Chapter 12

Question 1

what are the Challenges with Physical distribution?

Answer 1

Addressing data across the globe, assessing data in different schemas, optimizing distributed queries

Question 2

what are the Challenges of logical distribution?

Answer 2

Maintaining consistency among redundant data, provide metadata to enable data localization, detect and resolve duplicates, detect and resolve data inconsistencies and conflicts

Question 3

What is the major problem of integration?

Answer 3

autonomy is the major problem of integration.

Question 4

Technical heterogeneity:

Answer 4

communication protocols (http, soap,…); exchange formats (binary, text, xml…); APIS (jdbc, odbc,…); query mechanisms; query language

Question 5

Mention six types of heterogeneity:

Answer 5

Data Model Heterogeneity:
Technical heterogeneity
Syntactic heterogeneity
structural heterogeneity
schematic heterogeneity
semantic heterogeneity

Question 6

what are the Two architectural approaches to achieve data integration?

Answer 6

• materialized integration (replication, data warehousing)

* virtual integration (federated DBMS, multi-database systems)

Question 7

Distribution controlled by DBMS (distributed transaction processing)

Answer 7

• single select statement can access tables in different data sources
• virtual integration
• degrees of transparency

Question 8

Materialized and virtual integration

Answer 8

Materialized: ETL (Extract, transfor, load)
Virtual: wrappers