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

Constructor Summary

protected

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

Method Summary

abstract java.util.List<AbstractCompactionTask>	getBackgroundTasks(int gcBefore)
abstract int	getEstimatedRemainingTasks()
abstract java.util.List<AbstractCompactionTask>	getMaximalTasks(int gcBefore)
abstract long	getMaxSSTableSize()
abstract AbstractCompactionTask	getUserDefinedTask(java.util.Collection<SSTableReader> sstables, int gcBefore)
abstract boolean	isKeyExistenceExpensive(java.util.Set<? extends SSTable> sstablesToIgnore)
void	shutdown() Releases any resources if this strategy is shutdown (when the CFS is reloaded after a schema change).

Methods inherited from class java.lang.Object

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

Field Detail

cfs

protected final ColumnFamilyStore cfs

options

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

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.

getBackgroundTasks

public abstract java.util.List<AbstractCompactionTask> getBackgroundTasks(int gcBefore)

Parameters:

gcBefore - throw away tombstones older than this

Returns:

a list of compaction tasks that should run in the background to get the sstable count down to desired parameters. Will not be null, but may be empty.

getMaximalTasks

public abstract java.util.List<AbstractCompactionTask> getMaximalTasks(int gcBefore)

Parameters:

gcBefore - throw away tombstones older than this

Returns:

a list of compaction tasks that should be run to compact this columnfamilystore as much as possible. Will not be null, but may be empty.

getUserDefinedTask

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

Parameters:

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

isKeyExistenceExpensive

public abstract boolean isKeyExistenceExpensive(java.util.Set<? extends SSTable> sstablesToIgnore)

Returns:

true if checking for whether a key exists, ignoring @param sstablesToIgnore, is going to be expensive