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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.cassandra.db;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.*;
import java.util.concurrent.TimeUnit;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.Sets;
import org.apache.cassandra.cache.IRowCacheEntry;
import org.apache.cassandra.cache.RowCacheKey;
import org.apache.cassandra.cache.RowCacheSentinel;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.filter.*;
import org.apache.cassandra.db.lifecycle.*;
import org.apache.cassandra.db.partitions.*;
import org.apache.cassandra.db.rows.*;
import org.apache.cassandra.db.transform.RTBoundValidator;
import org.apache.cassandra.db.transform.Transformation;
import org.apache.cassandra.exceptions.RequestExecutionException;
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.net.Verb;
import org.apache.cassandra.schema.ColumnMetadata;
import org.apache.cassandra.schema.IndexMetadata;
import org.apache.cassandra.schema.TableMetadata;
import org.apache.cassandra.service.*;
import org.apache.cassandra.tracing.Tracing;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.btree.BTreeSet;
/**
* A read command that selects a (part of a) single partition.
*/
public class SinglePartitionReadCommand extends ReadCommand implements SinglePartitionReadQuery
{
protected static final SelectionDeserializer selectionDeserializer = new Deserializer();
private final DecoratedKey partitionKey;
private final ClusteringIndexFilter clusteringIndexFilter;
@VisibleForTesting
protected SinglePartitionReadCommand(boolean isDigest,
int digestVersion,
boolean acceptsTransient,
TableMetadata metadata,
int nowInSec,
ColumnFilter columnFilter,
RowFilter rowFilter,
DataLimits limits,
DecoratedKey partitionKey,
ClusteringIndexFilter clusteringIndexFilter,
IndexMetadata index)
{
super(Kind.SINGLE_PARTITION, isDigest, digestVersion, acceptsTransient, metadata, nowInSec, columnFilter, rowFilter, limits, index);
assert partitionKey.getPartitioner() == metadata.partitioner;
this.partitionKey = partitionKey;
this.clusteringIndexFilter = clusteringIndexFilter;
}
/**
* Creates a new read command on a single partition.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param columnFilter the column filter to use for the query.
* @param rowFilter the row filter to use for the query.
* @param limits the limits to use for the query.
* @param partitionKey the partition key for the partition to query.
* @param clusteringIndexFilter the clustering index filter to use for the query.
* @param indexMetadata explicitly specified index to use for the query
*
* @return a newly created read command.
*/
public static SinglePartitionReadCommand create(TableMetadata metadata,
int nowInSec,
ColumnFilter columnFilter,
RowFilter rowFilter,
DataLimits limits,
DecoratedKey partitionKey,
ClusteringIndexFilter clusteringIndexFilter,
IndexMetadata indexMetadata)
{
return new SinglePartitionReadCommand(false,
0,
false,
metadata,
nowInSec,
columnFilter,
rowFilter,
limits,
partitionKey,
clusteringIndexFilter,
indexMetadata);
}
/**
* Creates a new read command on a single partition.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param columnFilter the column filter to use for the query.
* @param rowFilter the row filter to use for the query.
* @param limits the limits to use for the query.
* @param partitionKey the partition key for the partition to query.
* @param clusteringIndexFilter the clustering index filter to use for the query.
*
* @return a newly created read command.
*/
public static SinglePartitionReadCommand create(TableMetadata metadata,
int nowInSec,
ColumnFilter columnFilter,
RowFilter rowFilter,
DataLimits limits,
DecoratedKey partitionKey,
ClusteringIndexFilter clusteringIndexFilter)
{
return create(metadata,
nowInSec,
columnFilter,
rowFilter,
limits,
partitionKey,
clusteringIndexFilter,
findIndex(metadata, rowFilter));
}
/**
* Creates a new read command on a single partition.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param key the partition key for the partition to query.
* @param columnFilter the column filter to use for the query.
* @param filter the clustering index filter to use for the query.
*
* @return a newly created read command. The returned command will use no row filter and have no limits.
*/
public static SinglePartitionReadCommand create(TableMetadata metadata,
int nowInSec,
DecoratedKey key,
ColumnFilter columnFilter,
ClusteringIndexFilter filter)
{
return create(metadata, nowInSec, columnFilter, RowFilter.NONE, DataLimits.NONE, key, filter);
}
/**
* Creates a new read command that queries a single partition in its entirety.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param key the partition key for the partition to query.
*
* @return a newly created read command that queries all the rows of {@code key}.
*/
public static SinglePartitionReadCommand fullPartitionRead(TableMetadata metadata, int nowInSec, DecoratedKey key)
{
return create(metadata, nowInSec, key, Slices.ALL);
}
/**
* Creates a new read command that queries a single partition in its entirety.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param key the partition key for the partition to query.
*
* @return a newly created read command that queries all the rows of {@code key}.
