Bypass PostgreSQL catalog overhead with direct partition hash calculations

PostgreSQL’s hash partitioning distributes rows across partitions using deterministic hash functions. When you query through the parent table, PostgreSQL must perform catalog lookups to route each query to the correct partition. This results in measurable overhead for high-throughput applications, especially if you decide to use multi-level partitioning schemes where PostgreSQL must traverse deeper catalog structures to identify the target partition. Let’s take a look at some findings on speeding up the part where you already know the partition key values.