PostgreSQL Settings Calculator

shared_buffers sets the amount of memory PostgreSQL uses for shared memory buffers. The recommended starting point is 25% of total system memory. Unlike MySQL's buffer pool, PostgreSQL relies heavily on the OS page cache, so setting this too high can actually hurt performance.

effective_cache_size provides an estimate to the query planner of how much memory is available for disk caching. It includes both shared_buffers and OS file system cache. A good starting value is 75% of total system memory. This setting does not allocate memory — it only informs the planner.

work_mem sets the amount of memory used for sort operations and hash tables before writing to temporary disk files. A single complex query can use multiple units of work_mem simultaneously. Setting this too high with many connections can exhaust memory; too low causes frequent disk spills.

PostgreSQL creates a new process for each connection, using about 10MB of memory each. Connection poolers like PgBouncer or pgpool-II multiplex many client connections over fewer server connections, dramatically reducing memory usage and improving performance.

random_page_cost tells the query planner the estimated cost of a non-sequential disk page fetch. For SSDs and NVMe drives, set this to 1.1 (close to sequential cost). For HDDs, the default of 4.0 is appropriate. Incorrect values can cause the planner to choose suboptimal query plans.