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

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.Map<java.lang.String,java.lang.String>	getOptions()
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)
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

getOptions

public java.util.Map<java.lang.String,java.lang.String> getOptions()

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.

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:

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

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)
                                               throws java.io.IOException

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).

Throws:

java.io.IOException

getScanners

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

Throws:

java.io.IOException