*/
public static SinglePartitionReadCommand fullPartitionRead(TableMetadata metadata, int nowInSec, ByteBuffer key)
{
return create(metadata, nowInSec, metadata.partitioner.decorateKey(key), Slices.ALL);
}
/**
* Creates a new single partition slice command for the provided single slice.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param key the partition key for the partition to query.
* @param slice the slice of rows to query.
*
* @return a newly created read command that queries {@code slice} in {@code key}. The returned query will
* query every columns for the table (without limit or row filtering) and be in forward order.
*/
public static SinglePartitionReadCommand create(TableMetadata metadata, int nowInSec, DecoratedKey key, Slice slice)
{
return create(metadata, nowInSec, key, Slices.with(metadata.comparator, slice));
}
/**
* Creates a new single partition slice command for the provided slices.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param key the partition key for the partition to query.
* @param slices the slices of rows to query.
*
* @return a newly created read command that queries the {@code slices} in {@code key}. The returned query will
* query every columns for the table (without limit or row filtering) and be in forward order.
*/
public static SinglePartitionReadCommand create(TableMetadata metadata, int nowInSec, DecoratedKey key, Slices slices)
{
ClusteringIndexSliceFilter filter = new ClusteringIndexSliceFilter(slices, false);
return create(metadata, nowInSec, ColumnFilter.all(metadata), RowFilter.NONE, DataLimits.NONE, key, filter);
}
/**
* Creates a new single partition slice command for the provided slices.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param key the partition key for the partition to query.
* @param slices the slices of rows to query.
*
* @return a newly created read command that queries the {@code slices} in {@code key}. The returned query will
* query every columns for the table (without limit or row filtering) and be in forward order.
*/
public static SinglePartitionReadCommand create(TableMetadata metadata, int nowInSec, ByteBuffer key, Slices slices)
{
return create(metadata, nowInSec, metadata.partitioner.decorateKey(key), slices);
}
/**
* Creates a new single partition name command for the provided rows.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param key the partition key for the partition to query.
* @param names the clustering for the rows to query.
*
* @return a newly created read command that queries the {@code names} in {@code key}. The returned query will
* query every columns (without limit or row filtering) and be in forward order.
*/
public static SinglePartitionReadCommand create(TableMetadata metadata, int nowInSec, DecoratedKey key, NavigableSet> names)
{
ClusteringIndexNamesFilter filter = new ClusteringIndexNamesFilter(names, false);
return create(metadata, nowInSec, ColumnFilter.all(metadata), RowFilter.NONE, DataLimits.NONE, key, filter);
}
/**
* Creates a new single partition name command for the provided row.
*
* @param metadata the table to query.
* @param nowInSec the time in seconds to use are "now" for this query.
* @param key the partition key for the partition to query.
* @param name the clustering for the row to query.
*
* @return a newly created read command that queries {@code name} in {@code key}. The returned query will
* query every columns (without limit or row filtering).
*/
public static SinglePartitionReadCommand create(TableMetadata metadata, int nowInSec, DecoratedKey key, Clustering name)
{
return create(metadata, nowInSec, key, FBUtilities.singleton(name, metadata.comparator));
}
public SinglePartitionReadCommand copy()
{
return new SinglePartitionReadCommand(isDigestQuery(),
digestVersion(),
acceptsTransient(),
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
limits(),
partitionKey(),
clusteringIndexFilter(),
indexMetadata());
}
@Override
protected SinglePartitionReadCommand copyAsDigestQuery()
{
return new SinglePartitionReadCommand(true,
digestVersion(),
acceptsTransient(),
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
limits(),
partitionKey(),
clusteringIndexFilter(),
indexMetadata());
}
@Override
protected SinglePartitionReadCommand copyAsTransientQuery()
{
return new SinglePartitionReadCommand(false,
0,
true,
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
limits(),
partitionKey(),
clusteringIndexFilter(),
indexMetadata());
}
@Override
public SinglePartitionReadCommand withUpdatedLimit(DataLimits newLimits)
{
return new SinglePartitionReadCommand(isDigestQuery(),
digestVersion(),
acceptsTransient(),
metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
newLimits,
partitionKey(),
clusteringIndexFilter(),
indexMetadata());
}
@Override
public DecoratedKey partitionKey()
{
return partitionKey;
}
@Override
public ClusteringIndexFilter clusteringIndexFilter()
{
return clusteringIndexFilter;
}
public ClusteringIndexFilter clusteringIndexFilter(DecoratedKey key)
{
return clusteringIndexFilter;
}
public long getTimeout(TimeUnit unit)
{
return DatabaseDescriptor.getReadRpcTimeout(unit);
}
public boolean isReversed()
{
return clusteringIndexFilter.isReversed();
}
@Override
public SinglePartitionReadCommand forPaging(Clustering lastReturned, DataLimits limits)
{
// We shouldn't have set digest yet when reaching that point
assert !isDigestQuery();
return create(metadata(),
nowInSec(),
columnFilter(),
rowFilter(),
limits,
partitionKey(),
lastReturned == null ? clusteringIndexFilter() : clusteringIndexFilter.forPaging(metadata().comparator, lastReturned, false));
}
public PartitionIterator execute(ConsistencyLevel consistency, ClientState clientState, long queryStartNanoTime) throws RequestExecutionException
{
if (clusteringIndexFilter.isEmpty(metadata().comparator))
return EmptyIterators.partition();
return StorageProxy.read(Group.one(this), consistency, clientState, queryStartNanoTime);
}
protected void recordLatency(TableMetrics metric, long latencyNanos)
{
metric.readLatency.addNano(latencyNanos);
}
@SuppressWarnings("resource") // we close the created iterator through closing the result of this method (and SingletonUnfilteredPartitionIterator ctor cannot fail)
protected UnfilteredPartitionIterator queryStorage(final ColumnFamilyStore cfs, ReadExecutionController executionController)
{
// skip the row cache and go directly to sstables/memtable if repaired status of
// data is being tracked. This is only requested after an initial digest mismatch
UnfilteredRowIterator partition = cfs.isRowCacheEnabled() && !executionController.isTrackingRepairedStatus()
? getThroughCache(cfs, executionController)
: queryMemtableAndDisk(cfs, executionController);
return new SingletonUnfilteredPartitionIterator(partition);
}
/**
* Fetch the rows requested if in cache; if not, read it from disk and cache it.
