0085 — synchronous_commit=local is not measured

Context. synchronous_commit has five levels; besides on and off there is local, which relaxes only the wait for a synchronous standby, not the local WAL flush.

Decision. Do not measure local. On a single node with no synchronous standby, on, local, remote_write, and remote_apply all behave identically as “wait for local flush”; only off skips the fsync, so local would measure as on.

Consequences. A real local measurement would require standing up a streaming replica, which is out of scope for a measure-only phase. If replication is ever added, local becomes a distinct point worth measuring.