Package org.apache.cassandra.db.memtable

Class ShardedSkipListMemtable

java.lang.Object
org.apache.cassandra.db.memtable.AbstractMemtable
org.apache.cassandra.db.memtable.AbstractMemtableWithCommitlog
org.apache.cassandra.db.memtable.AbstractAllocatorMemtable
org.apache.cassandra.db.memtable.AbstractShardedMemtable
org.apache.cassandra.db.memtable.ShardedSkipListMemtable
All Implemented Interfaces:
Comparable<Memtable>, CellSourceIdentifier, Memtable, UnfilteredSource
public class ShardedSkipListMemtable extends AbstractShardedMemtable
A proof-of-concept sharded memtable implementation. This implementation splits the partition skip-list into several independent skip-lists each covering a roughly equal part of the token space served by this node. This reduces congestion of the skip-list from concurrent writes and can lead to improved write throughput. The implementation takes two parameters: - shards: the number of shards to split into. - serialize_writes: if false, each shard may serve multiple writes in parallel; if true, writes to each shard are synchronized. Also see Memtable_API.md.

  • Field Details

  • Method Details

    • isClean

      public boolean isClean()
      Description copied from interface: Memtable
      True if the memtable contains no data

    • put

      public long put(PartitionUpdate update, UpdateTransaction indexer, OpOrder.Group opGroup)
      Should only be called by ColumnFamilyStore.apply via Keyspace.apply, which supplies the appropriate OpOrdering. commitLogSegmentPosition should only be null if this is a secondary index, in which case it is *expected* to be null
      Parameters:
      update - the partition update, may be a new partition or an update to an existing one
      indexer - receives information about the update's effect
      opGroup - write operation group, used to permit the operation to complete if it is needed to complete a flush to free space.
      Returns:
      the smallest timestamp delta between corresponding rows from existing and update. A timestamp delta being computed as the difference between the cells and DeletionTimes from any existing partition and those in update. See CASSANDRA-7979.

    • getLiveDataSize

      public long getLiveDataSize()
      Technically we should scatter gather on all the core threads because the size in following calls are not using volatile variables, but for metrics purpose this should be good enough.

    • operationCount

      public long operationCount()
      Description copied from interface: Memtable
      Number of "operations" (in the sense defined in PartitionUpdate.operationCount()) the memtable has executed.
      Specified by:
      operationCount in interface Memtable
      Overrides:
      operationCount in class AbstractMemtable

    • partitionCount

      public long partitionCount()
      Description copied from interface: Memtable
      Number of partitions stored in the memtable

    • getMinTimestamp

      public long getMinTimestamp()
      Returns the minTS if one available, otherwise NO_MIN_TIMESTAMP. EncodingStats uses a synthetic epoch TS at 2015. We don't want to leak that (CASSANDRA-18118) so we return NO_MIN_TIMESTAMP instead.
      Specified by:
      getMinTimestamp in interface UnfilteredSource
      Overrides:
      getMinTimestamp in class AbstractMemtable
      Returns:
      The minTS or NO_MIN_TIMESTAMP if none available

    • getMinLocalDeletionTime

      public long getMinLocalDeletionTime()
      Description copied from interface: UnfilteredSource
      Minimum local deletion time in the memtable
      Specified by:
      getMinLocalDeletionTime in interface UnfilteredSource
      Overrides:
      getMinLocalDeletionTime in class AbstractMemtable

    • partitionIterator

      public ShardedSkipListMemtable.MemtableUnfilteredPartitionIterator partitionIterator(ColumnFilter columnFilter, DataRange dataRange, SSTableReadsListener readsListener)
      Description copied from interface: UnfilteredSource
      Returns a partition iterator for the given data range.
      Parameters:
      columnFilter - filter to apply to all returned partitions
      dataRange - the partition and clustering range queried
      readsListener - a listener used to handle internal read events

    • rowIterator

      public UnfilteredRowIterator rowIterator(DecoratedKey key, Slices slices, ColumnFilter selectedColumns, boolean reversed, SSTableReadsListener listener)
      Description copied from interface: UnfilteredSource
      Returns a row iterator for the given partition, applying the specified row and column filters.
      Parameters:
      key - the partition key
      slices - the row ranges to return
      selectedColumns - filter to apply to all returned partitions
      reversed - true if the content should be returned in reverse order
      listener - a listener used to handle internal read events

    • rowIterator

      public UnfilteredRowIterator rowIterator(DecoratedKey key)

    • getFlushSet

      public Memtable.FlushablePartitionSet<AtomicBTreePartition> getFlushSet(PartitionPosition from, PartitionPosition to)
      Description copied from interface: Memtable
      Get the collection of data between the given partition boundaries in a form suitable for flushing.

    • factory

      public static org.apache.cassandra.db.memtable.ShardedSkipListMemtable.Factory factory(Map<String,String> optionsCopy)