On 2018-03-07 23:34:37 -0500, Tom Lane wrote: > Craig Ringer <cr...@2ndquadrant.com> writes: > > As I understand it, because we allow multiple Pg instances on a system, we > > identify the small sysv shmem segment we use by the postmaster's pid. If > > you remove the DirLockFile (postmaster.pid) you remove the interlock > > against starting a new postmaster. It'll think it's a new independent > > instance on the same host, make a new shmem segment and go merrily on its > > way mangling data horribly. > > Yeah. If we realized that the old shmem segment was associated with this > data directory, we could check for processes still attached to it ... but > the lock file is exactly where that association is kept.
I'd somehow remembered that we just took the path as the identifier, but that's wrong... Greetings, Andres Freund
