iitb.con.indexing.isam
Class ISAMTree<K extends java.lang.Comparable<K>>

java.lang.Object
  iitb.con.indexing.isam.ISAMTree<K>

All Implemented Interfaces:

IndexTree<K>

public class ISAMTree<K extends java.lang.Comparable<K>>
extends java.lang.Object
implements IndexTree<K>

ISAMTree is index structure to index the instances based on their attribute.

ISAM stands for Indexed Sequential Access Method, a method for indexing data for fast retrieval. In an ISAM system, data is organized into records which are composed of fixed length fields. Records are stored sequentially (as leaf nodes), originally to speed access on a disk. A secondary set of hash tables (non-leaf nodes) contain "pointers" into the leaf-node blocks, allowing individual records to be retrieved without having to search the entire data set.

ISAM is a static indexing structure, works well for the structure involving few updates. That is the reason there is no update method provided. Hence user need to create index again if the data gets changed.

Field Summary

Fields inherited from interface iitb.con.indexing.IndexTree

LEAF_EXT, NON_LEAF_EXT

Constructor Summary

ISAMTree(java.lang.String fileName, java.lang.String mode)
Constructs the ISAMTree for the specified index file

Method Summary

void	close() Closes the index structure files.
void	create(java.util.List<Node<K>> nodes) Creates the index file for the give nodes list
KeyList<K,java.lang.Short>	getMetaIndex(K key) Returns the meta-index of the index structure.
int[]	getValues(K key) Retrieves the values for the specified key

Methods inherited from class java.lang.Object

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

Constructor Detail

ISAMTree

public ISAMTree(java.lang.String fileName,
                java.lang.String mode)
         throws java.io.FileNotFoundException,
                java.io.IOException

Constructs the ISAMTree for the specified index file

Parameters:

fileName - index file name

mode - file opening mode (r, rw)

Throws:

java.io.FileNotFoundException - if file not found

java.io.IOException - if file operation fails

Method Detail

close

public void close()
           throws java.io.IOException

Closes the index structure files.

Specified by:

close in interface IndexTree<K extends java.lang.Comparable<K>>

Throws:

java.io.IOException - if the file operation fails

create

public void create(java.util.List<Node<K>> nodes)
            throws java.io.IOException

Creates the index file for the give nodes list

Specified by:

create in interface IndexTree<K extends java.lang.Comparable<K>>

Parameters:

nodes - nodes list - Node

Throws:

java.io.IOException - if file operation fails

getMetaIndex

public KeyList<K,java.lang.Short> getMetaIndex(K key)
                                                                        throws java.io.IOException

Returns the meta-index of the index structure. The meta-index is a basically the non-leaf node of the index tree structure.

Specified by:

getMetaIndex in interface IndexTree<K extends java.lang.Comparable<K>>

Parameters:

key - key of the index structure

Returns:

key-id list ; KeyList

Throws:

java.io.IOException - if the file operation fails

getValues

public int[] getValues(K key)
                throws java.io.IOException

Retrieves the values for the specified key

Specified by:

getValues in interface IndexTree<K extends java.lang.Comparable<K>>

Parameters:

key - key of the index structure

Returns:

matched values for the given key

Throws:

java.io.IOException - if the file operation fails