org.h2.mvstore
Class MVStore.Builder

java.lang.Object
  org.h2.mvstore.MVStore.Builder

Enclosing class:

MVStore

public static class MVStore.Builder
extends java.lang.Object

A builder for an MVStore.

Constructor Summary

MVStore.Builder()

Method Summary

MVStore.Builder	cacheSize(int mb) Set the read cache size in MB.
MVStore.Builder	compressData() Compress data before writing using the LZF algorithm.
MVStore.Builder	encryptionKey(char[] password) Encrypt / decrypt the file using the given password.
MVStore.Builder	fileName(java.lang.String fileName) Use the following file name.
static MVStore.Builder	fromString(java.lang.String s) Read the configuration from a string.
MVStore	open() Open the store.
MVStore.Builder	readOnly() Open the file in read-only mode.
java.lang.String	toString()
MVStore.Builder	writeBufferSize(int mb) Set the size of the write buffer, in MB (for file-based stores).
MVStore.Builder	writeDelay(int millis) Set the maximum delay in milliseconds to store committed changes (for file-based stores).

Methods inherited from class java.lang.Object

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

Constructor Detail

MVStore.Builder

public MVStore.Builder()

Method Detail

fileName

public MVStore.Builder fileName(java.lang.String fileName)

Use the following file name. If the file does not exist, it is automatically created. The parent directory already must exist.

Parameters:

fileName - the file name

Returns:

this

encryptionKey

public MVStore.Builder encryptionKey(char[] password)

Encrypt / decrypt the file using the given password. This method has no effect for in-memory stores. The password is passed as a char array so that it can be cleared as soon as possible. Please note there is still a small risk that password stays in memory (due to Java garbage collection). Also, the hashed encryption key is kept in memory as long as the file is open.

Parameters:

password - the password

Returns:

this

readOnly

public MVStore.Builder readOnly()

Open the file in read-only mode. In this case, a shared lock will be acquired to ensure the file is not concurrently opened in write mode.

If this option is not used, the file is locked exclusively.

Please note a store may only be opened once in every JVM (no matter whether it is opened in read-only or read-write mode), because each file may be locked only once in a process.

Returns:

this

cacheSize

public MVStore.Builder cacheSize(int mb)

Set the read cache size in MB. The default is 16 MB.

Parameters:

mb - the cache size in megabytes

Returns:

this

compressData

public MVStore.Builder compressData()

Compress data before writing using the LZF algorithm. This will save about 50% of the disk space, but will slow down read and write operations slightly.

This setting only affects writes; it is not necessary to enable compression when reading, even if compression was enabled when writing.

Returns:

this

writeBufferSize

public MVStore.Builder writeBufferSize(int mb)

Set the size of the write buffer, in MB (for file-based stores). Changes are automatically stored if the buffer grows larger than this. However, unless the changes are committed later on, they are rolled back when opening the store.

The default is 4 MB.

When the value is set to 0 or lower, data is never automatically stored.

Parameters:

mb - the write buffer size, in megabytes

Returns:

this

writeDelay

public MVStore.Builder writeDelay(int millis)

Set the maximum delay in milliseconds to store committed changes (for file-based stores).

The default is 1000, meaning committed changes are stored after at most one second.

When the value is set to -1, committed changes are only written when calling the store method. When the value is set to 0, committed changes are immediately written on a commit, but please note this decreases performance and does still not guarantee the disk will actually write the data.

Parameters:

millis - the maximum delay

Returns:

this

open

public MVStore open()

Open the store.

Returns:

the opened store

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

fromString

public static MVStore.Builder fromString(java.lang.String s)

Read the configuration from a string.

Parameters:

s - the string representation

Returns:

the builder