Re: brutally simple question - number of triggers on a table

> While not particularly fond of triggers, foreign keys are definitely
> mandatory. Always. No exceptions.

In a data warehouse, this is not true. RI constraints such as PK, UK, and FK constraints are themselves the exception.

RI constraints exist for the purpose of enforcing RI, plus a few ancillary roles like documentation, plus some Oracle-specific side purposes such as query rewrite integrity enforcement in materialized views.

The purpose of a data warehouse does not include enforcing either business rules or referential integrity. Its purpose is to accurately extract, transform, load, and present data provided from operational source systems.

This isn't to rationalize an expediency. Neither is RI enforcement irrelevant or inconvenient. Rather, RI enforcement is no more the responsibility of the data warehouse than law enforcement is the responsibility of plumbers. Simply not part of the job description.

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