> Therefore, a long lasting reader can prevent the "write-aside" updates from being copied to the database. Yes, this is abundantly documented. My question is whether a reader needs write access in order to make this effective. I can ask the question in a third way, because I really hope that we can get to the point: Can a process without write UNIX permission to a WAL database file in and directory prevent concurrent writers from checkpointing? This is a very precise question! Thank you very much in advance.