org.apache.cassandra.db.index.keys.KeysSearcher Maven / Gradle / Ivy
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.cassandra.db.index.keys;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.db.*;
import org.apache.cassandra.db.filter.ExtendedFilter;
import org.apache.cassandra.db.filter.IDiskAtomFilter;
import org.apache.cassandra.db.filter.QueryFilter;
import org.apache.cassandra.db.index.*;
import org.apache.cassandra.dht.AbstractBounds;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.thrift.IndexExpression;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.HeapAllocator;
public class KeysSearcher extends SecondaryIndexSearcher
{
private static final Logger logger = LoggerFactory.getLogger(KeysSearcher.class);
public KeysSearcher(SecondaryIndexManager indexManager, Set columns)
{
super(indexManager, columns);
}
@Override
public List search(ExtendedFilter filter)
{
assert filter.getClause() != null && !filter.getClause().isEmpty();
return baseCfs.filter(getIndexedIterator(filter), filter);
}
private ColumnFamilyStore.AbstractScanIterator getIndexedIterator(final ExtendedFilter filter)
{
// Start with the most-restrictive indexed clause, then apply remaining clauses
// to each row matching that clause.
// TODO: allow merge join instead of just one index + loop
final IndexExpression primary = highestSelectivityPredicate(filter.getClause());
final SecondaryIndex index = indexManager.getIndexForColumn(primary.column_name);
assert index != null;
assert index.getIndexCfs() != null;
final DecoratedKey indexKey = index.getIndexKeyFor(primary.value);
if (logger.isDebugEnabled())
logger.debug("Most-selective indexed predicate is {}",
((AbstractSimplePerColumnSecondaryIndex) index).expressionString(primary));
/*
* XXX: If the range requested is a token range, we'll have to start at the beginning (and stop at the end) of
* the indexed row unfortunately (which will be inefficient), because we have not way to intuit the small
* possible key having a given token. A fix would be to actually store the token along the key in the
* indexed row.
*/
final AbstractBounds range = filter.dataRange.keyRange();
final ByteBuffer startKey = range.left instanceof DecoratedKey ? ((DecoratedKey)range.left).key : ByteBufferUtil.EMPTY_BYTE_BUFFER;
final ByteBuffer endKey = range.right instanceof DecoratedKey ? ((DecoratedKey)range.right).key : ByteBufferUtil.EMPTY_BYTE_BUFFER;
return new ColumnFamilyStore.AbstractScanIterator()
{
private ByteBuffer lastSeenKey = startKey;
private Iterator indexColumns;
private int columnsRead = Integer.MAX_VALUE;
protected Row computeNext()
{
int meanColumns = Math.max(index.getIndexCfs().getMeanColumns(), 1);
// We shouldn't fetch only 1 row as this provides buggy paging in case the first row doesn't satisfy all clauses
int rowsPerQuery = Math.max(Math.min(filter.maxRows(), filter.maxColumns() / meanColumns), 2);
while (true)
{
if (indexColumns == null || !indexColumns.hasNext())
{
if (columnsRead < rowsPerQuery)
{
logger.trace("Read only {} (< {}) last page through, must be done", columnsRead, rowsPerQuery);
return endOfData();
}
if (logger.isTraceEnabled() && (index instanceof AbstractSimplePerColumnSecondaryIndex))
logger.trace("Scanning index {} starting with {}",
((AbstractSimplePerColumnSecondaryIndex)index).expressionString(primary), index.getBaseCfs().metadata.getKeyValidator().getString(startKey));
QueryFilter indexFilter = QueryFilter.getSliceFilter(indexKey,
index.getIndexCfs().name,
lastSeenKey,
endKey,
false,
rowsPerQuery,
filter.timestamp);
ColumnFamily indexRow = index.getIndexCfs().getColumnFamily(indexFilter);
logger.trace("fetched {}", indexRow);
if (indexRow == null)
{
logger.trace("no data, all done");
return endOfData();
}
Collection sortedColumns = indexRow.getSortedColumns();
columnsRead = sortedColumns.size();
indexColumns = sortedColumns.iterator();
Column firstColumn = sortedColumns.iterator().next();
// Paging is racy, so it is possible the first column of a page is not the last seen one.
if (lastSeenKey != startKey && lastSeenKey.equals(firstColumn.name()))
{
// skip the row we already saw w/ the last page of results
indexColumns.next();
logger.trace("Skipping {}", baseCfs.metadata.getKeyValidator().getString(firstColumn.name()));
}
else if (range instanceof Range && indexColumns.hasNext() && firstColumn.name().equals(startKey))
{
// skip key excluded by range
indexColumns.next();
logger.trace("Skipping first key as range excludes it");
}
}
while (indexColumns.hasNext())
{
Column column = indexColumns.next();
lastSeenKey = column.name();
if (column.isMarkedForDelete(filter.timestamp))
{
logger.trace("skipping {}", column.name());
continue;
}
DecoratedKey dk = baseCfs.partitioner.decorateKey(lastSeenKey);
if (!range.right.isMinimum(baseCfs.partitioner) && range.right.compareTo(dk) < 0)
{
logger.trace("Reached end of assigned scan range");
return endOfData();
}
if (!range.contains(dk))
{
logger.trace("Skipping entry {} outside of assigned scan range", dk.token);
continue;
}
logger.trace("Returning index hit for {}", dk);
ColumnFamily data = baseCfs.getColumnFamily(new QueryFilter(dk, baseCfs.name, filter.columnFilter(lastSeenKey), filter.timestamp));
// While the column family we'll get in the end should contains the primary clause column, the initialFilter may not have found it and can thus be null
if (data == null)
data = TreeMapBackedSortedColumns.factory.create(baseCfs.metadata);
// as in CFS.filter - extend the filter to ensure we include the columns
// from the index expressions, just in case they weren't included in the initialFilter
IDiskAtomFilter extraFilter = filter.getExtraFilter(dk, data);
if (extraFilter != null)
{
ColumnFamily cf = baseCfs.getColumnFamily(new QueryFilter(dk, baseCfs.name, extraFilter, filter.timestamp));
if (cf != null)
data.addAll(cf, HeapAllocator.instance);
}
if (((KeysIndex)index).isIndexEntryStale(indexKey.key, data, filter.timestamp))
{
// delete the index entry w/ its own timestamp
Column dummyColumn = new Column(primary.column_name, indexKey.key, column.timestamp());
((PerColumnSecondaryIndex)index).delete(dk.key, dummyColumn);
continue;
}
return new Row(dk, data);
}
}
}
public void close() throws IOException {}
};
}
}
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