5 advanced PostgreSQL features I wish I knew sooner

5 months ago by marmelab to c/postgresql

GENERATED columns, EXCLUDE constraints, DISTINCT ON, Foreign Data Wrappers... PostgreSQL has powerful features you might not know about. Here are my favorites.

A few months ago, I struggled with a planning system. I needed to ensure that no 2 plans could overlap for the same period. My first instinct was to write application-level validation, but something felt off. I thought to myself that surely PostgreSQL had a better way.

Turns out, PostgreSQL is packed with a bunch of underrated (and often simply overlooked) features that can save you from writing complex application logic:

  1. EXCLUDE constraints: To avoid overlapping time slots

  2. CHECK constraints: For validating data at the source

  3. GENERATED columns: To let the database do the math

  4. DISTINCT ON: Cleaner than a GROUP BY with subqueries

  5. FILTER: To add a condition directly on the aggregate

Even after years of using it, I still discover features that make me question why I ever wrote complex application logic for things the database could handle natively.

I wrote an even more detailed version with examples (in case anyone thinks this isn't long enough lol)

Are there any other advanced PostgreSQL features I should know about?

BrilliantantTurd4361 2 points 5 months ago

DISTINCT ON is not an aggregate like group by; it allows you to select the first row matching the distinct clause given the ordering. It IS super useful!

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