PostgreSQL, Second Edition

The ARC Buffer Manager

It's important to keep a few points in mind when you're trying to tune a PostgreSQL database. First, the shared buffer cache is shared. All of the examples in this chapter were built using a single-session database—if you try to reproduce these experiments, be sure you're the only one using the database or your results will vary widely. Second, the important part of a buffer management scheme isn't the part that determines what goes into the cache, it's the part that determines what gets thrown out of the cache. When PostgreSQL reads data from a table, it first checks to see if the required page is in the cache. If PostgreSQL finds it in the cache, it stops looking. If the required page isn't in the cache, PostgreSQL must ...