org.apache.cassandra.db.compaction
Class AbstractCompactionStrategy

java.lang.Object
  org.apache.cassandra.db.compaction.AbstractCompactionStrategy

Direct Known Subclasses:

LeveledCompactionStrategy, SizeTieredCompactionStrategy

public abstract class AbstractCompactionStrategy
extends java.lang.Object

Pluggable compaction strategy determines how SSTables get merged. There are two main goals: - perform background compaction constantly as needed; this typically makes a tradeoff between i/o done by compaction, and merging done at read time. - perform a full (maximum possible) compaction if requested by the user

Field Summary

protected ColumnFamilyStore	cfs
protected static long	DEFAULT_TOMBSTONE_COMPACTION_INTERVAL
protected static float	DEFAULT_TOMBSTONE_THRESHOLD
java.util.Map<java.lang.String,java.lang.String>	options
protected static java.lang.String	TOMBSTONE_COMPACTION_INTERVAL_OPTION
protected static java.lang.String	TOMBSTONE_THRESHOLD_OPTION
protected long	tombstoneCompactionInterval
protected float	tombstoneThreshold

Constructor Summary

protected

AbstractCompactionStrategy(ColumnFamilyStore cfs, java.util.Map<java.lang.String,java.lang.String> options)

Method Summary

static java.util.List<SSTableReader>	filterSuspectSSTables(java.util.Collection<SSTableReader> originalCandidates) Filters SSTables that are to be blacklisted from the given collection
abstract int	getEstimatedRemainingTasks()
abstract AbstractCompactionTask	getMaximalTask(int gcBefore)
abstract long	getMaxSSTableSize()
abstract AbstractCompactionTask	getNextBackgroundTask(int gcBefore)
java.util.List<ICompactionScanner>	getScanners(java.util.Collection<SSTableReader> toCompact)
java.util.List<ICompactionScanner>	getScanners(java.util.Collection<SSTableReader> sstables, Range<Token> range) Returns a list of KeyScanners given sstables and a range on which to scan.
abstract AbstractCompactionTask	getUserDefinedTask(java.util.Collection<SSTableReader> sstables, int gcBefore)
void	shutdown() Releases any resources if this strategy is shutdown (when the CFS is reloaded after a schema change).
protected boolean	worthDroppingTombstones(SSTableReader sstable, int gcBefore) Check if given sstable is worth dropping tombstones at gcBefore.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_TOMBSTONE_THRESHOLD

protected static final float DEFAULT_TOMBSTONE_THRESHOLD

See Also:

Constant Field Values

DEFAULT_TOMBSTONE_COMPACTION_INTERVAL

protected static final long DEFAULT_TOMBSTONE_COMPACTION_INTERVAL

See Also:

Constant Field Values

TOMBSTONE_THRESHOLD_OPTION

protected static final java.lang.String TOMBSTONE_THRESHOLD_OPTION

See Also:

Constant Field Values

TOMBSTONE_COMPACTION_INTERVAL_OPTION

protected static final java.lang.String TOMBSTONE_COMPACTION_INTERVAL_OPTION

See Also:

Constant Field Values

options

public final java.util.Map<java.lang.String,java.lang.String> options

cfs

protected final ColumnFamilyStore cfs

tombstoneThreshold

protected final float tombstoneThreshold

tombstoneCompactionInterval

protected long tombstoneCompactionInterval

Constructor Detail

AbstractCompactionStrategy

protected AbstractCompactionStrategy(ColumnFamilyStore cfs,
                                     java.util.Map<java.lang.String,java.lang.String> options)

Method Detail

shutdown

public void shutdown()

Releases any resources if this strategy is shutdown (when the CFS is reloaded after a schema change). Default is to do nothing.

getNextBackgroundTask

public abstract AbstractCompactionTask getNextBackgroundTask(int gcBefore)

Parameters:

gcBefore - throw away tombstones older than this

Returns:

the next background/minor compaction task to run; null if nothing to do. Is responsible for marking its sstables as compaction-pending.

getMaximalTask

public abstract AbstractCompactionTask getMaximalTask(int gcBefore)

Parameters:

gcBefore - throw away tombstones older than this

Returns:

a compaction task that should be run to compact this columnfamilystore as much as possible. Null if nothing to do.

getUserDefinedTask

public abstract AbstractCompactionTask getUserDefinedTask(java.util.Collection<SSTableReader> sstables,
                                                          int gcBefore)

Parameters:

sstables - SSTables to compact. Must be marked as compacting.

gcBefore - throw away tombstones older than this

Returns:

a compaction task corresponding to the requested sstables. Will not be null. (Will throw if user requests an invalid compaction.)

getEstimatedRemainingTasks

public abstract int getEstimatedRemainingTasks()

Returns:

the number of background tasks estimated to still be needed for this columnfamilystore

getMaxSSTableSize

public abstract long getMaxSSTableSize()

Returns:

size in bytes of the largest sstables for this strategy

filterSuspectSSTables

public static java.util.List<SSTableReader> filterSuspectSSTables(java.util.Collection<SSTableReader> originalCandidates)

Filters SSTables that are to be blacklisted from the given collection

Parameters:

originalCandidates - The collection to check for blacklisted SSTables

Returns:

list of the SSTables with blacklisted ones filtered out

getScanners

public java.util.List<ICompactionScanner> getScanners(java.util.Collection<SSTableReader> sstables,
                                                      Range<Token> range)

Returns a list of KeyScanners given sstables and a range on which to scan. The default implementation simply grab one SSTableScanner per-sstable, but overriding this method allow for a more memory efficient solution if we know the sstable don't overlap (see LeveledCompactionStrategy for instance).

getScanners

public java.util.List<ICompactionScanner> getScanners(java.util.Collection<SSTableReader> toCompact)

worthDroppingTombstones

protected boolean worthDroppingTombstones(SSTableReader sstable,
                                          int gcBefore)

Check if given sstable is worth dropping tombstones at gcBefore. Check is skipped if tombstone_compaction_interval time does not elapse since sstable creation and returns false.

Parameters:

sstable - SSTable to check

gcBefore - time to drop tombstones

Returns:

true if given sstable's tombstones are expected to be removed