(Extended) Entity Relationship

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1 03 - Database Design, UML and (Extended) Entity Relationship Modeling CS530 Database Architecture Models and Design Prof. Ian HORROCKS Dr. Robert STEVENS

2 In this Section Topics Covered Database Design Considerations UML and Database Design ER Design and UML Related Topics ER Design Lectures 4 and 5 slide 2 22/10/2004

3 Design Considerations slide 3 22/10/2004

4 Conceptual Design includes Operational Use Mini World Requirements collection & analysis Processing Requirements Database requirements DBMS Independent Conceptual design Conceptual schema (in a high level data model) Transaction Design DBMS independent Data model design DBMS specific Conceptual schema (in the data model of a specific DBMS Physical design Transaction Implementation Internal schema (for the same DBMS) Data Definition Language Statements slide 4 22/10/2004

5 Database Application Life Cycle S yste m D e fin itio n Design Im plem entation Loading/Data Conversion Application Conversion Te s tin g & V a lid a tio n Operation M onitoring & M aintenance slide 5 22/10/2004

6 Conceptual design & Data model requirements Conceptual design Complete understanding of database structure, semantics, constraints, relationships etc DBMS independent Stable description Database users and application users views; aids their understanding Communication with users Data model requirements Expressive Simple Minimal small number of basic concepts that are distinct and non-overlapping in meaning Diagrammatic Formal accurate & unambiguous CONFLICTING REQUIREMENTS slide 6 22/10/2004

7 Transaction Design Known transactions (applications) that will run on the database Database schema must include all information required by transactions Relative importance of transactions and expected rates of invocation important for performance tuning Identify input/output & functional behaviour: 3 categories 1. Retrieval display/reports 2. Update insert new data/modify old 3. Mixed Transactions can be used to encapsulate integrity constraints slide 7 22/10/2004

8 Transaction Design High level process specification technique data flow diagrams, process modelling etc Detailed design using programming techniques for loops, if statements etc Detailed design using set database operations Eight basic operations for updates on EER schema insert entity, modify, delete entity add, modify, remove relationship add and remove from class add and remove class slide 8 22/10/2004

9 Transaction environment Pre-defined canned transactions A free-for-all using SQL directly Chiefly On-Line Transaction Processing (OLTP) Chiefly Management Information System (MIS) Multi-user or single-user number of concurrent users peaks, worst case, and average potential conflicts locking, timestamps distributed transactions Integrity Checks as updates made in transactions batch run transaction slide 9 22/10/2004

10 On-Line Transactions ON-LINE DECISION SUPPORT TRANSACTION PROCESSING Inquiry & Analysis Real time Transactions Retrieval Intensive Update Intensive Ad Hoc Queries Pre-Defined Transactions Unpredictable Query Complexity Transaction Throughput Data Integrity High Availability slide 10 22/10/2004

11 Who is Using the Database? Users & Ease of Use Who is the target end-user for queries and/or update transactions User Interfaces Interfaces people software graphical forms-based SQL reports generated menu-based Task analysis other databases hardware organisational processes Work flows Views slide 11 22/10/2004

12 Housekeeping Backup & Archiving on-line or off-line backups size of backups incremental vs dump archiving strategy Security passwords permissions views slide 12 22/10/2004

13 Operational Considerations Scope complete flexibility with bells and whistles kernel activities Model choice hierarchical / network / relational / object-oriented /object-relational Software/Hardware Which database management system? Configuration: e.g Unix server and PC front-ends? slide 13 22/10/2004

14 Choice of DBMS Costs 1. Software acquisition cost 2. Maintenance cost 3. Hardware acquisition cost 4. Database creation & conversion cost 5. Personnel cost 6. Training cost 7. Operating costs Data model depends on: The structure and use of the data Familiarity of the system Available vendor services communication software data entry software design and monitoring tools etc slide 14 22/10/2004

15 UML - (E)ER slide 15 22/10/2004

16 EER vs. UML Terminology UML Class Diagram EER Diagram Class Entity Type Object Entity Attribute Attribute Domain Domain Structured Domain Composite Attribute Operation ~ [Derived Attribute] Association Relationship Type Link Relationship Instance Multiplicities Cardinality & Participation slide 16 22/10/2004

17 EER Diagram Overview slide 17 22/10/2004

18 EER to UML #1 slide 18 22/10/2004

19 EER to UML #2 slide 19 22/10/2004

20 Background slide 20 22/10/2004

21 Storage: Size and Volatility of data number of records (tuples) record (tuple) size growth potential volatility (growth/shrinka ge) temporary space requirements create table year (yearno number(1) primary key, yeartutorid number(4), yeartut_uk unique exceptions into bad_tutors using index not null constraint tut_fk foreign key (yeartutorid) references staff(staffid)) tablespace cags_course storage (initial 6144 next 6144 minextents 1 maxextents 5 pctincrease 5 pctfree 20); slide 21 22/10/2004

22 Performance Query Profile frequency of certain queries hit rate on relations certain relations used together selection attributes Update Profile dynamic or static hit rate of certain updates predictable pre-fetch strategies APPLICATION SPECIFIC must know about queries, transactions & applications analysing DB queries and transactions analysing expected frequency of invocation of queries and transactions analysing time constraints of queries and transactions analysing expected frequency of update operations slide 22 22/10/2004

23 Performance Measures Response time: how long will a query/update take? on average at peak times: worst case Transaction throughput: how many transactions can be processed per second/millisecond on average at peak times: worst case How long will a report on the whole database take? Data take-on Analytical & experimental approaches slide 23 22/10/2004

24 Benchmarks 1. Industry standard external view of product; samples performance on specific (simple) application; meant for comparison across vendors 2. Vendor identifying performance improvements evolve with product guide to development efforts & sales support 3. Customer-application for important performance critical applications vendors provided with benchmark by customer high cost for customer often rely on industry-standard measure slide 24 22/10/2004

25 Industry Standard Benchmarks significant disk input/output, moderate system and application execution time, and transaction integrity The Transaction Processing Performance Council (TPC) TPC-D: Debit/Credit Banking Application Performance Metrics: Throughput transactions per second (tps) Response time of transaction (transaction elapse time) Cost metric $/tps OLTP multiple on-line terminal sessions transaction arrival distribution. Wait time between requests is think time a wide range of functions, provided over small to large databases Not update-intensive Ad hoc queries Flexibility of query specification Wisconsin Designed to produce predictable results Performance Metrics: Response time of query (query elapse time) CPU & I/O utilisation Set Query average query throughput per minute & cost metric slide 25 22/10/2004

Practical Database Design Methodology and Use of UML Diagrams Design & Analysis of Database Systems

Practical Database Design Methodology and Use of UML Diagrams 406.426 Design & Analysis of Database Systems Jonghun Park jonghun@snu.ac.kr Dept. of Industrial Engineering Seoul National University chapter