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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.
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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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* Unless required by applicable law or agreed to in writing, software
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package org.apache.cassandra.index.internal.composites;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import org.apache.cassandra.schema.TableMetadata;
import org.apache.cassandra.db.*;
import org.apache.cassandra.db.filter.ClusteringIndexNamesFilter;
import org.apache.cassandra.db.filter.ClusteringIndexSliceFilter;
import org.apache.cassandra.db.filter.DataLimits;
import org.apache.cassandra.db.filter.RowFilter;
import org.apache.cassandra.db.partitions.UnfilteredPartitionIterator;
import org.apache.cassandra.db.rows.*;
import org.apache.cassandra.db.transform.Transformation;
import org.apache.cassandra.index.internal.CassandraIndex;
import org.apache.cassandra.index.internal.CassandraIndexSearcher;
import org.apache.cassandra.index.internal.IndexEntry;
import org.apache.cassandra.utils.btree.BTreeSet;
import org.apache.cassandra.utils.concurrent.OpOrder;
public class CompositesSearcher extends CassandraIndexSearcher
{
public CompositesSearcher(ReadCommand command,
RowFilter.Expression expression,
CassandraIndex index)
{
super(command, expression, index);
}
private boolean isMatchingEntry(DecoratedKey partitionKey, IndexEntry entry, ReadCommand command)
{
return command.selectsKey(partitionKey) && command.selectsClustering(partitionKey, entry.indexedEntryClustering);
}
private boolean isStaticColumn()
{
return index.getIndexedColumn().isStatic();
}
protected UnfilteredPartitionIterator queryDataFromIndex(final DecoratedKey indexKey,
final RowIterator indexHits,
final ReadCommand command,
final ReadExecutionController executionController)
{
assert indexHits.staticRow() == Rows.EMPTY_STATIC_ROW;
return new UnfilteredPartitionIterator()
{
private IndexEntry nextEntry;
private UnfilteredRowIterator next;
public TableMetadata metadata()
{
return command.metadata();
}
public boolean hasNext()
{
return prepareNext();
}
public UnfilteredRowIterator next()
{
if (next == null)
prepareNext();
UnfilteredRowIterator toReturn = next;
next = null;
return toReturn;
}
private boolean prepareNext()
{
while (true)
{
if (next != null)
return true;
if (nextEntry == null)
{
if (!indexHits.hasNext())
return false;
nextEntry = index.decodeEntry(indexKey, indexHits.next());
}
SinglePartitionReadCommand dataCmd;
DecoratedKey partitionKey = index.baseCfs.decorateKey(nextEntry.indexedKey);
List entries = new ArrayList<>();
if (isStaticColumn())
{
// The index hit may not match the commad key constraint
if (!isMatchingEntry(partitionKey, nextEntry, command)) {
nextEntry = indexHits.hasNext() ? index.decodeEntry(indexKey, indexHits.next()) : null;
continue;
}
// If the index is on a static column, we just need to do a full read on the partition.
// Note that we want to re-use the command.columnFilter() in case of future change.
dataCmd = SinglePartitionReadCommand.create(index.baseCfs.metadata(),
command.nowInSec(),
command.columnFilter(),
RowFilter.NONE,
DataLimits.NONE,
partitionKey,
command.clusteringIndexFilter(partitionKey));
entries.add(nextEntry);
nextEntry = indexHits.hasNext() ? index.decodeEntry(indexKey, indexHits.next()) : null;
}
else
{
// Gather all index hits belonging to the same partition and query the data for those hits.
// TODO: it's much more efficient to do 1 read for all hits to the same partition than doing
// 1 read per index hit. However, this basically mean materializing all hits for a partition
// in memory so we should consider adding some paging mechanism. However, index hits should
// be relatively small so it's much better than the previous code that was materializing all
// *data* for a given partition.
BTreeSet.Builder> clusterings = BTreeSet.builder(index.baseCfs.getComparator());
while (nextEntry != null && partitionKey.getKey().equals(nextEntry.indexedKey))
{
// We're queried a slice of the index, but some hits may not match some of the clustering column constraints
if (isMatchingEntry(partitionKey, nextEntry, command))
{
clusterings.add(nextEntry.indexedEntryClustering);
entries.add(nextEntry);
}
nextEntry = indexHits.hasNext() ? index.decodeEntry(indexKey, indexHits.next()) : null;
}
// Because we've eliminated entries that don't match the clustering columns, it's possible we added nothing
if (clusterings.isEmpty())
continue;
// Query the gathered index hits. We still need to filter stale hits from the resulting query.
