Package org.apache.cassandra.io.sstable.format.bti

Class PartitionIndex

java.lang.Object

org.apache.cassandra.io.sstable.format.bti.PartitionIndex

All Implemented Interfaces:

AutoCloseable, SharedCloseable

public class PartitionIndex
extends Object
implements SharedCloseable

This class holds the partition index as an on-disk trie mapping unique prefixes of decorated keys to:

• data file position if the partition is small enough to not need an index
• row index file position if the partition has a row index

plus

• the last 8 bits of the key's filter hash which is used to filter out mismatched keys without reading the key

To avoid having to create an object to carry the result, the two are distinguished by sign. Direct-to-dfile entries are recorded as ~position (~ instead of - to differentiate 0 in ifile from 0 in dfile).

In either case the contents of the file at this position start with a serialization of the key which can be used to verify the correct key is found.

The indexes are created by PartitionIndexBuilder. To read the index one must obtain a thread-unsafe PartitionIndex.Reader or PartitionIndex.IndexPosIterator.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	PartitionIndex.Acceptor<ArgType,ResultType>
static class	PartitionIndex.IndexPosIterator	Iterator of index positions covered between two keys.
static class	PartitionIndex.Reader	Provides methods to read the partition index trie.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	FOOTER_LENGTH
static final long	NOT_FOUND

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	PartitionIndex(PartitionIndex src)
	PartitionIndex(FileHandle fh, long trieRoot, long keyCount, DecoratedKey first, DecoratedKey last)

Method Summary

Modifier and Type	Method	Description
void	addTo(Ref.IdentityCollection identities)
protected PartitionIndex.IndexPosIterator	allKeysIterator()
void	close()
Throwable	close(Throwable accumulate)
void	dumpTrie(String fileName)	debug/test code
DecoratedKey	firstKey()
protected Rebufferer	instantiateRebufferer()
DecoratedKey	lastKey()
static PartitionIndex	load(FileHandle.Builder fhBuilder, IPartitioner partitioner, boolean preload)
static PartitionIndex	load(FileHandle fh, IPartitioner partitioner, boolean preload)
PartitionIndex.Reader	openReader()
static Pair<DecoratedKey,DecoratedKey>	readFirstAndLastKey(File file, IPartitioner partitioner)
PartitionIndex	sharedCopy()
long	size()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

NOT_FOUND

public static final long NOT_FOUND

See Also:

• Constant Field Values

FOOTER_LENGTH

public static final int FOOTER_LENGTH

See Also:

• Constant Field Values

Constructor Details

PartitionIndex

public PartitionIndex(FileHandle fh,
 long trieRoot,
 long keyCount,
 DecoratedKey first,
 DecoratedKey last)

PartitionIndex

protected PartitionIndex(PartitionIndex src)

Method Details

size

public long size()

firstKey

public DecoratedKey firstKey()

lastKey

public DecoratedKey lastKey()

sharedCopy

public PartitionIndex sharedCopy()

Specified by:

sharedCopy in interface SharedCloseable

Returns:

a new instance of the object representing the same state and backed by the same underlying resources. Coordinates with the original (and other instances) when the underlying resource should be closed. Throws an exception if the shared resource has already been closed.

addTo

public void addTo(Ref.IdentityCollection identities)

Specified by:

addTo in interface SharedCloseable

load

public static PartitionIndex load(FileHandle.Builder fhBuilder,
 IPartitioner partitioner,
 boolean preload)
                           throws IOException

Throws:

IOException

readFirstAndLastKey

public static Pair<DecoratedKey,DecoratedKey> readFirstAndLastKey(File file,
 IPartitioner partitioner)
                                                           throws IOException

Throws:

IOException

load

public static PartitionIndex load(FileHandle fh,
 IPartitioner partitioner,
 boolean preload)
                           throws IOException

Throws:

IOException

close

public void close()

Specified by:

close in interface AutoCloseable

close

public Throwable close(Throwable accumulate)

Specified by:

close in interface SharedCloseable

openReader

public PartitionIndex.Reader openReader()

allKeysIterator

protected PartitionIndex.IndexPosIterator allKeysIterator()

instantiateRebufferer

protected Rebufferer instantiateRebufferer()

dumpTrie

public void dumpTrie(String fileName)

debug/test code