How to slice Postgres tables so queries don’t choke

Postgres lets you split big tables into partitions — rows with the same date, the same region, whatever. The database then prunes away partitions it doesn’t need, so queries scan less data. It’s not magic, but it’s the cheapest way to keep a table from becoming a bottleneck.

TLDR DevOps walks through how partition pruning works under the hood. The gist: you define a partition key, and the planner uses that key to skip partitions that can’t possibly match your WHERE clause. If you’re running analytics on a table that’s grown to millions of rows, this is usually the first lever you pull before reaching for a full rewrite.

The post also touches on trade-offs — partition maintenance, the cost of too many small partitions, and when pruning just doesn’t kick in because the planner can’t prove a partition is irrelevant. Worth a read if you’re wrestling with a table that’s gotten too big to manage in one shot.

The source is a dev newsletter, so the tone is practical, no fluff. TLDR DevOps is run by Dan Luu, who writes for engineers who need to ship.

Why this matters for us: when apps built by Brown devs slow to a crawl because the database can’t keep up, this is the kind of low-level fix that keeps the hustle running without a full rebuild.