*
* If the partition is cached, and the filter given is within its bounds, we return
* from cache, otherwise from disk.
*
* If the partition is is not cached, we figure out what filter is "biggest", read
* that from disk, then filter the result and either cache that or return it.
*/
@SuppressWarnings("resource")
private UnfilteredRowIterator getThroughCache(ColumnFamilyStore cfs, ReadExecutionController executionController)
{
assert !cfs.isIndex(); // CASSANDRA-5732
assert cfs.isRowCacheEnabled() : String.format("Row cache is not enabled on table [%s]", cfs.name);
RowCacheKey key = new RowCacheKey(metadata(), partitionKey());
// Attempt a sentinel-read-cache sequence. if a write invalidates our sentinel, we'll return our
// (now potentially obsolete) data, but won't cache it. see CASSANDRA-3862
// TODO: don't evict entire partitions on writes (#2864)
IRowCacheEntry cached = CacheService.instance.rowCache.get(key);
if (cached != null)
{
if (cached instanceof RowCacheSentinel)
{
// Some other read is trying to cache the value, just do a normal non-caching read
Tracing.trace("Row cache miss (race)");
cfs.metric.rowCacheMiss.inc();
return queryMemtableAndDisk(cfs, executionController);
}
CachedPartition cachedPartition = (CachedPartition)cached;
if (cfs.isFilterFullyCoveredBy(clusteringIndexFilter(), limits(), cachedPartition, nowInSec(), metadata().enforceStrictLiveness()))
{
cfs.metric.rowCacheHit.inc();
Tracing.trace("Row cache hit");
UnfilteredRowIterator unfilteredRowIterator = clusteringIndexFilter().getUnfilteredRowIterator(columnFilter(), cachedPartition);
cfs.metric.updateSSTableIterated(0);
return unfilteredRowIterator;
}
cfs.metric.rowCacheHitOutOfRange.inc();
Tracing.trace("Ignoring row cache as cached value could not satisfy query");
return queryMemtableAndDisk(cfs, executionController);
}
cfs.metric.rowCacheMiss.inc();
Tracing.trace("Row cache miss");
// Note that on tables with no clustering keys, any positive value of
// rowsToCache implies caching the full partition
boolean cacheFullPartitions = metadata().clusteringColumns().size() > 0 ?
metadata().params.caching.cacheAllRows() :
metadata().params.caching.cacheRows();
// To be able to cache what we read, what we read must at least covers what the cache holds, that
// is the 'rowsToCache' first rows of the partition. We could read those 'rowsToCache' first rows
// systematically, but we'd have to "extend" that to whatever is needed for the user query that the
// 'rowsToCache' first rows don't cover and it's not trivial with our existing filters. So currently
// we settle for caching what we read only if the user query does query the head of the partition since
// that's the common case of when we'll be able to use the cache anyway. One exception is if we cache
// full partitions, in which case we just always read it all and cache.
