com.sleepycat.je

Class DiskOrderedCursorConfig

java.lang.Object

com.sleepycat.je.DiskOrderedCursorConfig

All Implemented Interfaces:

java.lang.Cloneable

public class DiskOrderedCursorConfig
extends java.lang.Object
implements java.lang.Cloneable

Specifies the attributes of a DiskOrderedCursor.

Since:

5.0

Field Summary

Fields

Modifier and Type	Field and Description
static DiskOrderedCursorConfig	DEFAULT Default configuration used if null is passed to methods that create a cursor.

Constructor Summary

Constructors

Constructor and Description
DiskOrderedCursorConfig() An instance created using the default constructor is initialized with the system's default settings.

Method Summary

Modifier and Type	Method and Description
DiskOrderedCursorConfig	clone() Returns a copy of this configuration object.
boolean	getBINsOnly() Returns true if the DiskOrderedCursor is configured to scan BINs only, returning all record keys and only those record data that are embedded in the BINs.
long	getInternalMemoryLimit() Returns the maximum amount of JE Cache Memory that the DiskOrderedScan can use at one time.
boolean	getKeysOnly() Returns true if the DiskOrderedCursor is configured to return only keys.
long	getLSNBatchSize() Returns the maximum number of LSNs to be sorted that this DiskOrderedCursor is configured for.
long	getMaxSeedMillisecs() Deprecated. this method returns zero and will be removed in a future release.
long	getMaxSeedNodes() Deprecated. this method returns zero and will be removed in a future release.
int	getQueueSize() Returns the maximum number of entries in the queue before the DiskOrderedCursor producer thread blocks.
DiskOrderedCursorConfig	setBINsOnly(boolean binsOnly) Specify whether the DiskOrderedCursor should scan the BINs only.
DiskOrderedCursorConfig	setInternalMemoryLimit(long internalMemoryLimit) Set the maximum amount of JE Cache Memory that the DiskOrderedScan can use at one time.
DiskOrderedCursorConfig	setKeysOnly(boolean keysOnly) Specify whether the DiskOrderedCursor should return only the key or key + data.
DiskOrderedCursorConfig	setLSNBatchSize(long lsnBatchSize) Set the maximum number of LSNs to gather and sort at any one time.
DiskOrderedCursorConfig	setMaxSeedMillisecs(long maxSeedMillisecs) Deprecated. this method has no effect and will be removed in a future release.
DiskOrderedCursorConfig	setMaxSeedNodes(long maxSeedNodes) Deprecated. this method has no effect and will be removed in a future release.
DiskOrderedCursorConfig	setQueueSize(int queueSize) Set the queue size for entries being passed between the DiskOrderedCursor producer thread and the application's consumer thread.
java.lang.String	toString() Returns the values for each configuration attribute.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT

public static final DiskOrderedCursorConfig DEFAULT

Default configuration used if null is passed to methods that create a cursor.

Constructor Detail

DiskOrderedCursorConfig

public DiskOrderedCursorConfig()

An instance created using the default constructor is initialized with the system's default settings.

Method Detail

setKeysOnly

public DiskOrderedCursorConfig setKeysOnly(boolean keysOnly)

Specify whether the DiskOrderedCursor should return only the key or key + data. The default value is false (key + data). If keyOnly is true, the performance of the disk ordered scan will be better, because the Cursor only descends to the BIN level.

Parameters:

keysOnly - If true, return only keys from this cursor.

Returns:

this

getKeysOnly

public boolean getKeysOnly()

Returns true if the DiskOrderedCursor is configured to return only keys. Returns false if it is configured to return keys + data.

Returns:

true if the DiskOrderedCursor is configured to return keys only.

setBINsOnly

public DiskOrderedCursorConfig setBINsOnly(boolean binsOnly)

Specify whether the DiskOrderedCursor should scan the BINs only. If true, the performance of the disk ordered scan will be better, because LNs are not read from disk. However, in this case, the data portion of a record will be returned only if it is embedded in the BIN; otherwise only the key will be returned.

Parameters:

binsOnly - If true, return keys and, if available, the associated embedded data.

Returns:

this

getBINsOnly

public boolean getBINsOnly()

Returns true if the DiskOrderedCursor is configured to scan BINs only, returning all record keys and only those record data that are embedded in the BINs.

Returns:

true if the DiskOrderedCursor is configured to scan BINs only.

setLSNBatchSize

public DiskOrderedCursorConfig setLSNBatchSize(long lsnBatchSize)

Set the maximum number of LSNs to gather and sort at any one time. The default is an unlimited number of LSNs. Setting this lower causes the DiskOrderedScan to use less memory, but it sorts and processes LSNs more frequently thereby causing slower performance. Setting this higher will in general improve performance at the expense of memory. Each LSN uses 16 bytes of memory.

Parameters:

lsnBatchSize - the maximum number of LSNs to accumulate and sort per batch.

Returns:

this

getLSNBatchSize

public long getLSNBatchSize()

Returns the maximum number of LSNs to be sorted that this DiskOrderedCursor is configured for.

Returns:

the maximum number of LSNs to be sorted that this DiskOrderedCursor is configured for.

setInternalMemoryLimit

public DiskOrderedCursorConfig setInternalMemoryLimit(long internalMemoryLimit)

Set the maximum amount of JE Cache Memory that the DiskOrderedScan can use at one time. The default is an unlimited amount of memory. Setting this lower causes the DiskOrderedScan to use less memory, but it sorts and processes LSNs more frequently thereby generally causing slower performance. Setting this higher will in general improve performance at the expense of JE cache memory.

Parameters:

internalMemoryLimit - the maximum number of non JE Cache bytes to use.

Returns:

this

See Also:

Cache Statistics: Unexpected Sizes

getInternalMemoryLimit

public long getInternalMemoryLimit()

Returns the maximum amount of JE Cache Memory that the DiskOrderedScan can use at one time.

Returns:

the maximum amount of non JE Cache Memory that preload can use at one time.

setQueueSize

public DiskOrderedCursorConfig setQueueSize(int queueSize)

Set the queue size for entries being passed between the DiskOrderedCursor producer thread and the application's consumer thread. If the queue size reaches this number of entries, the producer thread will block until the application thread removes one or more entries (by calling ForwardCursor.getNext(). The default is 1000.

Parameters:

queueSize - the maximum number of entries the queue can hold before the producer thread blocks.

Returns:

this

getQueueSize

public int getQueueSize()

Returns the maximum number of entries in the queue before the DiskOrderedCursor producer thread blocks.

Returns:

the maximum number of entries in the queue before the DiskOrderedCursor producer thread blocks.

setMaxSeedMillisecs

public DiskOrderedCursorConfig setMaxSeedMillisecs(long maxSeedMillisecs)

Deprecated. this method has no effect and will be removed in a future release.

getMaxSeedMillisecs

public long getMaxSeedMillisecs()

Deprecated. this method returns zero and will be removed in a future release.

setMaxSeedNodes

public DiskOrderedCursorConfig setMaxSeedNodes(long maxSeedNodes)

Deprecated. this method has no effect and will be removed in a future release.

getMaxSeedNodes

public long getMaxSeedNodes()

Deprecated. this method returns zero and will be removed in a future release.

clone

public DiskOrderedCursorConfig clone()

Returns a copy of this configuration object.

Overrides:

clone in class java.lang.Object

toString

public java.lang.String toString()

Returns the values for each configuration attribute.

Overrides:

toString in class java.lang.Object

Returns:

the values for each configuration attribute.