# Understanding Why OS RAM and Postgres Buffer Cache Compete

Page: https://stenobird.com/podcast/the-good-tech-companies-6882802/understanding-why-os-ram-and-postgres-buffer-cache-compete
Text version: https://stenobird.com/podcast/the-good-tech-companies-6882802/understanding-why-os-ram-and-postgres-buffer-cache-compete.md
Podcast: [The Good Tech Companies](https://stenobird.com/podcast/the-good-tech-companies-6882802)
Published: 2026-05-27T08:30:48+00:00
Episode link: https://share.transistor.fm/s/0f0f3657
Audio file: https://media.transistor.fm/0f0f3657/5bd31d8e.mp3
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JSON: https://stenobird.com/v1/public/podcasts/the-good-tech-companies-6882802/episodes/understanding-why-os-ram-and-postgres-buffer-cache-compete
Duration seconds: 495

## Resource

This story was originally published on HackerNoon at: https://hackernoon.com/understanding-why-os-ram-and-postgres-buffer-cache-compete . Learn how PostgreSQL double buffering wastes RAM, increases latency, and hurts query performance — plus the 25% shared_buffers rule to fix it. Check more stories related to programming at: https://hackernoon.com/c/programming . You can also check exclusive content about #postgresql-double-buffering , #postgresql-shared_buffers , #pg_buffercache-analysis , #postgres-p95-latency , #postgresql-os-page-cache , #postgresql-memory-tuning , #effective_cache_size-tuning , #good-company , and more. This story was written by: @tigerdata . Learn more about this writer by checking @tigerdata's about page, and for more stories, please visit hackernoon.com . Many PostgreSQL performance issues aren’t caused by too little RAM, but by allocating memory to the wrong layer. Postgres and the OS both cache the same data independently, creating a “double buffering” problem that wastes memory and increases latency. This guide explains how shared_buffers and the OS page cache interact, why the 25% shared_buffers rule matters, how to diagnose cache pressure with pg_buffercache, and when tuning stops helping because the dataset itself has outgrown memory.

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