org.h2.store

Class PageLog

java.lang.Object

org.h2.store.PageLog

public class PageLog
extends java.lang.Object

Transaction log mechanism. The stream contains a list of records. The data format for a record is:

• type (0: no-op, 1: undo, 2: commit, ...)
• data

The transaction log is split into sections. A checkpoint starts a new section.

Field Summary

Fields

Modifier and Type	Field and Description
static int	ADD Add a record to a table.
static int	CHECKPOINT Perform a checkpoint.
static int	COMMIT A commit entry of a session.
static int	FREE_LOG Free a log page.
static int	NOOP No operation.
static int	PREPARE_COMMIT A prepare commit entry for a session.
static int	REMOVE Remove a record from a table.
static int	ROLLBACK Roll back a prepared transaction.
static int	TRUNCATE Truncate a table.
static int	UNDO An undo log entry.

Method Summary

Modifier and Type	Method and Description
static Row	readRow(RowFactory rowFactory, DataReader in, Data data) Read a row from an input stream.

Methods inherited from class java.lang.Object

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

Field Detail

NOOP

public static final int NOOP

No operation.

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Constant Field Values

UNDO

public static final int UNDO

An undo log entry. Format: page id: varInt, size, page. Size 0 means uncompressed, size 1 means empty page, otherwise the size is the number of compressed bytes.

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Constant Field Values

COMMIT

public static final int COMMIT

A commit entry of a session. Format: session id: varInt.

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Constant Field Values

PREPARE_COMMIT

public static final int PREPARE_COMMIT

A prepare commit entry for a session. Format: session id: varInt, transaction name: string.

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Constant Field Values

ROLLBACK

public static final int ROLLBACK

Roll back a prepared transaction. Format: session id: varInt.

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Constant Field Values

ADD

public static final int ADD

Add a record to a table. Format: session id: varInt, table id: varInt, row.

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Constant Field Values

REMOVE

public static final int REMOVE

Remove a record from a table. Format: session id: varInt, table id: varInt, row.

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Constant Field Values

TRUNCATE

public static final int TRUNCATE

Truncate a table. Format: session id: varInt, table id: varInt.

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Constant Field Values

CHECKPOINT

public static final int CHECKPOINT

Perform a checkpoint. The log section id is incremented. Format: -

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Constant Field Values

FREE_LOG

public static final int FREE_LOG

Free a log page. Format: count: varInt, page ids: varInt

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Constant Field Values

Method Detail

readRow

public static Row readRow(RowFactory rowFactory,
                          DataReader in,
                          Data data)
                   throws java.io.IOException

Read a row from an input stream.

Parameters:

rowFactory - the row factory

in - the input stream

data - a temporary buffer

Returns:

the row

Throws:

java.io.IOException