Automatic Generation of SQLX View Definitions from ORA-SS Views

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Automatic Generation of SQLX View Definitions from ORA-SS Views

Yabing Chen, Tok Wang Ling, Mong Li Lee

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Outline

Introduction Preliminaries Generating SQLX Query Definitions From

ORA-SS Views Conclusion

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Introduction

XMLThe dominant standard for exchanging data

on the Internet XML Views

Exploit the potential of XMLSecure the source dataProvide an application-specific view

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Introduction (cont.)

Main related work In all these works, the original data are in RDB

SilkRoute [1] [2] Two declarative language RXL and XML-QL to define and

query the views over relational data XPERANTO [3] [4]

uses a canonical mapping to create a default XML view from relational data

Oracle [7], IBM DB2 [8] & SQL Server [6] provide the ability to export relational data to materialized XML

views

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Disadvantage of the main related work Ignore semantic information in source data

For example, ignore the difference between object class, attribute and relationship in schema

Cannot check the validity of designed viewsDifficult to use query languages to define

views Proprietary language or XQuery

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Our approach for XML views The original data are in XML and then stored in

ORDB Design valid XML Views [9]

Based on a semantically rich model - ORA-SS Use query operators, such as selection, drop, swap, join,

etc. Support more flexible views than related work, such as

swapping views Transform the designed views into SQLX queries on

ORDB (this paper)

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Preliminaries ORA-SS data model

Three concepts: Object class, attribute and relationship type An object-relational storage for XML

Store each object class with all its attributes into a nested relation Store each relationship type with all its attributes into a nested relation

SQLX syntax An emerging part of the ANSI and ISO SQL standard XMLELEMENT

Generate an XML element XMLAGG

Produce a forest of XML elements from a collection of individual elements

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Preliminaries – Example

em p lo y ee

p r o jec t

en o

jn o

p r o g r es s

p e , 2 , 1 :n , 1 :n

p e

en am e

jn am e

Object relations: project (jno, jname); employee (eno, ename); Relationship relations: pe (jno, eno, progress);

Object-relational storage schema

An ORA-SS source schema

Select xmlelement(“employee_list”, xmlagg( xmlelement(“employee”, xmlattributes(e.eno, e.ename) ) ) )From employee e

Query: List all employees

<employee_list> <employee eno=“e01” ename=“david”/> <employee eno=“e02” ename=“paul”/></employee_list>

Result:

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Generate SQLX queries from ORA-SS views

Main idea An object in the view is determined by some

particular objects in the view through the relationship types involved.

m em b er

p r o jec t

m n am e

jn o

jo t_ tit le

jn am e

p u b licat io n

p n o p u b _ t it le

jm , 2 , 1 :n , 1 :n

m p , 2 , 1 :n , 1 :n

publication is determined by member through relationship type mp publication has nothing to do with project

member is called the Determined Object Class (DOC) of publication

mp is called the Determined Relationship Type (DRT) of publication

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Generate SQLX queries from ORA-SS views

Main idea (cont.) Identify relationship types in the views

Original relationship in the source schema Derived relationship by projecting existing relation in the ORDB Derived relationship by joining existing relations in the ORDB

Drop supplier

s u p p lie r

p r o jec t

jn am e

p ar t

s p j,3,1:n ,1:ns n o

p n o

p r ic e

s p j

p s

em p lo y ee

en o en am e p r o g r es s

je

p s , 2, 1:n , 1 :n

s n am e

p n am e

f ac to r y

f n o f n am e

s f ,2 ,1 :n ,1 :n

jn o q ty je ,2,1:n ,1:n

*

em ail

p ar t

p r o jec t

jn am e

p j,2 ,1 :n ,1 :np n o

p j

p n am e

f ac to r y

f n o f n am e

p f ,2 ,1 :n ,1 :n

jn o to ta l_ q ty

em p lo y ee


je ,2 ,1 :n ,1 :n

je

*

em ail

Source schema View schema

Object relations: supplier (sno, sname); part (pno, pname); factory (fno, fname); project (jno, jname); employee (eno, ename, (email)*);

Relationship relations: ps (pno, sno, price); sf (sno, fno); spj (sno, pno, jno, qty); je (jno, eno, progress);