if (cacheFullPartitions || clusteringIndexFilter().isHeadFilter())
{
RowCacheSentinel sentinel = new RowCacheSentinel();
boolean sentinelSuccess = CacheService.instance.rowCache.putIfAbsent(key, sentinel);
boolean sentinelReplaced = false;
try
{
final int rowsToCache = metadata().params.caching.rowsPerPartitionToCache();
final boolean enforceStrictLiveness = metadata().enforceStrictLiveness();
@SuppressWarnings("resource") // we close on exception or upon closing the result of this method
UnfilteredRowIterator iter = fullPartitionRead(metadata(), nowInSec(), partitionKey()).queryMemtableAndDisk(cfs, executionController);
try
{
// Use a custom iterator instead of DataLimits to avoid stopping the original iterator
UnfilteredRowIterator toCacheIterator = new WrappingUnfilteredRowIterator(iter)
{
private int rowsCounted = 0;
@Override
public boolean hasNext()
{
return rowsCounted < rowsToCache && super.hasNext();
}
@Override
public Unfiltered next()
{
Unfiltered unfiltered = super.next();
if (unfiltered.isRow())
{
Row row = (Row) unfiltered;
if (row.hasLiveData(nowInSec(), enforceStrictLiveness))
rowsCounted++;
}
return unfiltered;
}
};
// We want to cache only rowsToCache rows
CachedPartition toCache = CachedBTreePartition.create(toCacheIterator, nowInSec());
if (sentinelSuccess && !toCache.isEmpty())
{
Tracing.trace("Caching {} rows", toCache.rowCount());
CacheService.instance.rowCache.replace(key, sentinel, toCache);
// Whether or not the previous replace has worked, our sentinel is not in the cache anymore
sentinelReplaced = true;
}
// We then re-filter out what this query wants.
// Note that in the case where we don't cache full partitions, it's possible that the current query is interested in more
// than what we've cached, so we can't just use toCache.
UnfilteredRowIterator cacheIterator = clusteringIndexFilter().getUnfilteredRowIterator(columnFilter(), toCache);
if (cacheFullPartitions)
{
// Everything is guaranteed to be in 'toCache', we're done with 'iter'
assert !iter.hasNext();
iter.close();
return cacheIterator;
}
return UnfilteredRowIterators.concat(cacheIterator, clusteringIndexFilter().filterNotIndexed(columnFilter(), iter));
}
catch (RuntimeException | Error e)
{
iter.close();
throw e;
}
}
finally
{
if (sentinelSuccess && !sentinelReplaced)
cfs.invalidateCachedPartition(key);
}
}
Tracing.trace("Fetching data but not populating cache as query does not query from the start of the partition");
return queryMemtableAndDisk(cfs, executionController);
}
/**
* Queries both memtable and sstables to fetch the result of this query.
*
* Please note that this method:
* 1) does not check the row cache.
* 2) does not apply the query limit, nor the row filter (and so ignore 2ndary indexes).
* Those are applied in {@link ReadCommand#executeLocally}.
* 3) does not record some of the read metrics (latency, scanned cells histograms) nor
* throws TombstoneOverwhelmingException.
* It is publicly exposed because there is a few places where that is exactly what we want,
* but it should be used only where you know you don't need thoses things.
*
* Also note that one must have created a {@code ReadExecutionController} on the queried table and we require it as
* a parameter to enforce that fact, even though it's not explicitlly used by the method.
*/
public UnfilteredRowIterator queryMemtableAndDisk(ColumnFamilyStore cfs, ReadExecutionController executionController)
{
assert executionController != null && executionController.validForReadOn(cfs);
Tracing.trace("Executing single-partition query on {}", cfs.name);
return queryMemtableAndDiskInternal(cfs, executionController);
}
private UnfilteredRowIterator queryMemtableAndDiskInternal(ColumnFamilyStore cfs, ReadExecutionController controller)
{
/*
* We have 2 main strategies:
* 1) We query memtables and sstables simulateneously. This is our most generic strategy and the one we use
* unless we have a names filter that we know we can optimize futher.
* 2) If we have a name filter (so we query specific rows), we can make a bet: that all column for all queried row
* will have data in the most recent sstable(s), thus saving us from reading older ones. This does imply we
* have a way to guarantee we have all the data for what is queried, which is only possible for name queries
* and if we have neither non-frozen collections/UDTs nor counters.
* If a non-frozen collection or UDT is queried we can't guarantee that an older sstable won't have some
* elements that weren't in the most recent sstables.
* Counters are intrinsically a collection of shards and so have the same problem.
* Counter tables are also special in the sense that their rows do not have primary key liveness
* as INSERT statements are not supported on counter tables. Due to that even if only the primary key
* columns where queried, querying SSTables in timestamp order will always be less efficient for counter tables.
* Also, if tracking repaired data then we skip this optimization so we can collate the repaired sstables
* and generate a digest over their merge, which procludes an early return.
