connection-pooling

Use when reasoning about how an application manages its database connections: why every connection has a server-side cost, the difference between application-level pools (HikariCP, pgx pool, node-postgres Pool) and proxy-level pools (PgBouncer, Pgpool, ProxySQL), the three PgBouncer modes (session, transaction, statement) and their feature compatibility, the canonical pool-sizing math (Little's Law applied to database concurrency; Wooldridge's analyses), the failure modes (connection exhaustion, hot-loop reconnects, prepared-statement breakage under transaction pooling, idle-in-transaction leaks), and the diagnostic procedure when a workload is contending on connections instead of query work. Do NOT use for query-level performance (use query-optimization), for index design (use indexing-strategy), for read/write replica routing (use replication-patterns), or for cross-shard query coordination (use sharding-strategy).