public class RowIndexEntry<T> extends java.lang.Object implements IMeasurableMemory
RowIndexEntry is defined as follows:
(long) position (64 bit long, vint encoded)
(int) serialized size of data that follows (32 bit int, vint encoded)
-- following for indexed entries only (so serialized size > 0)
(int) DeletionTime.localDeletionTime
(long) DeletionTime.markedForDeletionAt
(int) number of IndexInfo objects (32 bit int, vint encoded)
(*) serialized IndexInfo objects, see below
(*) offsets of serialized IndexInfo objects, since version "ma" (3.0)
Each IndexInfo object's offset is relative to the first IndexInfo object.
See IndexInfo for a description of the serialized format.
For each partition, the layout of the index file looks like this:
short lengthRowIndexEntry objects
Generally, we distinguish between index entries that have index
samples (list of IndexInfo objects) and those who don't.
For each portion of data for a single partition in the data file,
an index sample is created. The size of that portion is defined
by Config.column_index_size_in_kb.
Index entries with less than 2 index samples, will just store the position in the data file.
Note: legacy sstables for index entries are those sstable formats that
do not have an offsets table to index samples (IndexInfo
objects). These are those sstables created on Cassandra versions
earlier than 3.0.
For index entries with index samples we store the index samples
(IndexInfo objects). The bigger the partition, the more
index samples are created. Since a huge amount of index samples
will "pollute" the heap and cause huge GC pressure, Cassandra 3.6
(CASSANDRA-11206) distinguishes between index entries with an
"acceptable" amount of index samples per partition and those
with an "enormous" amount of index samples. The barrier
is controlled by the configuration parameter
Config.column_index_cache_size_in_kb.
Index entries with a total serialized size of index samples up to
column_index_cache_size_in_kb will be held in an array.
Index entries exceeding that value will always be accessed from
disk.
This results in these classes:
RowIndexEntry just stores the offset in the data file.IndexedEntry is for index entries with index samples
and used for both current and legacy sstables, which do not exceed
Config.column_index_cache_size_in_kb.ShallowIndexedEntry is for index entries with index samples
that exceed Config.column_index_cache_size_in_kb
for sstables with an offset table to the index samples.LegacyShallowIndexedEntry is for index entries with index samples
that exceed Config.column_index_cache_size_in_kb
but for legacy sstables.
Since access to index samples on disk (obviously) requires some file
reader, that functionality is encapsulated in implementations of
RowIndexEntry.IndexInfoRetriever. There is an implementation to access
index samples of legacy sstables (without the offsets table),
an implementation of access sstables with an offsets table.
Until now (Cassandra 3.x), we still support reading from legacy sstables -
i.e. sstables created by Cassandra < 3.0 (see BigFormat.
| Modifier and Type | Class and Description |
|---|---|
static interface |
RowIndexEntry.IndexInfoRetriever
Base class to access
IndexInfo objects. |
static interface |
RowIndexEntry.IndexSerializer<T> |
static class |
RowIndexEntry.Serializer |
| Modifier and Type | Field and Description |
|---|---|
long |
position |
| Constructor and Description |
|---|
RowIndexEntry(long position) |
| Modifier and Type | Method and Description |
|---|---|
int |
columnsIndexCount() |
static RowIndexEntry<IndexInfo> |
create(long dataFilePosition,
long indexFilePosition,
DeletionTime deletionTime,
long headerLength,
int columnIndexCount,
int indexedPartSize,
java.util.List<IndexInfo> indexSamples,
int[] offsets,
ISerializer<IndexInfo> idxInfoSerializer) |
DeletionTime |
deletionTime() |
long |
headerLength()
The length of the row header (partition key, partition deletion and static row).
|
boolean |
indexOnHeap() |
boolean |
isIndexed() |
RowIndexEntry.IndexInfoRetriever |
openWithIndex(FileHandle indexFile) |
void |
serialize(DataOutputPlus out,
IndexInfo.Serializer idxInfoSerializer,
java.nio.ByteBuffer indexInfo) |
void |
serializeForCache(DataOutputPlus out) |
long |
unsharedHeapSize() |
public boolean isIndexed()
public boolean indexOnHeap()
public DeletionTime deletionTime()
public long headerLength()
UnsupportedOperationException if !isIndexed().public int columnsIndexCount()
public long unsharedHeapSize()
unsharedHeapSize in interface IMeasurableMemorypublic static RowIndexEntry<IndexInfo> create(long dataFilePosition, long indexFilePosition, DeletionTime deletionTime, long headerLength, int columnIndexCount, int indexedPartSize, java.util.List<IndexInfo> indexSamples, int[] offsets, ISerializer<IndexInfo> idxInfoSerializer)
dataFilePosition - position of the partition in the Component.Type.DATA fileindexFilePosition - position in the Component.Type.PRIMARY_INDEX of the RowIndexEntrydeletionTime - deletion time of RowIndexEntryheaderLength - deletion time of RowIndexEntrycolumnIndexCount - number of IndexInfo entries in the RowIndexEntryindexedPartSize - serialized size of all serialized IndexInfo objects and their offsetsindexSamples - list with IndexInfo offsets (if total serialized size is less than Config.column_index_cache_size_in_kboffsets - offsets of IndexInfo offsetsidxInfoSerializer - the IndexInfo serializerpublic RowIndexEntry.IndexInfoRetriever openWithIndex(FileHandle indexFile)
public void serialize(DataOutputPlus out, IndexInfo.Serializer idxInfoSerializer, java.nio.ByteBuffer indexInfo) throws java.io.IOException
java.io.IOExceptionpublic void serializeForCache(DataOutputPlus out) throws java.io.IOException
java.io.IOExceptionCopyright © 2018 The Apache Software Foundation