*/
if (clusteringIndexFilter() instanceof ClusteringIndexNamesFilter
&& !metadata().isCounter()
&& !queriesMulticellType()
&& !controller.isTrackingRepairedStatus())
{
return queryMemtableAndSSTablesInTimestampOrder(cfs, (ClusteringIndexNamesFilter)clusteringIndexFilter(), controller);
}
Tracing.trace("Acquiring sstable references");
ColumnFamilyStore.ViewFragment view = cfs.select(View.select(SSTableSet.LIVE, partitionKey()));
view.sstables.sort(SSTableReader.maxTimestampDescending);
ClusteringIndexFilter filter = clusteringIndexFilter();
long minTimestamp = Long.MAX_VALUE;
long mostRecentPartitionTombstone = Long.MIN_VALUE;
InputCollector inputCollector = iteratorsForPartition(view, controller);
try
{
for (Memtable memtable : view.memtables)
{
Partition partition = memtable.getPartition(partitionKey());
if (partition == null)
continue;
minTimestamp = Math.min(minTimestamp, memtable.getMinTimestamp());
@SuppressWarnings("resource") // 'iter' is added to iterators which is closed on exception, or through the closing of the final merged iterator
UnfilteredRowIterator iter = filter.getUnfilteredRowIterator(columnFilter(), partition);
// Memtable data is always considered unrepaired
controller.updateMinOldestUnrepairedTombstone(partition.stats().minLocalDeletionTime);
inputCollector.addMemtableIterator(RTBoundValidator.validate(iter, RTBoundValidator.Stage.MEMTABLE, false));
mostRecentPartitionTombstone = Math.max(mostRecentPartitionTombstone,
iter.partitionLevelDeletion().markedForDeleteAt());
}
/*
* We can't eliminate full sstables based on the timestamp of what we've already read like
* in collectTimeOrderedData, but we still want to eliminate sstable whose maxTimestamp < mostRecentTombstone
* we've read. We still rely on the sstable ordering by maxTimestamp since if
* maxTimestamp_s1 < maxTimestamp_s0,
* we're guaranteed that s1 cannot have a row tombstone such that
* timestamp(tombstone) > maxTimestamp_s0
* since we necessarily have
* timestamp(tombstone) <= maxTimestamp_s1
* In other words, iterating in descending maxTimestamp order allow to do our mostRecentPartitionTombstone
* elimination in one pass, and minimize the number of sstables for which we read a partition tombstone.
*/
view.sstables.sort(SSTableReader.maxTimestampDescending);
int nonIntersectingSSTables = 0;
int includedDueToTombstones = 0;
SSTableReadMetricsCollector metricsCollector = new SSTableReadMetricsCollector();
if (controller.isTrackingRepairedStatus())
Tracing.trace("Collecting data from sstables and tracking repaired status");
for (SSTableReader sstable : view.sstables)
{
// if we've already seen a partition tombstone with a timestamp greater
// than the most recent update to this sstable, we can skip it
// if we're tracking repaired status, we mark the repaired digest inconclusive
// as other replicas may not have seen this partition delete and so could include
// data from this sstable (or others) in their digests
if (sstable.getMaxTimestamp() < mostRecentPartitionTombstone)
{
inputCollector.markInconclusive();
break;
}
if (shouldInclude(sstable))
{
if (!sstable.isRepaired())
controller.updateMinOldestUnrepairedTombstone(sstable.getMinLocalDeletionTime());
// 'iter' is added to iterators which is closed on exception, or through the closing of the final merged iterator
@SuppressWarnings("resource")
UnfilteredRowIteratorWithLowerBound iter = makeIterator(cfs, sstable, metricsCollector);
inputCollector.addSSTableIterator(sstable, iter);
mostRecentPartitionTombstone = Math.max(mostRecentPartitionTombstone,
iter.partitionLevelDeletion().markedForDeleteAt());
}
else
{
nonIntersectingSSTables++;
// sstable contains no tombstone if maxLocalDeletionTime == Integer.MAX_VALUE, so we can safely skip those entirely
if (sstable.mayHaveTombstones())
{
// 'iter' is added to iterators which is closed on exception, or through the closing of the final merged iterator
@SuppressWarnings("resource")
UnfilteredRowIteratorWithLowerBound iter = makeIterator(cfs, sstable, metricsCollector);
// if the sstable contains a partition delete, then we must include it regardless of whether it
// shadows any other data seen locally as we can't guarantee that other replicas have seen it
if (!iter.partitionLevelDeletion().isLive())
{
if (!sstable.isRepaired())
controller.updateMinOldestUnrepairedTombstone(sstable.getMinLocalDeletionTime());
inputCollector.addSSTableIterator(sstable, iter);
includedDueToTombstones++;
mostRecentPartitionTombstone = Math.max(mostRecentPartitionTombstone,
iter.partitionLevelDeletion().markedForDeleteAt());
}
else
{
iter.close();
}
}
}
}
if (Tracing.isTracing())
Tracing.trace("Skipped {}/{} non-slice-intersecting sstables, included {} due to tombstones",
nonIntersectingSSTables, view.sstables.size(), includedDueToTombstones);
if (inputCollector.isEmpty())
return EmptyIterators.unfilteredRow(cfs.metadata(), partitionKey(), filter.isReversed());
StorageHook.instance.reportRead(cfs.metadata().id, partitionKey());
List iterators = inputCollector.finalizeIterators(cfs, nowInSec(), controller.oldestUnrepairedTombstone());
return withSSTablesIterated(iterators, cfs.metric, metricsCollector);
}
catch (RuntimeException | Error e)
{
try
{
inputCollector.close();
}
catch (Exception e1)
{
e.addSuppressed(e1);
}
throw e;
}
}
private boolean shouldInclude(SSTableReader sstable)
{
// If some static columns are queried, we should always include the sstable: the clustering values stats of the sstable
// don't tell us if the sstable contains static values in particular.
