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Cache Estimates

Several workloads impact the PostgreSQL buffer cache and the Operating System page cache in different ways.

Here is an attempt to track the real-life cases where the *_cost GUC are abused to make a workload perform well. Some hypothetical scenarios are also described to illustrate possible corner-case situation or common workloads.


Cached data may not be re-used vs Cached data may be re-used.

Query trash cache vs Query build cache vs Query use cache

Server is not dedicated to PostgrSQL vs server is dedicated.

Real-Life issues

Add Kevin case if possible.


One query to trash them all. (but the kernel is not stupid)

Known Patterns

Day vs Night workload

Small server, small usage.