org.basex.data
Class DiskData

java.lang.Object
  org.basex.data.Data
      org.basex.data.DiskData

public final class DiskData
extends Data

This class stores and organizes the node table and the index structures for textual content. All nodes in the table are accessed by their implicit pre value. Some restrictions on the data are currently given:

• The table is limited to 2^31 entries (pre values are signed int's)
• A maximum of 2^16 different tag and attribute names is allowed
• A tag can have a maximum of 256 attributes

Each node occupies 128 bits. The current storage layout looks like follows:

  ELEMENTS:
 - Byte     0: Node kind (TAG)
 - Byte   1-2: Tag Reference
 - Byte     3: Number of attributes
 - Byte  4- 7: Number of descendants (size)
 - Byte  8-11: Relative parent reference
 - Byte 12-15: Unique Node ID
 TEXT NODES:
 - Byte     0: Node kind (TEXT/PI/COMM)
 - Byte  3- 7: Text reference
 - Byte  8-11: Relative parent reference
 - Byte 12-15: Unique Node ID
 ATTRIBUTE NODES:
 - Byte     0: Node kind (ATTR)
 - Byte   1-2: Attribute name reference
 - Byte  3- 7: Attribute value reference
 - Byte    11: Relative parent reference
 - Byte 12-15: Unique Node ID
 

Author:

Workgroup DBIS, University of Konstanz 2005-07, ISC License, Christian Gruen, Tim Petrowsky

Field Summary

Fields inherited from class org.basex.data.Data

ATTR, atts, COMM, contentID, deepfs, dirID, DOC, ELEM, fileID, meta, nameID, PI, size, sizeID, suffixID, tags, TEXT, timeID

Constructor Summary

DiskData(java.lang.String db)
Default Constructor.

DiskData(java.lang.String db, boolean index)
Constructor, specifying if indexes are to be opened as well.

Method Summary

int	attNameID(int pre) Returns an attribute name id (reference to the attribute name index).
double	attNum(int pre) Returns an attribute value as double value.
int	attSize(int pre, int kind) Returns a number of attributes.
byte[]	attValue(int pre) Returns an attribute value.
void	close() Closes the current database.
void	closeIndex(Index.TYPE index) Closes the specified index.
void	cls() Closes the database without writing data back to disk.
void	delete(int pre) Deletes a node and its descendants.
void	flush() Flushes the table data.
int[][]	ftIDs(byte[] word, FTOption ftO) Returns the indexed id references for the specified fulltext token.
int	id(int pre) Returns a unique node id.
void	info(PrintOutput out) Returns info on the index structures.
void	insert(int pre, int par, byte[] val, byte kind) Inserts a tag name, text node, comment or processing instruction.
void	insert(int pre, int par, byte[] name, byte[] val) Inserts an attribute.
void	insert(int pre, int par, Data td) Insert a data instance at the specified pre value.
int	kind(int pre) Returns a node kind.
int	nrFTIDs(byte[] token) Returns the number of indexed id references for the specified token.
void	openIndex(Index.TYPE type, Index index) Opens the specified index.
int	parent(int pre, int kind) Returns a pre value of the parent node.
int	pre(int id) Returns a pre value.
int	size(int pre, int kind) Returns a size value (number of descendant table entries).
int	tagID(int pre) Returns a tag id (reference to the tag index).
byte[]	text(int pre) Returns a text.
int	textLen(int pre) Returns a text length.
double	textNum(int pre) Returns a text as double value.
void	update(int pre, byte[] value) Updates a tag name, text node, comment or processing instruction.
void	update(int pre, byte[] name, byte[] val) Updates an attribute name and value.

Methods inherited from class org.basex.data.Data

atom, atomNum, attName, attNameID, attValue, ids, initNames, noLeaf, nrIDs, nrTags, tag, tagID

Methods inherited from class java.lang.Object

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

Constructor Detail

DiskData

public DiskData(java.lang.String db)
         throws java.io.IOException

Default Constructor.

Parameters:

db - name of database

Throws:

java.io.IOException - IO Exception

DiskData

public DiskData(java.lang.String db,
                boolean index)
         throws java.io.IOException

Constructor, specifying if indexes are to be opened as well.

Parameters:

db - name of database

index - open indexes

Throws:

java.io.IOException - IO Exception

Method Detail

attNameID

public int attNameID(int pre)

Description copied from class: Data

Returns an attribute name id (reference to the attribute name index).

Specified by:

attNameID in class Data

Parameters:

pre - pre value

Returns:

token reference

attNum

public double attNum(int pre)

Description copied from class: Data

Returns an attribute value as double value.

Specified by:

attNum in class Data

Parameters:

pre - pre value

Returns:

numeric value

attSize

public int attSize(int pre,
                   int kind)

Description copied from class: Data

Returns a number of attributes.

Specified by:

attSize in class Data

Parameters:

pre - pre value

kind - node kind

Returns:

number of attributes

attValue

public byte[] attValue(int pre)

Description copied from class: Data

Returns an attribute value.