// TODO: we could record if a sstable contains any static value at all.
if (!columnFilter().fetchedColumns().statics.isEmpty())
return true;
return clusteringIndexFilter().shouldInclude(sstable);
}
private UnfilteredRowIteratorWithLowerBound makeIterator(ColumnFamilyStore cfs,
SSTableReader sstable,
SSTableReadsListener listener)
{
return StorageHook.instance.makeRowIteratorWithLowerBound(cfs,
partitionKey(),
sstable,
clusteringIndexFilter(),
columnFilter(),
listener);
}
/**
* Return a wrapped iterator that when closed will update the sstables iterated and READ sample metrics.
* Note that we cannot use the Transformations framework because they greedily get the static row, which
* would cause all iterators to be initialized and hence all sstables to be accessed.
*/
@SuppressWarnings("resource")
private UnfilteredRowIterator withSSTablesIterated(List iterators,
TableMetrics metrics,
SSTableReadMetricsCollector metricsCollector)
{
@SuppressWarnings("resource") // Closed through the closing of the result of the caller method.
UnfilteredRowIterator merged = UnfilteredRowIterators.merge(iterators);
if (!merged.isEmpty())
{
DecoratedKey key = merged.partitionKey();
metrics.topReadPartitionFrequency.addSample(key.getKey(), 1);
}
class UpdateSstablesIterated extends Transformation
{
public void onPartitionClose()
{
int mergedSSTablesIterated = metricsCollector.getMergedSSTables();
metrics.updateSSTableIterated(mergedSSTablesIterated);
Tracing.trace("Merged data from memtables and {} sstables", mergedSSTablesIterated);
}
}
return Transformation.apply(merged, new UpdateSstablesIterated());
}
private boolean queriesMulticellType()
{
for (ColumnMetadata column : columnFilter().queriedColumns())
{
if (column.type.isMultiCell())
return true;
}
return false;
}
/**
* Do a read by querying the memtable(s) first, and then each relevant sstables sequentially by order of the sstable
* max timestamp.
*
* This is used for names query in the hope of only having to query the 1 or 2 most recent query and then knowing nothing
* more recent could be in the older sstables (which we can only guarantee if we know exactly which row we queries, and if
* no collection or counters are included).
* This method assumes the filter is a {@code ClusteringIndexNamesFilter}.
*/
private UnfilteredRowIterator queryMemtableAndSSTablesInTimestampOrder(ColumnFamilyStore cfs, ClusteringIndexNamesFilter filter, ReadExecutionController controller)
{
Tracing.trace("Acquiring sstable references");
ColumnFamilyStore.ViewFragment view = cfs.select(View.select(SSTableSet.LIVE, partitionKey()));
ImmutableBTreePartition result = null;
Tracing.trace("Merging memtable contents");
for (Memtable memtable : view.memtables)
{
Partition partition = memtable.getPartition(partitionKey());
if (partition == null)
continue;
try (UnfilteredRowIterator iter = filter.getUnfilteredRowIterator(columnFilter(), partition))
{
if (iter.isEmpty())
continue;
result = add(RTBoundValidator.validate(iter, RTBoundValidator.Stage.MEMTABLE, false),
result,
filter,
false,
controller);
}
}
/* add the SSTables on disk */
view.sstables.sort(SSTableReader.maxTimestampDescending);
// read sorted sstables
SSTableReadMetricsCollector metricsCollector = new SSTableReadMetricsCollector();
for (SSTableReader sstable : view.sstables)
{
// if we've already seen a partition tombstone with a timestamp greater
// than the most recent update to this sstable, we're done, since the rest of the sstables
// will also be older
if (result != null && sstable.getMaxTimestamp() < result.partitionLevelDeletion().markedForDeleteAt())
break;
long currentMaxTs = sstable.getMaxTimestamp();
filter = reduceFilter(filter, result, currentMaxTs);
if (filter == null)
break;
if (!shouldInclude(sstable))
{
// This mean that nothing queried by the filter can be in the sstable. One exception is the top-level partition deletion
// however: if it is set, it impacts everything and must be included. Getting that top-level partition deletion costs us
// some seek in general however (unless the partition is indexed and is in the key cache), so we first check if the sstable
// has any tombstone at all as a shortcut.
if (!sstable.mayHaveTombstones())
continue; // no tombstone at all, we can skip that sstable
// We need to get the partition deletion and include it if it's live. In any case though, we're done with that sstable.
