Topic: fact-based analysis for database design

topics > computer science > database > Group: database model

database as a model of reality
database entities
database schema
facts as relationships between entities
information as facts


As an answer to his Data and Reality, Kent developed fact-based analysis. The important idea is to start by collecting the facts to be maintained by the database. These facts are then combined into records with entities replaced by symbolic references. The result is a normalized database. (cbb 1/90)
Subtopic: focus on facts up

Quote: to design a database, should focus on facts to be maintained by the database [»kentW1_1984]
Quote: first identify facts to be maintained and then aggregate facts into data records [»kentW1_1984]
Quote: in fact-based analysis, start with facts instead of entities; do not need to distinguish relationship from attribute [»kentW1_1984]

Subtopic: pseudo-records of actual entities up

Quote: in a pseudo-record, actual entities (e.g., employees) sit in fields of the record [»kentW1_1984]
Quote: initially, pseudo-records do not contain digital data and there is one record for each attribute of an entity [»kentW1_1984]
Quote: need to eliminate nonsymbol fields from pseudo-records to make them proper records [»kentW1_1984]
Quote: in conceptual modeling, relations are between objects instead of names of objects [»borgA1_1985]
Quote: a fact consists of identifying a relationship between surrogates [»kentW_1978]
Quote: with surrogates, a fact is an association of surrogates that correspond to objects in the fact [»kentW_1978]

Subtopic: merging pseudo-records up

Quote: when possible, a data record should aggregate all facts about an entity [»kentW1_1984]
Quote: instead of normalizing badly assembled records, should construct normalized records directly [»kentW1_1984]
Quote: merge pseudo-records when they have compatible keys [»kentW1_1984]
Quote: if a pseudo-record key allows zero participation, it can merge by padding with null values [»kentW1_1984]
Quote: in merging compound keys should only merge attributes of the same relationship [»kentW1_1984]

Subtopic: no duplicates up

Quote: duplicate rows do not represent distinct objects; a fact is a fact; avoid redundancy

Related Topics up

Topic: database as a model of reality (25 items)
Topic: database entities (12 items)
Topic: database schema (29 items)
Topic: facts as relationships between entities (22 items)
Topic: information as facts
(21 items)

Updated barberCB 6/04
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