pg_rewind just doesn't fsync *anything*?

Hi,

how come that the only comment in pg_rewind about fsyncing is '
void
close_target_file(void)
{
...
/* fsync? */
}

Isn't that a bit, uh, minimal for a utility that's likely to be used in
failover scenarios?

I think we might actually be "saved" due to
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=2ce439f33
because pg_rewind appears to leave the cluster in

ControlFile_new.state = DB_IN_ARCHIVE_RECOVERY;
updateControlFile(&ControlFile_new);

a state that StartupXLOG will treat as needing recovery:

if (ControlFile->state != DB_SHUTDOWNED &&
ControlFile->state != DB_SHUTDOWNED_IN_RECOVERY)
SyncDataDirectory();

but that code went in after pg_rewind, so this certainly can't be an
intentional save.

I also don't think it's ok that you need to start the cluster to make it
safe against a crash?

I guess the easiest fix would be to shell out to initdb -s?

Greetings,

Andres Freund