Friday, April 5, 2024

TLC: RDM & "ARBITRARY DATA TYPES"



Note: I am working on entirely new papers (not re-writes) in the PRACTICAL DATABASE FOUNDATIONS series. I have already published two:

THE FIRST NORMAL FORM - A DEFINITIVE GUIDE

PRIMARY KEYS - A NEW UNDERSTANDING

available for ordering from the PAPERS page, and two more:

RELATIONAL DATABASE DOMAINS: A DEFINITIVE GUIDE

DATABASE RELATIONS: A DEFINITIVE GUIDE

are in progress.

In the process I am coming across industry common and entrenched "pearls" that I am using for my "What's Right/Wrong with this Database Picture, or "Setting Matters Straight" (SMS), and "To Laugh or Cry" (TLC) posts on Linkedin. I do these posts to enable the few thinking database professionals left realize how scarce foundation knowledge is, and to illustrate fallacies that abound in the industry, of which they are unaware, and which the papers are intended to dispel.

Time permitting, I may specify those fallacies in brief posts that I set straight in the papers, such that those thinking professionals can test their knowledge and decide whether the papers are a worthy educational investment.


Here comes the first, a TLC I just posted on LinkedIn:

 

 “The company was using a [SQL] RDBMS . . . to handle data transactions for its trading applications. However, the applications required arbitrary data types, which is nearly impossible for relational systems, according to experts.”


which contains three fallacies--can you identify them before you proceed?

Wednesday, February 7, 2024

NEW PAPER: PRIMARY KEYS - A NEW UNDERSTANDING



 New, completely re-written. Available to order here



Table of Contents

Series Preface

Abstract

Introduction

1. Entities, Properties, Names, and Identification

2. Relational Representation

3. Relational Keys

    3.1. Kinds of Keys

           3.1.1. Candidate, Primary and Alternate Keys

           3.1.2. Natural and Surrogate Keys

4. Formal Primary Key Mandate

5. Primary Key Designation

6. Keys and Constraints

7. Keys and Performance

   7.1. Keys and Indexes

Conclusion

References

Appendix A: Keys in SQL

Appendix B: Duplicates and Consequences

B1. Duplicate Interpretation

B2. Duplicates in SQL

      B2.1. Duplicates and Correctness

      B2.2. Duplicates and Query Nestability

      B2.3. Language Redundancy & Duplicates

      B2.4. Duplicates and Performance Optimization

      B2.5. Duplicate Removal

Monday, February 5, 2024

METALOGICAL PROPERTIES Part 2: Assertion Predicate



In Part 1 we introduced in the conceptual model (CM) the metalogical designation property. It represents—in the absence of known shared defining properties of an entity type, the designation by a group's definer that an entity identifier (aka assigned name) or property value is a member of the group. Such a group is not a group of entities, but a group of name and property values. In the logical model (LM), it is formalized as a designation predicate (DP) and defines a domain.

In Part 2, we introduce the metalogical assertion property. It represents the assertion by an authorized database user that a specific entity, represented by a tuple, either does or does not correspond to an actual entity in the real world.

Tuesday, January 9, 2024

METALOGICAL PROPERTIES PART 1: Designation Property



 with David McGovern

One purpose of our contributions here is to suggest a vocabulary that avoids confusion not just within the formal logical level, but also between conceptual and logical terminologies, which is widespread in the industry and is exacerbated by limitations of natural language (NL). We use the following terminology in our approach to conceptual modeling:

  • Objects are:

- Primitive (basic entities);

- Compound:

  - groups of related entities;

  - multigroups (groups of related groups);

  • Properties are:

- Individual (of basic entities);

- Collective:

  - Of groups: relationships among entities within a group;

  - Of multigroups: relationships among groups within a multigroup.

 

Note:  It is a McGoveran insight that relationships between objects at a lower aggregate level are properties of the object at the higher aggregate level which the former comprise (LOGIC FOR SERIOUS DATABASE FOLK, forthcoming; see draft chapters) http://www.alternativetech.com/ATpubs_dir.html For classification of properties as first, second, third and fourth order (1OP, 2OP, 3OP and 4OP) see RELATIONSHIPS AND THE RDM Parts 1-3. https://www.dbdebunk.com/2023/03/relationships-and-rdm-v2-part-1.html All such properties can be expressed logically in a FOPL-based relational data sublanguage as constraints, which is beyond the scope of this discussion.

Wednesday, November 22, 2023

HAPPY HOLIDAYS!



Due to: 

 

1. Taking care of some health issues that have accumulated (not getting any younger);

2. Concentration on the Israel-Hamas War;

3. Effort to update old papers and write new ones;

4. Much needed rest and the holidays.

 

I am taking the remaining of the year off and will re-start my contributions in January.

 

Wishing you and yours season's greetings and happy holidays!







Friday, October 13, 2023

EVERYBODY THINK THEY KNOW FIRST NORMAL FORM, BUT NOBODY DOES



“I have read this article in an effort to boost my academic knowledge on data modeling a bit and still have no idea what this academic author wanted to say. Apparently First Normal Form (1NF) doesn't get enough respect and then proceeds to talk about Non-First Normal Form (NFNF). But what about First Normal Form (1NF) damnit.”

By sheer chance this was posted on LinkedIn just after I published my new paper The First Normal Form: A Definitive Guide.

PRACTICAL DATABASE FOUNDATIONS

FIRST NORMAL FORM

A DEFINITIVE GUIDE

(September 2023)

Fabian Pascal

 

Table of Contents

 Introduction

1.      The Normal Form

2.      The First Normal Form

3.      Domain Decomposability & Atomicity

4.      1NF & Tables

5.      SQL & 1NF

5.1.     Repeating Groups & Repeated Attributes

5.2.   Information Principle & SQL
 

Sunday, September 17, 2023

DBDEBUNK REFRESH



After 23+ years DBDebunk.com has undergone a slight refresh. Here is an outline of the changes.

1. The BOOKS and PAPERS are now unified into one PUBS page from which my papers and self-published books can be ordered. There are two paper series:

  • Understanding the Real RDM: reviews and analysis of some Codd's published papers 1969-85 in the spirit of McGoveran re-interpretation of his work--distinct from that dominant in the industry.
  • Practical Database Foundations: shorter papers about narrower aspects of the RDM that are abused, misused and ignored in the industry.

Some papers will be brought up to date/re-written and new ones will be published.

2. The recommended books links from the BOOKS page have been moved to the LINKS page.

3. The FUNDAMENTALS page was replaced by a SEARCH page that contains a newly compiled data and relational fundamentals comprehensive dictionary of terms to be maintained on a regular basis. It includes abbreviations/acronyms to be used as labels for searching. Use the page as a reference in conjunction with the labels to compensate partially for a limitation of the Blogger labels facility.

4. Labels now exist only for the search terms that have known abbreviations  or acronyms. The SEARCH page should be used to identify which terms have labels and those that do not must be used with the Blogger search facility (see details on ABOUT page).


Any problems, comments, suggestions, questions, or support are welcome--drop me an email.


 

 

 

 

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