org.h2.value
Class ValueLob

java.lang.Object
  org.h2.value.Value
      org.h2.value.ValueLob

public class ValueLob
extends Value

Implementation of the BLOB and CLOB data types. Small objects are kept in memory and stored in the record. Large objects are stored in their own files. When large objects are set in a prepared statement, they are first stored as 'temporary' files. Later, when they are used in a record, and when the record is stored, the lob files are linked: the file is renamed using the file format (tableId).(objectId). There is one exception: large variables are stored in the file (-1).(objectId). When lobs are deleted, they are first renamed to a temp file, and if the delete operation is committed the file is deleted. Data compression is supported.

Nested Class Summary

Nested classes/interfaces inherited from class org.h2.value.Value

Value.ValueBlob, Value.ValueClob

Field Summary

Fields inherited from class org.h2.value.Value

ARRAY, BLOB, BOOLEAN, BYTE, BYTES, CLOB, DATE, DECIMAL, DOUBLE, FLOAT, INT, JAVA_OBJECT, LONG, NULL, RESULT_SET, SHORT, STRING, STRING_FIXED, STRING_IGNORECASE, TIME, TIMESTAMP, TYPE_COUNT, UNKNOWN, UUID

Method Summary

void	close() Close the underlying resource, if any.
protected int	compareSecure(Value v, CompareMode mode) Compare the value with another value of the same type.
Value	convertTo(int t) Convert a lob to another data type.
void	convertToFileIfRequired(DataHandler h) Store the lob data to a file if the size of the buffer it larger than the maximum size for an in-place lob.
ValueLob	copyToTemp() Create an independent copy of this temporary value.
static ValueLob	createBlob(java.io.InputStream in, long length, DataHandler handler) Create a BLOB value from a stream.
static ValueLob	createClob(java.io.Reader in, long length, DataHandler handler) Create a CLOB value from a stream.
static ValueLob	createSmallLob(int type, byte[] small) Create a small lob using the given byte array.
boolean	equals(java.lang.Object other) Check if the two values have the same hash code.
byte[]	getBytes()
byte[]	getBytesNoCopy()
int	getDisplaySize() Get the display size in characters.
java.lang.String	getFileName() Get the current file name where the lob is saved.
java.io.InputStream	getInputStream()
int	getMemory() Get the memory used by this object.
java.lang.Object	getObject() Get the value as an object.
int	getObjectId() Get the current object id of this lob.
long	getPrecision() Get the precision.
java.io.Reader	getReader()
byte[]	getSmall() Get the data if this a small lob value.
java.lang.String	getSQL() Get the SQL expression for this value.
java.lang.String	getString() Get the value as a string.
int	getTableId() Get the current table id of this lob.
java.lang.String	getTraceSQL() Get a medium size SQL expression for debugging or tracing.
int	getType() Get the value type.
int	hashCode()
boolean	isFileBased() Check if this value is stored in it's own file.
boolean	isLinked() Check if this value is linked to a specific table.
Value	link(DataHandler h, int tabId) Link a large value to a given table.
static ValueLob	open(int type, DataHandler handler, int tableId, int objectId, long precision, boolean compression) Create a LOB value with the given parameters.
static void	removeAllForTable(DataHandler handler, int tableId) Remove all lobs for a given table id.
static void	resetDirCounter() Reset the directory counter as if the process was stopped.
void	set(java.sql.PreparedStatement prep, int parameterIndex) Set the value as a parameter in a prepared statement.
void	setFileName(java.lang.String fileName, boolean linked) Set the file name of this lob value.
void	unlink() Mark any underlying resource as 'not linked to any table'.
boolean	useCompression() Check if this lob value is compressed.

Methods inherited from class org.h2.value.Value

add, checkPrecision, clearCache, compareTo, compareTypeSave, convertPrecision, convertScale, divide, getBigDecimal, getBoolean, getByte, getDate, getDateNoCopy, getDouble, getFloat, getHigherOrder, getInt, getLong, getScale, getShort, getSignum, getTime, getTimeNoCopy, getTimestamp, getTimestampNoCopy, multiply, negate, subtract, throwUnsupportedExceptionForType, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

createSmallLob

public static ValueLob createSmallLob(int type,
                                      byte[] small)

Create a small lob using the given byte array.

Parameters:

type - the type (Value.BLOB or CLOB)

small - the byte array

Returns:

the lob value

open

public static ValueLob open(int type,
                            DataHandler handler,
                            int tableId,
                            int objectId,
                            long precision,
                            boolean compression)

Create a LOB value with the given parameters.

Parameters:

type - the data type

handler - the file handler

tableId - the table object id

objectId - the object id

precision - the precision (length in elements)

compression - if compression is used

Returns:

the value object

createClob

public static ValueLob createClob(java.io.Reader in,
                                  long length,
                                  DataHandler handler)

Create a CLOB value from a stream.

Parameters:

in - the reader

length - the number of characters to read, or -1 for no limit

handler - the data handler

Returns:

the lob value

resetDirCounter

public static void resetDirCounter()

Reset the directory counter as if the process was stopped. This method is for debugging only (to simulate stopping a process).

createBlob

public static ValueLob createBlob(java.io.InputStream in,
                                  long length,
                                  DataHandler handler)

Create a BLOB value from a stream.

