XMLtoRelational Data Mapping Algorithms OXInsert and SDM

1
XML-to-Relational Data Mapping Algorithms
OXInsert and SDM

• Speaker Artem Chebotko
• Email artem_at_wayne.edu
• Wayne State University
• Joint work with Mustafa Atay, Shiyong Lu and
  Farshad Fotouhi

2
Introduction

• XML has emerged as the standard for representing
  and exchanging data on the World Wide Web.
• The increasing amount of XML documents requires
  the need to store and query XML documents
  efficiently.

3
Current approaches of storing and querying XML
documents

• Native XML repositories, e.g., Software AGs
  Tamino, eXcelons XIS.
• XML-enabled commercial database systems such as
  SQL Server, Oracle, and DB2
• Using RDBMS/ODBMS to store and query XML
  documents.

4
Issues of the relational approach

• Schema Mapping
• XML data model needs to be mapped into the
  relational model
• Data Mapping
• XML documents need to be shredded and composed
  into tuples to be inserted into the relational
  database
• Query Mapping
• XML queries need to be translated into SQL
  queries
• Reverse Data Mapping
• Query results need to be tagged to XML format.

5
Our contributions

• We propose an efficient DOM-based linear data
  mapping algorithm, OXInsert, which shreds and
  composes input XML documents into relational
  tuples and inserts them into the relational
  database according to the schema generated by
  ODTDMap.
• We propose an efficient and linear SAX-based data
  mapping algorithm, SDM, which shreds and composes
  ordered XML documents into relational tuples and
  inserts them into the relational database
  according to the schema generated by ODTDMap.

6
Outline of the talk

• Main issues for data mapping
• Data mapping algorithm OXInsert
• Data mapping algorithm SDM
• Complete example
• Conclusions and future work

7
Main issues for data mapping

• Varying document structure. XML documents have
  varying structures due to the optional occurrence
  operators ?', ', and choice operator ' used
  in the underlying DTD, unlike relational tables
  which always have a fixed structure.
• Scalability.
• Preserve document order.

8
XML Tree

• Definition 4.1 (XML Tree) We model an XML
  document D as an XML element tree (XML Tree) T,
  in which nodes represent XML elements and edges
  represent parent-child relationships between XML
  elements. The XML Tree T is an ordered tree and
  its nodes can have attributes and values
  associated with them. The root of XML Tree T is
  denoted by T.root.

9
XML Tree (cont)

• For each element node e in T, we use the
  following notations

10
(No Transcript)
11
(No Transcript)
12
OXInsert time complexity

• Lemma 4.2 Each non-inlinable element e in XML
  Tree T is enqueued into Queue q exactly once, and
  q only contains non-inlinable elements.
• Lemma 4.3 Each XML element e, except the root
  element in XML Tree T is enqueued into queue r
  exactly once.
• Theorem 4.4 (Time Complexity) The time complexity
  of algorithm OXInsert is O(n), where DTD Graph G,
  Relational Schema R and Schema Mapping s are
  fixed and n is the total number of XML elements
  and attribute values in XML Tree T.

13
(No Transcript)
14
(No Transcript)
15
SDM time complexity

• Theorem 4.6 (Time complexity) The time complexity
  of algorithm SDM is O(n) where n is the number of
  elements and attribute values in the input XML
  document.

16
A complete example
17
XML Tree for xbib.xml
18
Tables for xbib.xml
19
Conclusions

• We identified several challenging issues for the
  data mapping problem and proposed two linear data
  mapping algorithms, OXInsert and SDM, based on
  two well-known XML parsers DOM and SAX,
  respectively.
• We compared their performance. Experimental
  studies showed that these algorithms are
  efficient and well scalable with respect to the
  size of input documents.

20
Future work

• Considering semantic integrity constraints during
  data mapping needs to be investigated