Mastering PostgreSQL 9.6

Managing corrupted data pages

PostgreSQL is a very stable database system. It protects data as much as possible and has proven its worth over the years. However, PostgreSQL relies on hardware and a properly working filesystem. If storage breaks, so will PostgreSQL--there is not much you can do about it apart from adding replicas to make things more fail-safe.

Once in a while, it happens that the filesystem or the disk fails. But in many cases, the entire thing will not go south; just a couple of blocks are corrupted for whatever reason. Recently, we have seen that happening in virtual environments. Some virtual machines don't flush to disk by default, which means that PostgreSQL cannot rely on things being written to disk. This kind of behavior ...