HorizonDB cache hierarchy: RAM, NVMe SSD, and multi-AZ storage behind PostgreSQL (opens in new tab)

HorizonDB extends PostgreSQL with disaggregated storage, making it appear to developers like PostgreSQL while offering cloud-native high availability, elasticity, and performance. Performance metrics, especially I/O, can reveal differences due to additional components such as local caches and remote storage along the read/write paths. Three aspects can expose these internal workings at the PostgreSQL layer: Cache utilization, observable via EXPLAIN BUFFERS, comparing shared buffer hits with r...