At promotion, archive last segment from old timeline with .partial suffix.

Previously, we would archive the possible-incomplete WAL segment with its
normal filename, but that causes trouble if the server owning that timeline
is still running, and tries to archive the same segment later. It's not nice
for the standby to trip up the master's archival like that. And it's pretty
confusing, anyway, to have an incomplete segment in the archive that's
indistinguishable from a normal, complete segment.

To avoid such confusion, add a .partial suffix to the file. Or to be more
precise, make a copy of the old segment under the .partial suffix, and
archive that instead of the original file. pg_receivexlog also uses the
.partial suffix for the same purpose, to tell apart incompletely streamed
files from complete ones.

There is no automatic mechanism to use the .partial files at recovery, so
they will go unused, unless the administrator manually copies to them to
the pg_xlog directory (and removes the .partial suffix). Recovery won't
normally need the WAL - when recovering to the new timeline, it will find
the same WAL on the first segment on the new timeline instead - but it
nevertheless feels better to archive the file with the .partial suffix, for
debugging purposes if nothing else.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/include/postmaster/pgarch.h b/src/include/postmaster/pgarch.h
index 9f692eb47f..425e2ab4f0 100644
--- a/src/include/postmaster/pgarch.h
+++ b/src/include/postmaster/pgarch.h
@@ -24,7 +24,7 @@
  */
 #define MIN_XFN_CHARS	16
 #define MAX_XFN_CHARS	40
-#define VALID_XFN_CHARS "0123456789ABCDEF.history.backup"
+#define VALID_XFN_CHARS "0123456789ABCDEF.history.backup.partial"
 
 /* ----------
  * Functions called from postmaster