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Re: Is it bad practice to use lists in a column of a record?
Posted by: Peter Brawley
Date: October 31, 2021 12:29PM

DDL and SQL are text. Images are usually not helpful. To preserve text formatting here, use BBCode code tags.

Re lists, we don't get to make up how a relational database works. Before we work with one, we need to familiarise ourselves with how they work, eg with a summary like https://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch01.pdf.

A fundamental premiss of relational databases is atomicity, one value per cell. A value is atomic if it will always be inserted and retrieved as all of itself. Relational databases depend upon this premiss. A list isn't atomic. So yes, lists in single cells are bad practice.

Is queryable text an exception to the rule of atomicity? No, a text or blob field is stored & retrieved as a unit.

Is a JSON column an exception? It's more a fudge. It does support lists, and as a fudge it pays the price---JSON queries in RDBMSs tend to perform poorly.

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Re: Is it bad practice to use lists in a column of a record?
October 31, 2021 12:29PM


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