org.h2.store
Class Storage

java.lang.Object
  org.h2.store.Storage

public class Storage
extends java.lang.Object

This class represents an persistent container that stores data of a table or an index. An object contains a list of records, see Record. For each storage there is a RecordReader object that knows how to convert records into a byte array and vice versa. The data is stored in a DiskFile. A storage occupies a number of pages in a file. File format:

 int block size
 int storage id
 record data
 byte checksum
 [bytes * fillerLength]
 

Field Summary

static int

ALLOCATE_POS This value is used to indicate that the position is not yet known, and space needs to be allocated.

Constructor Summary

Storage(Database database, DiskFile file, RecordReader reader, int id)
Create a new storage object for this file.

Method Summary

void	addRecord(Session session, Record record, int pos) Add or update a record in the file.
void	flushRecord(Record rec) Write this record now.
DiskFile	getDiskFile()
int	getId() Get the unique storage id.
int	getNext(Record record) Gets the position of the next record.
Record	getRecord(Session session, int pos) Read a record from the file or cache.
int	getRecordCount() Get the number of records in this storage.
Record	getRecordIfStored(Session session, int pos) Read a record if it is stored at that location.
int	getRecordOverhead() Get the overhead to store a record (header data) in number of bytes.
RecordReader	getRecordReader() Get the record parser for this storage.
void	removeRecord(Session session, int pos) Remove a record.
void	setReader(RecordReader reader) Set the record parser for this storage.
void	setRecordCount(int recordCount) Update the record count.
void	truncate(Session session) Delete all records from this storage.
void	updateRecord(Session session, Record record) Update an existing record.

Methods inherited from class java.lang.Object

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

Field Detail

ALLOCATE_POS

public static final int ALLOCATE_POS

This value is used to indicate that the position is not yet known, and space needs to be allocated.

See Also:

Constant Field Values

Constructor Detail

Storage

public Storage(Database database,
               DiskFile file,
               RecordReader reader,
               int id)

Create a new storage object for this file.

Parameters:

database - the database

file - the file

reader - the reader that can parse records

id - the storage id

Method Detail

getRecordReader

public RecordReader getRecordReader()

Get the record parser for this storage.

Returns:

the record parser

getRecord

public Record getRecord(Session session,
                        int pos)
                 throws java.sql.SQLException

Read a record from the file or cache.

Parameters:

session - the session

pos - the position of the record

Returns:

the record

Throws:

java.sql.SQLException

getRecordIfStored

public Record getRecordIfStored(Session session,
                                int pos)
                         throws java.sql.SQLException

Read a record if it is stored at that location.

Parameters:

session - the session

pos - the position where it is stored

Returns:

the record or null

Throws:

java.sql.SQLException

getNext

public int getNext(Record record)

Gets the position of the next record.

Parameters:

record - the last record (null to get the first record)

Returns:

-1 if no record is found, otherwise the position

updateRecord

public void updateRecord(Session session,
                         Record record)
                  throws java.sql.SQLException

Update an existing record.

Parameters:

session - the session

record - the record

Throws:

java.sql.SQLException

addRecord

public void addRecord(Session session,
                      Record record,
                      int pos)
               throws java.sql.SQLException

Add or update a record in the file.

Parameters:

session - the session

record - the record

pos - the position (use ALLOCATE_POS to add a new record)

Throws:

java.sql.SQLException

removeRecord

public void removeRecord(Session session,
                         int pos)
                  throws java.sql.SQLException

Remove a record.

Parameters:

session - the session

pos - where the record is stored

Throws:

java.sql.SQLException

getId

public int getId()

Get the unique storage id.

Returns:

the id

getRecordCount

public int getRecordCount()

Get the number of records in this storage.

Returns:

the number of records

truncate

public void truncate(Session session)
              throws java.sql.SQLException

Delete all records from this storage.

Parameters:

session - the session

Throws:

java.sql.SQLException

setReader

public void setReader(RecordReader reader)

Set the record parser for this storage.

Parameters:

reader - the record parser

flushRecord

public void flushRecord(Record rec)
                 throws java.sql.SQLException

Write this record now.

Parameters:

rec - the record to write

Throws:

java.sql.SQLException

getRecordOverhead

public int getRecordOverhead()

Get the overhead to store a record (header data) in number of bytes.

Returns:

the overhead

getDiskFile

public DiskFile getDiskFile()

setRecordCount

public void setRecordCount(int recordCount)

Update the record count.

Parameters:

recordCount - the new record count