org.rocksdb

Class WriteOptions

java.lang.Object

org.rocksdb.RocksObject

org.rocksdb.WriteOptions

public class WriteOptions
extends RocksObject

Options that control write operations. Note that developers should call WriteOptions.dispose() to release the c++ side memory before a WriteOptions instance runs out of scope.

Field Summary

Fields inherited from class org.rocksdb.RocksObject

nativeHandle_

Constructor Summary

Constructors

Constructor and Description
WriteOptions() Construct WriteOptions instance.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	disableWAL() If true, writes will not first go to the write ahead log, and the write may got lost after a crash.
protected void	disposeInternal() The helper function of dispose() which all subclasses of RocksObject must implement to release their associated C++ resource.
WriteOptions	setDisableWAL(boolean flag) If true, writes will not first go to the write ahead log, and the write may got lost after a crash.
WriteOptions	setSync(boolean flag) If true, the write will be flushed from the operating system buffer cache (by calling WritableFile::Sync()) before the write is considered complete.
boolean	sync() If true, the write will be flushed from the operating system buffer cache (by calling WritableFile::Sync()) before the write is considered complete.

Methods inherited from class org.rocksdb.RocksObject

disOwnNativeHandle, dispose, finalize, isInitialized, isOwningNativeHandle

Methods inherited from class java.lang.Object

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

Constructor Detail

WriteOptions

public WriteOptions()

Construct WriteOptions instance.

Method Detail

disposeInternal

protected void disposeInternal()

Description copied from class: RocksObject

The helper function of dispose() which all subclasses of RocksObject must implement to release their associated C++ resource.

Specified by:

disposeInternal in class RocksObject

setSync

public WriteOptions setSync(boolean flag)

If true, the write will be flushed from the operating system buffer cache (by calling WritableFile::Sync()) before the write is considered complete. If this flag is true, writes will be slower. If this flag is false, and the machine crashes, some recent writes may be lost. Note that if it is just the process that crashes (i.e., the machine does not reboot), no writes will be lost even if sync==false. In other words, a DB write with sync==false has similar crash semantics as the "write()" system call. A DB write with sync==true has similar crash semantics to a "write()" system call followed by "fdatasync()". Default: false

Parameters:

flag - a boolean flag to indicate whether a write should be synchronized.

Returns:

the instance of the current WriteOptions.

sync

public boolean sync()

If true, the write will be flushed from the operating system buffer cache (by calling WritableFile::Sync()) before the write is considered complete. If this flag is true, writes will be slower. If this flag is false, and the machine crashes, some recent writes may be lost. Note that if it is just the process that crashes (i.e., the machine does not reboot), no writes will be lost even if sync==false. In other words, a DB write with sync==false has similar crash semantics as the "write()" system call. A DB write with sync==true has similar crash semantics to a "write()" system call followed by "fdatasync()".

Returns:

boolean value indicating if sync is active.

setDisableWAL

public WriteOptions setDisableWAL(boolean flag)

If true, writes will not first go to the write ahead log, and the write may got lost after a crash.

Parameters:

flag - a boolean flag to specify whether to disable write-ahead-log on writes.

Returns:

the instance of the current WriteOptions.

disableWAL

public boolean disableWAL()

If true, writes will not first go to the write ahead log, and the write may got lost after a crash.

Returns:

boolean value indicating if WAL is disabled.