try (UnfilteredRowIterator iter = StorageHook.instance.makeRowIterator(cfs,
sstable,
partitionKey(),
filter.getSlices(metadata()),
columnFilter(),
filter.isReversed(),
metricsCollector))
{
if (!iter.partitionLevelDeletion().isLive())
{
result = add(UnfilteredRowIterators.noRowsIterator(iter.metadata(),
iter.partitionKey(),
Rows.EMPTY_STATIC_ROW,
iter.partitionLevelDeletion(),
filter.isReversed()),
result,
filter,
sstable.isRepaired(),
controller);
}
else
{
result = add(RTBoundValidator.validate(iter, RTBoundValidator.Stage.SSTABLE, false),
result,
filter,
sstable.isRepaired(),
controller);
}
}
continue;
}
try (UnfilteredRowIterator iter = StorageHook.instance.makeRowIterator(cfs,
sstable,
partitionKey(),
filter.getSlices(metadata()),
columnFilter(),
filter.isReversed(),
metricsCollector))
{
if (iter.isEmpty())
continue;
result = add(RTBoundValidator.validate(iter, RTBoundValidator.Stage.SSTABLE, false),
result,
filter,
sstable.isRepaired(),
controller);
}
}
cfs.metric.updateSSTableIterated(metricsCollector.getMergedSSTables());
if (result == null || result.isEmpty())
return EmptyIterators.unfilteredRow(metadata(), partitionKey(), false);
DecoratedKey key = result.partitionKey();
cfs.metric.topReadPartitionFrequency.addSample(key.getKey(), 1);
StorageHook.instance.reportRead(cfs.metadata.id, partitionKey());
return result.unfilteredIterator(columnFilter(), Slices.ALL, clusteringIndexFilter().isReversed());
}
private ImmutableBTreePartition add(UnfilteredRowIterator iter, ImmutableBTreePartition result, ClusteringIndexNamesFilter filter, boolean isRepaired, ReadExecutionController controller)
{
if (!isRepaired)
controller.updateMinOldestUnrepairedTombstone(iter.stats().minLocalDeletionTime);
int maxRows = Math.max(filter.requestedRows().size(), 1);
if (result == null)
return ImmutableBTreePartition.create(iter, maxRows);
try (UnfilteredRowIterator merged = UnfilteredRowIterators.merge(Arrays.asList(iter, result.unfilteredIterator(columnFilter(), Slices.ALL, filter.isReversed()))))
{
return ImmutableBTreePartition.create(merged, maxRows);
}
}
private ClusteringIndexNamesFilter reduceFilter(ClusteringIndexNamesFilter filter, Partition result, long sstableTimestamp)
{
if (result == null)
return filter;
// According to the CQL semantics a row exists if at least one of its columns is not null (including the primary key columns).
// Having the queried columns not null is unfortunately not enough to prove that a row exists as some column deletion
// for the queried columns can exist on another node.
// For CQL tables it is enough to have the primary key liveness and the queried columns as the primary key liveness prove that
// the row exists even if all the other columns are deleted.
// COMPACT tables do not have primary key liveness and by consequence we are forced to get all the fetched columns to ensure that
// we can return the correct result if the queried columns are deleted on another node but one of the non-queried columns is not.
RegularAndStaticColumns columns = metadata().isCompactTable() ? columnFilter().fetchedColumns() : columnFilter().queriedColumns();
NavigableSet> clusterings = filter.requestedRows();
// We want to remove rows for which we have values for all requested columns. We have to deal with both static and regular rows.
boolean removeStatic = false;
if (!columns.statics.isEmpty())
{
Row staticRow = result.getRow(Clustering.STATIC_CLUSTERING);
removeStatic = staticRow != null && isRowComplete(staticRow, columns.statics, sstableTimestamp);
}
NavigableSet> toRemove = null;
try (UnfilteredRowIterator iterator = result.unfilteredIterator(columnFilter(), clusterings, false))
{
while (iterator.hasNext())
{
Unfiltered unfiltered = iterator.next();
if (unfiltered == null || !unfiltered.isRow())
continue;
Row row = (Row) unfiltered;
if (!isRowComplete(row, columns.regulars, sstableTimestamp))
continue;
if (toRemove == null)
toRemove = new TreeSet<>(result.metadata().comparator);
toRemove.add(row.clustering());
}
}
if (!removeStatic && toRemove == null)
return filter;
// Check if we have everything we need
boolean hasNoMoreStatic = columns.statics.isEmpty() || removeStatic;
boolean hasNoMoreClusterings = clusterings.isEmpty() || (toRemove != null && toRemove.size() == clusterings.size());
if (hasNoMoreStatic && hasNoMoreClusterings)
return null;
if (toRemove != null)
{
BTreeSet.Builder> newClusterings = BTreeSet.builder(result.metadata().comparator);
newClusterings.addAll(Sets.difference(clusterings, toRemove));
clusterings = newClusterings.build();
}
return new ClusteringIndexNamesFilter(clusterings, filter.isReversed());
}
/**
* We can stop reading row data from disk if what we've already read is more recent than the max timestamp
* of the next newest SSTable that might have data for the query. We care about 1.) the row timestamp (since
* every query cares if the row exists or not), 2.) the timestamps of the requested cells, and 3.) whether or
* not any of the cells we've read have actual data.
