache and if it is, if it covers our filter
CachedPartition cached = cfs.getRawCachedPartition(dk);
ClusteringIndexFilter filter = dataRange().clusteringIndexFilter(dk);
if (cached != null && cfs.isFilterFullyCoveredBy(filter,
limits(),
cached,
nowInSec(),
iter.metadata().enforceStrictLiveness()))
{
// We won't use 'iter' so close it now.
iter.close();
return filter.getUnfilteredRowIterator(columnFilter(), cached);
}
return iter;
}
}
return Transformation.apply(iter, new CacheFilter());
}
@Override
public Verb verb()
{
return Verb.RANGE_REQ;
}
protected void appendCQLWhereClause(StringBuilder sb)
{
if (dataRange.isUnrestricted() && rowFilter().isEmpty())
return;
sb.append(" WHERE ");
// We put the row filter first because the data range can end by "ORDER BY"
if (!rowFilter().isEmpty())
{
sb.append(rowFilter());
if (!dataRange.isUnrestricted())
sb.append(" AND ");
}
if (!dataRange.isUnrestricted())
sb.append(dataRange.toCQLString(metadata()));
}
/**
* Allow to post-process the result of the query after it has been reconciled on the coordinator
* but before it is passed to the CQL layer to return the ResultSet.
*
* See CASSANDRA-8717 for why this exists.
*/
public PartitionIterator postReconciliationProcessing(PartitionIterator result)
{
ColumnFamilyStore cfs = Keyspace.open(metadata().keyspace).getColumnFamilyStore(metadata().name);
Index index = getIndex(cfs);
return index == null ? result : index.postProcessorFor(this).apply(result, this);
}
@Override
public String toString()
{
return String.format("Read(%s columns=%s rowfilter=%s limits=%s %s)",
metadata().toString(),
columnFilter(),
rowFilter(),
limits(),
dataRange().toString(metadata()));
}
protected void serializeSelection(DataOutputPlus out, int version) throws IOException
{
DataRange.serializer.serialize(dataRange(), out, version, metadata());
}
protected long selectionSerializedSize(int version)
{
return DataRange.serializer.serializedSize(dataRange(), version, metadata());
}
/*
* We are currently using PartitionRangeReadCommand for most index queries, even if they are explicitly restricted
* to a single partition key. Return true if that is the case.
*
* See CASSANDRA-11617 and CASSANDRA-11872 for details.
*/
public boolean isLimitedToOnePartition()
{
return dataRange.keyRange instanceof Bounds
&& dataRange.startKey().kind() == PartitionPosition.Kind.ROW_KEY
&& dataRange.startKey().equals(dataRange.stopKey());
}
public boolean isRangeRequest()
{
return true;
}
private static class Deserializer extends SelectionDeserializer
{
public ReadCommand deserialize(DataInputPlus in,
int version,
boolean isDigest,
int digestVersion,
boolean acceptsTransient,
TableMetadata metadata,
int nowInSec,
ColumnFilter columnFilter,
RowFilter rowFilter,
DataLimits limits,
IndexMetadata index)
throws IOException
{
DataRange range = DataRange.serializer.deserialize(in, version, metadata);
return new PartitionRangeReadCommand(isDigest, digestVersion, acceptsTransient, metadata, nowInSec, columnFilter, rowFilter, limits, range, index);
}
}
}