chapter15 - Chapter 15 Database Interoperability 15.1...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 15 Database Interoperability 15.1 Database Integration Integration Process (1) Schema translation, (2) Integration Levels of data views (1) Component database schemas (2) Common intermediate canonical representation (3) Global conceptual schema Example 15.1 Site1: a relational database EMP(ENO , ENAME, TITLLE) PROJ(PNO , PNAME, BUDGET, LOC, CNAME) 1 Database 1 Database 2 Database 3 Translator 1 Translator 2 Translator 3 InS 1 InS 2 InS 3 Integrator GCS
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ASG(ENO, PNO , RESP, DUR) PAY(TITLE , SAL) Site2: an E-R database 15.1.1 Schema Translation Global conceptual schema should be semantic rich enough to cover each of the local schema semantics Example 15.2 Integrate the two sites of example 15.1. (1) E-R model is selected as the canonical model since it is 2 ENGINEER Engineer No Engineer Name Title Salary WORKS IN Duration Responsibility PROJECT CONTRACTED BY Project No Bugdet Location Project Name Contract Date CLIENT Clinet Name Address N 1 N 1
Background image of page 2
more expressive (2) Only translate site1 into E-R model (site2 already in E-R model) Difficulties (1) Entity determinations—which relations represent the entities , which represent the relationship s (2) Type determinations of relationships— many to many , one to one , or one to man y Remark : reasoning from the database dictionary ( primary key , foreign key , or other constraints) Two E-R representations of Site1 The translation is not unique (a) 3 EMP ENO ENAME RESP ASG DUR PROJ PNO PNAME BUDGET CNAME LOC PAYMENT PAY TITLE SAL N M N 1
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
(b) 15.1.2 Schema Integration Integrating procedures (1) identifying the inter-relationship components among local databases (2) selecting the best representations for the global conceptual schema (3) integrating the components of each intermediate schema Integration methodologies (1) binary: ladder fashion (figure a), balanced fashion (figure b) (2) n-ary: one-pass integration (figure c), iterative nary integration(figure d) 4 EMP ENO ENAME RESP ASG DUR PROJ PNO PNAME BUDGET CNAME LOC TITLE SAL N M
Background image of page 4
Remark : binary integration is easy for implementation than n- ary Homogenization —determine the structural and semantic conflict problems Important semantic conflicts are naming problems : synonyms and homonyms
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/23/2009 for the course DBST 663 taught by Professor Tba during the Spring '09 term at MD University College.

Page1 / 16

chapter15 - Chapter 15 Database Interoperability 15.1...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online