On Tue, Sep 5, 2017 at 7:54 PM, Vladimir Borodin <root@simply.name> wrote: > 5 сент. 2017 г., в 12:31, Chris Travers <chris.travers@adjust.com> > написал(а): > > I think the simplest solution for now is to skip any files ending in .conf, > .log, and serverlog.
This is not a portable solution. Users can include configuration files with the names they want. So the current patch as proposed is definitely not something worth it.
Actually that is exactly why I think the long-term solution is to figure out what we need to copy and not copy anything we don't recognise.
That means the following directories as far as I can see:
* base
* global
* pg_xlog/pg_wal
* pg_clog/pg_xact
* pg_commit_ts
* pg_twophase
* pg_snapshots?
Are there any other directories I am missing?
At any rate, I think the current state makes it very difficult to test rewind adequately, and it makes it extremely difficult to use in a non-trivial environment because you have to handle replication slots, configuration files, and so forth yourself, and you have to be aware that these *may* or *may not* be consistently clobbered by a rewind, so you have to have some way of applying another set of files in following a rewind.
If nothing else we ought to *at least* special case the recovery.conf and the postgresql.auto.conf, and pg_replslot because these are always located there and should never be clobbered.
> For example, in archive_command we put WALs for archiving from > pg_xlog/pg_wal into another directory inside PGDATA and than another cron > task makes real archiving. This directory ideally should be skipped by > pg_rewind, but it would not be handled by proposed change.
I would be curious to follow the reasoning for such a two-phase archiving (You basically want to push it in two places, no? But why not just use pg_receivexlog then?). This is complicated to handle from the point of view of availability and backup reliability + durability. > While it is definitely an awful idea the user can easily put something > strange (i.e. logs) to any important directory in PGDATA (i.e. into base or > pg_wal). Or how for example pg_replslot should be handled (I asked about it > a couple of years ago [1])? It seems that a glob/regexp for things to skip > is a more universal solution. > > [1] > https://www.postgresql.org/message-id/flat/8DDCCC9D-450D-4CA2-8CF6-40B382F1F699%40simply.name
Well, keeping the code simple is not always a bad thing. Logs are an example that can be easily countered, as well as archives in your case.
