> Why isn't the OS caching the disk blocks, and why isn't Postgres using the cached data?
It does, but the cache is for each connection/job. They are not shared.
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Melvin Davidson
Maj. Database & Exploration Specialist
Universe Exploration Command – UXC
Employment by invitation only!
That is simply not true: shared_buffers have this name for a reason. What’s not shared is work_mem used for sorting, etc…
Also OS cache is shared too.
Regards,
Igor Neyman