2_RDBMS_Overview - Distributed Database Systems RDBMS Overview 605.741 David Silberberg Data Structures Covered in the Course Relational model The

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Distributed Database Systems RDBMS Overview 605.741 David Silberberg
Background image of page 1

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

View Full DocumentRight Arrow Icon
D. Silberberg Distributed Database Systems RDBMS Overview 2 Data Structures Covered in the Course • Relational model – The relational model is a popular model for structured data – It is probably the most understood model – Many algorithms exist in relational database management systems that can be augmented to distributed systems – There is not the same level of support for other database models • Other data models – XML query management systems – in their infancy – Flat-file, Excel spreadsheets – Graphs – Knowledge bases (OWL, triple stores, etc.)
Background image of page 2
D. Silberberg Distributed Database Systems RDBMS Overview 3 Why are RDBMS Systems Popular? • Simple data structures – Rows, columns – Simple data items • Solid model – Foundation for consistency – Normalization eliminates data anomalies – Database can be maintained with integrity rules • Set-oriented data manipulation – Non-procedural – Relational algebra - set theory (SQL & QUEL) – Relational Calculus - logic (QBE)
Background image of page 3

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

View Full DocumentRight Arrow Icon
D. Silberberg Distributed Database Systems RDBMS Overview 4 Definitions and Concepts Database models some real life concept and captures actual data that represents some state of real life Relational database is a database modeled by relations Relation R defined over n sets D 1 , D 2 , … D n where D i represents some domain. n-tuple (tuple) is a set < d 1 , d 2 , …, d n > where d 1 ε D 1 , d 2 ε D 2 , …
Background image of page 4
D. Silberberg Distributed Database Systems RDBMS Overview 5 Example Relation and Domains • R is a set of 0 or more n-tuples (not necessarily distinct) • MFG( manufacturer, state ) –D 1 is set of all potential manufacturers 2 is a set of all 50 states –d 1 is any member of D 1 (i.e., Proctor & Gamble, McCormick Spice, etc.) 2 is any member of D 2 (i.e., OH, MD, etc.)
Background image of page 5

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

View Full DocumentRight Arrow Icon
D. Silberberg Distributed Database Systems RDBMS Overview 6 Keys Superkey - nonempty subset of relation's attributes that uniquely defines each tuple • Examples: – CUST(cust_no, cust_name, cust_address) • key is (cust_no) – ORDER(cust_no, part_no, quantity) • key is (cust_no, part_no) – PART: (part_no, part_name, manufacturer, cost) • key is (part_no) – MFG: (manufacturer, owner) • key is (manufacturer)
Background image of page 6
D. Silberberg Distributed Database Systems RDBMS Overview 7 Candidate Keys Candidate keys are minimal sets of attributes that uniquely define a row
Background image of page 7

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

View Full DocumentRight Arrow Icon
Image of page 8
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 / 30

2_RDBMS_Overview - Distributed Database Systems RDBMS Overview 605.741 David Silberberg Data Structures Covered in the Course Relational model The

This preview shows document pages 1 - 8. Sign up to view the full document.

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