ClusteringIndexNamesFilter filter = new ClusteringIndexNamesFilter(clusterings.build(), false);
dataCmd = SinglePartitionReadCommand.create(index.baseCfs.metadata(),
command.nowInSec(),
command.columnFilter(),
command.rowFilter(),
DataLimits.NONE,
partitionKey,
filter,
null);
}
@SuppressWarnings("resource") // We close right away if empty, and if it's assign to next it will be called either
// by the next caller of next, or through closing this iterator is this come before.
UnfilteredRowIterator dataIter =
filterStaleEntries(dataCmd.queryMemtableAndDisk(index.baseCfs, executionController),
indexKey.getKey(),
entries,
executionController.getWriteContext(),
command.nowInSec());
if (dataIter.isEmpty())
{
dataIter.close();
continue;
}
next = dataIter;
return true;
}
}
public void remove()
{
throw new UnsupportedOperationException();
}
public void close()
{
indexHits.close();
if (next != null)
next.close();
}
};
}
private void deleteAllEntries(final List entries, final WriteContext ctx, final int nowInSec)
{
entries.forEach(entry ->
index.deleteStaleEntry(entry.indexValue,
entry.indexClustering,
new DeletionTime(entry.timestamp, nowInSec),
ctx));
}
// We assume all rows in dataIter belong to the same partition.
@SuppressWarnings("resource")
private UnfilteredRowIterator filterStaleEntries(UnfilteredRowIterator dataIter,
final ByteBuffer indexValue,
final List entries,
final WriteContext ctx,
final int nowInSec)
{
// collect stale index entries and delete them when we close this iterator
final List staleEntries = new ArrayList<>();
// if there is a partition level delete in the base table, we need to filter
// any index entries which would be shadowed by it
if (!dataIter.partitionLevelDeletion().isLive())
{
DeletionTime deletion = dataIter.partitionLevelDeletion();
entries.forEach(e -> {
if (deletion.deletes(e.timestamp))
staleEntries.add(e);
});
}
UnfilteredRowIterator iteratorToReturn = null;
if (isStaticColumn())
{
if (entries.size() != 1)
throw new AssertionError("A partition should have at most one index within a static column index");
iteratorToReturn = dataIter;
if (index.isStale(dataIter.staticRow(), indexValue, nowInSec))
{
// The entry is staled, we return no rows in this partition.
staleEntries.addAll(entries);
iteratorToReturn = UnfilteredRowIterators.noRowsIterator(dataIter.metadata(),
dataIter.partitionKey(),
Rows.EMPTY_STATIC_ROW,
dataIter.partitionLevelDeletion(),
dataIter.isReverseOrder());
}
deleteAllEntries(staleEntries, ctx, nowInSec);
}
else
{
ClusteringComparator comparator = dataIter.metadata().comparator;
class Transform extends Transformation
{
private int entriesIdx;
@Override
public Row applyToRow(Row row)
{
IndexEntry entry = findEntry(row.clustering());
if (!index.isStale(row, indexValue, nowInSec))
return row;
staleEntries.add(entry);
return null;
}
private IndexEntry findEntry(Clustering clustering)
{
assert entriesIdx < entries.size();
while (entriesIdx < entries.size())
{
IndexEntry entry = entries.get(entriesIdx++);
Clustering indexedEntryClustering = entry.indexedEntryClustering;
// The entries are in clustering order. So that the requested entry should be the
// next entry, the one at 'entriesIdx'. However, we can have stale entries, entries
// that have no corresponding row in the base table typically because of a range
// tombstone or partition level deletion. Delete such stale entries.
// For static column, we only need to compare the partition key, otherwise we compare
// the whole clustering.
int cmp = comparator.compare(indexedEntryClustering, clustering);
assert cmp <= 0; // this would means entries are not in clustering order, which shouldn't happen
if (cmp == 0)
return entry;
// COMPACT COMPOSITE tables support null values in there clustering key but
// those tables do not support static columns. By consequence if a table
// has some static columns and all its clustering key elements are null
// it means that the partition exists and contains only static data
if (!dataIter.metadata().hasStaticColumns() || !containsOnlyNullValues(indexedEntryClustering))
staleEntries.add(entry);
}
// entries correspond to the rows we've queried, so we shouldn't have a row that has no corresponding entry.
throw new AssertionError();
}
private boolean containsOnlyNullValues(Clustering indexedEntryClustering)
{
int i = 0;
for (; i < indexedEntryClustering.size() && indexedEntryClustering.get(i) == null; i++);
return i == indexedEntryClustering.size();
}
@Override
public void onPartitionClose()
{
deleteAllEntries(staleEntries, ctx, nowInSec);
}
}
iteratorToReturn = Transformation.apply(dataIter, new Transform());
}
return iteratorToReturn;
}
}
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