Holistic Twig Joins:Optimal XML Pattern Matching

Written by:Nicolas BrunoNick Koudas

Divesh Srivastava

Presented by:Jose Luna

John Bassett

What is XML?

• Extensible Markup Language

• Tag-based markup language that allows you to share structured information

• Information is easily transferred across systems

XML Example

Twigs

• A twig is simply a subtree• Example (ignore numbers for now):

What is XQuery?

• Query language designed to query collections of XML data

• XQuery is a full-fledged query language, but we are only concerned with ancestor-descendent and parent-child relationships.

XQuery Relationships

• Single line indicates parent-child relationship

• Double line indicates an ancestor-descendent relationship

XQuery Example 1

• Query:book[title = ‘XML’ and year = ‘2000’]

• Associated query tree:

XQuery Example 2

• Query:book[title = ‘XML’]//author[fn =

‘jane’ AND ln = ‘doe’]

• Associatedquery tree:

XB-Trees

• An XB-Tree is simply a B-Tree that is designed to index this XML data using the positional data

• Indexing using (LeftPos : RightPos)

• Querying is done just as is done in a regular B-Tree

XB-Tree Example

Experimental Results

Experimental Results

Experimental Results

Experimental Results

Experimental Results

Experimental Results

Questions?

Thank you!