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General rules for generating SQLX queries from ORA-SS views Rule Gen 1 for object class along with its

attributes Case 1: DRT is original relationship Case 2: DRT is derived relationship by projecting

existing relation Case 3: DRT is derived relationship by joining existing

relations Rule Gen 2 for attributes

Case 1: original relationship attributes Case 2: derived relationship attributes Case 3: multi-valued attributes

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Rule Gen 1 (for object class in the view)

Case 1: If the DRT is an original relationship type from the source schema, then Directly use the original relationship type to generate the where

conditions in the where clause.

p ar t

p r o jec t

jn am e

p j, 2 ,1 :n ,1 :np n o

p j

p n am e

f ac to r y

f n o f n am e

p f ,2 ,1 :n ,1 :n

jn o to ta l_ q ty

em p lo y ee


je ,2 ,1 :n ,1 :n

je

*

em ail

Select xmlagg( xmlelement(“employee”, xmlattributes(e.eno, e.ename)))From employee e, jeWhere e.eno = je.jno and je.jno = j.jno

SQLX expression for employeeemployee (eno, ename, (email)*);je (jno, eno, progress);

e.g. je

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Rule Gen 1(cont.) Case 2: if the DRT is a derived relationship type by projecting

existing relation in the ORDB, then Replace the derived relationship type with its corresponding original

relationship type in the where clause

p ar t

p r o jec t

jn am e

p j,2 ,1 :n ,1 :np n o

p j

p n am e

f ac to r y

f n o f n am e

p f ,2 ,1 :n ,1 :n

jn o to ta l_ q ty

em p lo y ee


je ,2 ,1 :n ,1 :n

je

*

em ail

Select xmlagg( xmlelement(“project”, xmlattributes(j.jno, j.jname)))From project j, pjWhere pj.jno = j.jno and pj.pno = p.pno

Select xmlagg( xmlelement(“project”, xmlattributes(j.jno, j.jname)))From project j, spjWhere spj.jno = j.jno and spj.pno = p.pno

pj = spj [p, j]

spj (sno, pno, jno, qty)project (jno, jname)

e.g. pj

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Rule Gen 1(cont.)

Case 3: If the DRT is a derived relationship type by joining existing relations in the ORDB, then Rewrite the where condition with the DRT’S corresponding original

relations in the where clause

p ar t

p r o jec t

jn am e

p j,2 ,1 :n ,1 :np n o

p j

p n am e

f ac to r y

f n o f n am e

p f ,2 ,1 :n ,1 :n

jn o to ta l_ q ty

em p lo y ee


je ,2 ,1 :n ,1 :n

je

*

em ail

Select xmlagg( xmlelement(“factory”, xmlattributes(f.fno, f.fname) )From factory f, pfWhere f.fno = pf.fno and pf.pno = p.pno

Select xmlagg( xmlelement(“factory”, xmlattributes(f.fno, f.fname) )From factory f, ps, sfWhere f.fno=sf.fno and sf.sno=ps.sno and

ps.pno=p.pno

Replace pf by ps and sf in ORDB

factory (fno, fname);ps (pno, sno, price); sf (sno, fno);

e.g. pf

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Rule Gen 2 (For relationship attributes) Case 1: If a single valued attribute A belongs to R and R is an

original relationship type from source schema, then generate an xmlelement function for the attribute A:

xmlelement(“A”, R.A)

p ar t

p r o jec t

jn am e

p j,2 ,1 :n ,1 :np n o

p j

p n am e

f ac to r y

f n o f n am e

p f ,2 ,1 :n ,1 :n

jn o to ta l_ q ty

em p lo y ee


je ,2 ,1 :n ,1 :n

je

*

em ail

View schema

Select xmlagg( xmlelement(“employee”, xmlattributes(e.eno, e.ename), xmlelement(“progress”, je.progress)))From employee e, jeWhere e.eno = je.jno and je.jno = j.jno

SQLX expression for employee

e.g. progress

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Rule Gen 2 (cont.) Case 2: If an attribute A belongs to R and R is a derived relationship

type by projecting an original relation R’ in the ORDB, then Generate an xmlelement function for the attribute A with agg function:

xmlelement(“A”, agg(R’.A)) Append a group by clause for the agg function (e.g. total_qty)

p ar t

p r o jec t

jn am e

p j,2 ,1 :n ,1 :np n o

p j

p n am e

f ac to r y

f n o f n am e

p f ,2 ,1 :n ,1 :n

jn o to ta l_ q ty

em p lo y ee


je ,2 ,1 :n ,1 :n

je

*

em ail

View schema

Select xmlagg( xmlelement(“project”, xmlattributes(j.jno, j.jname), xmlelement(“total_qty”, sum(spj.qty))))From project j, spjWhere spj.jno = j.jno and spj.pno = p.pnoGroup by j.jno, j.jname

SQLX expression for project

(e.g. total_qty)

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Rule Gen 2 (cont.)