*
* @param row a potentially incomplete {@link Row}
* @param requestedColumns the columns requested by the query
* @param sstableTimestamp the max timestamp of the next newest SSTable to read
*
* @return true if the supplied {@link Row} is complete and its data more recent than the supplied timestamp
*/
private boolean isRowComplete(Row row, Columns requestedColumns, long sstableTimestamp)
{
// Note that compact tables will always have an empty primary key liveness info.
if (!metadata().isCompactTable() && (row.primaryKeyLivenessInfo().isEmpty() || row.primaryKeyLivenessInfo().timestamp() <= sstableTimestamp))
return false;
for (ColumnMetadata column : requestedColumns)
{
Cell cell = row.getCell(column);
if (cell == null || cell.timestamp() <= sstableTimestamp)
return false;
}
return true;
}
@Override
public boolean selectsFullPartition()
{
if (metadata().isStaticCompactTable())
return true;
return clusteringIndexFilter.selectsAllPartition() && !rowFilter().hasExpressionOnClusteringOrRegularColumns();
}
@Override
public String toString()
{
return String.format("Read(%s columns=%s rowFilter=%s limits=%s key=%s filter=%s, nowInSec=%d)",
metadata().toString(),
columnFilter(),
rowFilter(),
limits(),
metadata().partitionKeyType.getString(partitionKey().getKey()),
clusteringIndexFilter.toString(metadata()),
nowInSec());
}
@Override
public Verb verb()
{
return Verb.READ_REQ;
}
protected void appendCQLWhereClause(StringBuilder sb)
{
sb.append(" WHERE ");
sb.append(ColumnMetadata.toCQLString(metadata().partitionKeyColumns())).append(" = ");
DataRange.appendKeyString(sb, metadata().partitionKeyType, partitionKey().getKey());
// We put the row filter first because the clustering index filter can end by "ORDER BY"
if (!rowFilter().isEmpty())
sb.append(" AND ").append(rowFilter());
String filterString = clusteringIndexFilter().toCQLString(metadata());
if (!filterString.isEmpty())
sb.append(" AND ").append(filterString);
}
protected void serializeSelection(DataOutputPlus out, int version) throws IOException
{
metadata().partitionKeyType.writeValue(partitionKey().getKey(), out);
ClusteringIndexFilter.serializer.serialize(clusteringIndexFilter(), out, version);
}
protected long selectionSerializedSize(int version)
{
return metadata().partitionKeyType.writtenLength(partitionKey().getKey())
+ ClusteringIndexFilter.serializer.serializedSize(clusteringIndexFilter(), version);
}
public boolean isLimitedToOnePartition()
{
return true;
}
public boolean isRangeRequest()
{
return false;
}
/**
* Groups multiple single partition read commands.
*/
public static class Group extends SinglePartitionReadQuery.Group
{
public static Group create(TableMetadata metadata,
int nowInSec,
ColumnFilter columnFilter,
RowFilter rowFilter,
DataLimits limits,
List partitionKeys,
ClusteringIndexFilter clusteringIndexFilter)
{
List commands = new ArrayList<>(partitionKeys.size());
for (DecoratedKey partitionKey : partitionKeys)
{
commands.add(SinglePartitionReadCommand.create(metadata,
nowInSec,
columnFilter,
rowFilter,
limits,
partitionKey,
clusteringIndexFilter));
}
return new Group(commands, limits);
}
public Group(List commands, DataLimits limits)
{
super(commands, limits);
}
public static Group one(SinglePartitionReadCommand command)
{
return new Group(Collections.singletonList(command), command.limits());
}
public PartitionIterator execute(ConsistencyLevel consistency, ClientState clientState, long queryStartNanoTime) throws RequestExecutionException
{
return StorageProxy.read(this, consistency, clientState, queryStartNanoTime);
}
}
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
{
DecoratedKey key = metadata.partitioner.decorateKey(metadata.partitionKeyType.readBuffer(in, DatabaseDescriptor.getMaxValueSize()));
ClusteringIndexFilter filter = ClusteringIndexFilter.serializer.deserialize(in, version, metadata);
return new SinglePartitionReadCommand(isDigest, digestVersion, acceptsTransient, metadata, nowInSec, columnFilter, rowFilter, limits, key, filter, index);
}
}
/**
* {@code SSTableReaderListener} used to collect metrics about SSTable read access.
*/
private static final class SSTableReadMetricsCollector implements SSTableReadsListener
{
/**
* The number of SSTables that need to be merged. This counter is only updated for single partition queries
* since this has been the behavior so far.
*/
private int mergedSSTables;
@Override
public void onSSTableSelected(SSTableReader sstable, RowIndexEntry indexEntry, SelectionReason reason)
{
sstable.incrementReadCount();
mergedSSTables++;
}
/**
* Returns the number of SSTables that need to be merged.
* @return the number of SSTables that need to be merged.
*/
public int getMergedSSTables()
{
return mergedSSTables;
}
}
}