Specified by:

attValue in class Data

Parameters:

pre - pre value

Returns:

atomized value

close

public void close()
           throws java.io.IOException

Description copied from class: Data

Closes the current database.

Specified by:

close in class Data

Throws:

java.io.IOException - in case the database could not be closed

closeIndex

public void closeIndex(Index.TYPE index)
                throws java.io.IOException

Description copied from class: Data

Closes the specified index.

Specified by:

closeIndex in class Data

Parameters:

index - index to be closed

Throws:

java.io.IOException - in case the index could not be closed

cls

public void cls()
         throws java.io.IOException

Closes the database without writing data back to disk.

Throws:

java.io.IOException - I/O exception

delete

public void delete(int pre)

Description copied from class: Data

Deletes a node and its descendants.

Specified by:

delete in class Data

Parameters:

pre - pre value of the node to delete

flush

public void flush()

Description copied from class: Data

Flushes the table data.

Specified by:

flush in class Data

ftIDs

public int[][] ftIDs(byte[] word,
                     FTOption ftO)

Description copied from class: Data

Returns the indexed id references for the specified fulltext token.

Specified by:

ftIDs in class Data

Parameters:

word - token to be looked up

ftO - fulltext options

Returns:

id array

id

public int id(int pre)

Description copied from class: Data

Returns a unique node id.

Specified by:

id in class Data

Parameters:

pre - pre value

Returns:

node id

info

public void info(PrintOutput out)
          throws java.io.IOException

Description copied from class: Data

Returns info on the index structures.

Specified by:

info in class Data

Parameters:

out - output stream

Throws:

java.io.IOException - I/O exception

insert

public void insert(int pre,
                   int par,
                   byte[] val,
                   byte kind)

Description copied from class: Data

Inserts a tag name, text node, comment or processing instruction.

Specified by:

insert in class Data

Parameters:

pre - pre value

par - parent of node

val - value to be inserted

kind - node kind

insert

public void insert(int pre,
                   int par,
                   byte[] name,
                   byte[] val)

Description copied from class: Data

Inserts an attribute.

Specified by:

insert in class Data

Parameters:

pre - pre value

par - parent of node

name - attribute name

val - attribute value

insert

public void insert(int pre,
                   int par,
                   Data td)

Description copied from class: Data

Insert a data instance at the specified pre value. Note that the specified data instance must differ from this instance.

Specified by:

insert in class Data

Parameters:

pre - pre value

par - parent of node

td - data instance to copy from

kind

public int kind(int pre)

Description copied from class: Data

Returns a node kind.

Specified by:

kind in class Data

Parameters:

pre - pre value

Returns:

node kind

nrFTIDs

public int nrFTIDs(byte[] token)

Description copied from class: Data

Returns the number of indexed id references for the specified token.

Specified by:

nrFTIDs in class Data

Parameters:

token - token to be looked up

Returns:

id array

openIndex

public void openIndex(Index.TYPE type,
                      Index index)

Description copied from class: Data

Opens the specified index.

Specified by:

openIndex in class Data

Parameters:

type - index to be opened

index - index instance

parent

public int parent(int pre,
                  int kind)

Description copied from class: Data

Returns a pre value of the parent node.

Specified by:

parent in class Data

Parameters:

pre - pre value

kind - node kind

Returns:

pre value of the parent node

pre

public int pre(int id)

Description copied from class: Data

Returns a pre value.

Specified by:

pre in class Data

Parameters:

id - unique node id

Returns:

pre value or -1 if id was not found

size

public int size(int pre,
                int kind)

Description copied from class: Data

Returns a size value (number of descendant table entries).

Specified by:

size in class Data

Parameters:

pre - pre value

kind - node kind

Returns:

size value

tagID

public int tagID(int pre)

Description copied from class: Data

Returns a tag id (reference to the tag index).

Specified by:

tagID in class Data

Parameters:

pre - pre value

Returns:

token reference

text

public byte[] text(int pre)

Description copied from class: Data

Returns a text.

Specified by:

text in class Data

Parameters:

pre - pre value

Returns:

atomized value

textLen

public int textLen(int pre)

Description copied from class: Data

Returns a text length.

Specified by:

textLen in class Data

Parameters:

pre - pre value

Returns:

atomized value

textNum

public double textNum(int pre)

Description copied from class: Data

Returns a text as double value.

Specified by:

textNum in class Data

Parameters:

pre - pre value

Returns:

numeric value

update

public void update(int pre,
                   byte[] value)

Description copied from class: Data

Updates a tag name, text node, comment or processing instruction.

Specified by:

update in class Data

Parameters:

pre - pre of the text node to change

value - value to be updated

update

public void update(int pre,
                   byte[] name,
                   byte[] val)

Description copied from class: Data

Updates an attribute name and value.

Specified by:

update in class Data

Parameters:

pre - pre of node to insert after

name - attribute name

val - attribute value