Case 3: If an attribute A is a multi-valued attribute in the ORDB, then Generate an sub query to extract the value of A

p ar t

p r o jec t

jn am e

p j,2 ,1 :n ,1 :np n o

p j

p n am e

f ac to r y

f n o f n am e

p f ,2 ,1 :n ,1 :n

jn o to ta l_ q ty

em p lo y ee


je ,2 ,1 :n ,1 :n

je

*

em ail

View schema

Select xmlagg( xmlelement(“employee”, xmlattributes(e.eno, e.ename) (select xmlagg(xmlelement(“email”, email)) from table(e.email) ))From employee e, jeWhere e.eno = je.jno and je.jno = j.jno

SQLX expression for employee

(e.g. email)

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The SQLX query for the whole view example

Select //generate root & part xmlelement(“root”, xmlagg( xmlelement(“part”, xmlattributes(p.pno, p.pname), (Select // generate factory xmlagg( xmlelement(“factory”, xmlattributes(f.fno, f.fname) ) ) From factory f, ps, sf Where f.fno = sf.fno and sf.sno = ps.sno

and ps.pno = p.pno ), (Select // generate project xmlagg( xmlelement(“project”, xmlattributes(j.jno, j.jname), xmlelement(“total_qty”, sum(spj.qty)), (Select xmlagg( // generate employee xmlelement(“employee”, xmlattributes(e.eno,

e.ename),

(select xmlagg(xmlelement(“email”, email)) from table(e.email) ) xmlelement(“progress”, je.progress) ) ) From employee e, je Where e.eno = je.jno and je.jno = j.jno ) ) ) From project j, spj Where j.jno = spj.jno and spj.pno = p.pno Group by j.jno, j.jname ) ) )From part p

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Algorithm

Use a deep-first search algorithm to generate the SQLX query for the ORA-SS view

1. Generate the SQLX query based on the view schema (with derived relationship types, etc)

2. Replace each derived relationship type by using the corresponding relations in the ORDB

For swapping and selection relationship types, They refers to the same relations in the ORDB For selection operator, append the selection

condition in the SQLX query

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Conclusion

Main contribution An approach to automatically generate SQLX query

definitions of ORA-SS views Remove the need for users to manually write complex SQLX

view definitions Main difference between this paper and ER’03

paper [10] The storage of XML data

In ER’03: Text file In this paper: ORDB

Semantics of ORA-SS views (relationship in the views) In ER’03: Do not utilize the semantics In this paper: Utilize the semantics (e.g. DRT & DOC)

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References

[1]M. Fernandez, W. Tan, D. Suciu, “Efficient Evaluation of XML Middleware Queries”, ACM SIGMOD, pp. 103-114, 2001.

[2] M. Fernandez, W. Tan, D. Suciu, “SilkRoute: Trading Between Relations and XML”, World Wide Web Conference, 1999.

[3] M. Carey, J. Kiernan, J. hanmugasundaram, et. al., “XPERANTO: A Middleware for Publishing Object-Relational Data as XML Documents”, VLDB, pp. 646-648, 2000.

[4] M. Carey, D. Florescu, Z. Ives, et. al., “XPERANTO: Publishing Object-Relational Data as XML”, WebDB Workshop, 2000.

[6] Microsoft Corp. http://www.microsoft.com/XML.[7] Oracle Corp. http://www.oracle.com/XML.[8] IBM Corp. http://www.ibm.com/XML.[9] Y.B. Chen, T.W. Ling, M.L. Lee, “Designing Valid XML Views”, ER Conference, 2002[10] Y.B.Chen, T.W.Ling, M.L.Lee, “Automatic Generation of XQuery Definitions from ORA-SS

Views”, ER Conference 2003.[11] Y.Y.Mo, T.W.Ling, “Storing and Maintaining Semistructured Data Efficiently in an Object-

Relational Database”, WISE Conference, 2002. [12] SQLX. http://www.sqlx.org