Parameters:

in - the input stream

length - the number of characters to read, or -1 for no limit

handler - the data handler

Returns:

the lob value

convertTo

public Value convertTo(int t)

Convert a lob to another data type. The data is fully read in memory except when converting to BLOB or CLOB.

Overrides:

convertTo in class Value

Parameters:

t - the new type

Returns:

the converted value

isLinked

public boolean isLinked()

Description copied from class: Value

Check if this value is linked to a specific table. For values that are kept fully in memory, this method returns false.

Overrides:

isLinked in class Value

Returns:

true if it is

getFileName

public java.lang.String getFileName()

Get the current file name where the lob is saved.

Returns:

the file name or null

close

public void close()

Description copied from class: Value

Close the underlying resource, if any. For values that are kept fully in memory this method has no effect.

Overrides:

close in class Value

unlink

public void unlink()

Description copied from class: Value

Mark any underlying resource as 'not linked to any table'. For values that are kept fully in memory this method has no effect.

Overrides:

unlink in class Value

link

public Value link(DataHandler h,
                  int tabId)

Description copied from class: Value

Link a large value to a given table. For values that are kept fully in memory this method has no effect.

Overrides:

link in class Value

Parameters:

h - the data handler

tabId - the table to link to

Returns:

the new value or itself

getTableId

public int getTableId()

Get the current table id of this lob.

Overrides:

getTableId in class Value

Returns:

the table id

getObjectId

public int getObjectId()

Get the current object id of this lob.

Returns:

the object id

getType

public int getType()

Description copied from class: Value

Get the value type.

Specified by:

getType in class Value

Returns:

the type

getPrecision

public long getPrecision()

Description copied from class: Value

Get the precision.

Specified by:

getPrecision in class Value

Returns:

the precision

getString

public java.lang.String getString()

Description copied from class: Value

Get the value as a string.

Specified by:

getString in class Value

Returns:

the string

getBytes

public byte[] getBytes()

Overrides:

getBytes in class Value

getBytesNoCopy

public byte[] getBytesNoCopy()

Overrides:

getBytesNoCopy in class Value

hashCode

public int hashCode()

Specified by:

hashCode in class Value

compareSecure

protected int compareSecure(Value v,
                            CompareMode mode)

Description copied from class: Value

Compare the value with another value of the same type.

Specified by:

compareSecure in class Value

Parameters:

v - the other value

mode - the compare mode

Returns:

0 if both values are equal, -1 if the other value is smaller, and 1 otherwise

getObject

public java.lang.Object getObject()

Description copied from class: Value

Get the value as an object.

Specified by:

getObject in class Value

Returns:

the object

getReader

public java.io.Reader getReader()

Overrides:

getReader in class Value

getInputStream

public java.io.InputStream getInputStream()

Overrides:

getInputStream in class Value

set

public void set(java.sql.PreparedStatement prep,
                int parameterIndex)
         throws java.sql.SQLException

Description copied from class: Value

Set the value as a parameter in a prepared statement.

Specified by:

set in class Value

Parameters:

prep - the prepared statement

parameterIndex - the parameter index

Throws:

java.sql.SQLException

getSQL

public java.lang.String getSQL()

Description copied from class: Value

Get the SQL expression for this value.

Specified by:

getSQL in class Value

Returns:

the SQL expression

getTraceSQL

public java.lang.String getTraceSQL()

Description copied from class: Value

Get a medium size SQL expression for debugging or tracing. If the precision is too large, only a subset of the value is returned.

Overrides:

getTraceSQL in class Value

Returns:

the SQL expression

getSmall

public byte[] getSmall()

Get the data if this a small lob value.

Overrides:

getSmall in class Value

Returns:

the data

getDisplaySize

public int getDisplaySize()

Description copied from class: Value

Get the display size in characters.

Specified by:

getDisplaySize in class Value

Returns:

the display size

equals

public boolean equals(java.lang.Object other)

Description copied from class: Value

Check if the two values have the same hash code. No data conversion is made; this method returns false if the other object is not of the same class. For some values, compareTo may return 0 even if equals return false. Example: ValueDecimal 0.0 and 0.00.

Specified by:

equals in class Value

Parameters:

other - the other value

Returns:

true if they are equal

convertToFileIfRequired

public void convertToFileIfRequired(DataHandler h)

Store the lob data to a file if the size of the buffer it larger than the maximum size for an in-place lob.

Parameters:

h - the data handler

removeAllForTable

public static void removeAllForTable(DataHandler handler,
                                     int tableId)

Remove all lobs for a given table id.

Parameters:

handler - the data handler

tableId - the table id

useCompression

public boolean useCompression()

Check if this lob value is compressed.

Returns:

true if it is

isFileBased

public boolean isFileBased()

Description copied from class: Value

Check if this value is stored in it's own file. For values that are kept fully in memory, this method returns false.

Overrides:

isFileBased in class Value

Returns:

true if it is

setFileName

public void setFileName(java.lang.String fileName,
                        boolean linked)

Set the file name of this lob value.

Parameters:

fileName - the file name

linked - if the lob is linked

getMemory

public int getMemory()

Description copied from class: Value

Get the memory used by this object.

Overrides:

getMemory in class Value

Returns:

the memory used in bytes

copyToTemp

public ValueLob copyToTemp()

Create an independent copy of this temporary value. The file will not be deleted automatically.

Overrides:

copyToTemp in class Value

Returns:

the value