Session7

Session7 - 1 Session-7: Object-Relational DBMS Cyrus...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

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

Unformatted text preview: 1 Session-7: Object-Relational DBMS Cyrus Shahabi 2 Motivation x Relational databases (2 nd generation) were designed for traditional banking-type applications with well-structured, homogenous data elements (vertical & horizontal homogeneity) and a minimal fixed set of limited operations (e.g., set & tuple- oriented operations). x New applications (e.g., CAD, CAM, CASE, OA, and CAP), however, require concurrent modeling of both data and processes acting upon the data. x Hence, a combination of database and software-engineering disciplines lead to the 3 rd generation of database management systems: Object Database Management Systems, ODBMS. x Note that a classic debate in database community is that do we need a new model or relational model is sufficient and can be extended to support new applications. 3 Motivation x People in favor of relational model argue that: s New versions of SQL (e.g., SQL-92 and SQL3) are designed to incorporate functionality required by new applications (UDT, UDF, ). s Embedded SQL can address almost all the requirements of the new applications. x Object people, however, counter-argue that in the above- mentioned solutions, it is the application rather than the inherent capabilities of the model that provides the required functionality. x Object people say there is an impedance mismatch between programming languages (handling one row of data at a time) and SQL (multiple row handling) which makes conversions inefficient. x Relational people say, instead of defining new models, lets introduce set-level functionality into programming languages. 4 Weaknesses of Relational Data Model x Poor representation of real world conceptual model s Usually the relational schema does not correspond to real world entities x Difficult to change schema without affecting the applications; e.g., Y2K x Semantic overloading s The same relation is used to represent entities as well as relationships x Poor support for integrity and business rules x Fixed number of attributes & all attribute values must be atomic x Limited operations x Difficult to handle recursive queries x Impedance mismatch (when SQL is embedded in PLs) s Type System mismatch, Evaluation Strategy mismatch x Poor navigational access x Short-lived transactions (strict locking and recovery mechanisms 5 Michael Stonebrakers Classification x Michael Stonebraker presents this four-quadrant matrix in the book entitled Object-Relational DBMSs: The Next Great Wave s This is a classification of both database applications and systems. 6 Lower-Left Quadrant x Those application that process simple data and require no query capability e.g. text processors (word, emacs) s Information has little internal structure....
View Full Document

Page1 / 30

Session7 - 1 Session-7: Object-Relational DBMS Cyrus...

This preview shows document pages 1 - 7. Sign up to view the full document.

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