Ring buffers are a widely used data structure in PostgreSQL, primarily for efficient data lookup and management during various internal operations, such as reading table data. For example, during the ANALYZE operation, PostgreSQL creates a ring buffer with a default size of 256 kB to load table data. This approach provides a dedicated temporary buffer for the operation, preventing the eviction of pages from the buffer pool, which could negatively affect the database's cache hit ratio.

However, in some cases, the default ring buffer size may not be sufficient for optimal performance. To enhance the efficiency of VACUUM or ANALYZE operations, you can increase the ring buffer size by tuning the vacuum_buffer_usage_limit configuration parameter or by passing the BUFFER_USAGE_LIMIT option to the ANALYZE command at runtime. Since this operation is I/O-bound, ensure your disk has adequate capacity to handle the increased load.

The vacuum_buffer_usage_limit and BUFFER_USAGE_LIMIT options were introduced in PostgreSQL 16, and they have quickly become some of my favourite performance features.