[estetlinus]

The lost art of normalizing databases. ”Why is the ARR so high on client X? Oh, we’re counting it 11 times lol”.

I would maybe throw in date as an key too. Bad idea?

[hilariously]

It depends on if you are doing OLTP (granular, transactional) vs OLAP (fact/date based aggregates) - dates are generally not something you'd consider in a fully normalized flow to uniqify records.

[estetlinus]

Makes sense. I’m an OLAP guy.

[hilariously]

Well you are in luck, if someone tells your to normalize you can tell them their source system can fuck right off.

[petalmind]

Frankly I don't think that overcounting is solved by normalizing, because it's easy to write an overcounting SQL query over perfectly normalized data.

I tried to explain the real cause of overcounting in my "Modern Guide to SQL JOINs":

https://kb.databasedesignbook.com/posts/sql-joins/#understan...

[mickeyp]

I'll go one further and say that if you're reaching for DISTINCT and you have joins, you may have joined the data the wrong way. It's not a RULE, but it's ALWAYS a 'smell' when I see a query that uses DISTINCT to shove away duplicate matches. I always add a comment for the exceptions.

[estetlinus]

Great read, thank you!