Re: [HACKERS] [PATCH] Rename pg_switch_xlog to pg_switch_wal

On Fri, Feb  3, 2017 at 05:21:28AM -0500, Stephen Frost wrote:
> > Also googling for pg_wal, I'm finding food for thought like this
> > IBM technote:
> > http://www-01.ibm.com/support/docview.wss?uid=isg3T1015637
> > which recommends to 
> > "Remove all files under /var/lib/pgsql/9.0/data/pg_wal/"
> > and also calls that directory the "write-ahead log directory"
> > which is quite confusing because apparently it's the destination of
> > their archive command.
> 
> It's certainly unfortunate that people have thought that they can create
> arbitrary directories under the PG data directory.  That's never going
> to be safe, witness that we've created new directories under PGDATA in
> the last few releases and I don't see any reason why that would change
> moving forward.  Perhaps we should check for the existance of such a
> directory during pg_upgrade and throw an error, and we should go back
> and do the same for other directories which have been added over
> releases, but I'm not sure I can see an argument for doing much more
> than that.

Actually, pg_upgrade already checks for some odd directories stored
inside of PGDATA:
WARNING:  new data directory should not be inside theold data directory, e.g. %s\n", old_cluster_pgdata);
WARNING:  user-defined tablespace locations shouldnot be inside the data directory, e.g. %s\n", old_tablespace_dir);

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
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