At promotion, don't leave behind a partial segment on the old timeline.

With commit de768844, a copy of the partial segment was archived with the
.partial suffix, but the original file was still left in pg_xlog, so it
didn't actually solve the problems with archiving the partial segment that
it was supposed to solve. With this patch, the partial segment is renamed
rather than copied, so we only archive it with the .partial suffix.

Also be more robust in detecting if the last segment is already being
archived. Previously I used XLogArchiveIsBusy() for that, but that's not
quite right. With archive_mode='always', there might be a .ready file for
it, and we don't want to rename it to .partial in that case.

The old segment is needed until we're fully committed to the new timeline,
i.e. until we've written the end-of-recovery WAL record and updated the
min recovery point and timeline in the control file. So move the renaming
later in the startup sequence, after all that's been done.

1 files changed, 35 insertions, 0 deletions

diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 4c69b738bc1..7af56a9a740 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -698,6 +698,41 @@ XLogArchiveIsBusy(const char *xlog)
 }
 
 /*
+ * XLogArchiveIsReadyOrDone
+ *
+ * Check to see if an XLOG segment file has a .ready or .done file.
+ * This is similar to XLogArchiveIsBusy(), but returns true if the file
+ * is already archived or is about to be archived.
+ *
+ * This is currently only used at recovery.  During normal operation this
+ * would be racy: the file might get removed or marked with .ready as we're
+ * checking it, or immediately after we return.
+ */
+bool
+XLogArchiveIsReadyOrDone(const char *xlog)
+{
+	char		archiveStatusPath[MAXPGPATH];
+	struct stat stat_buf;
+
+	/* First check for .done --- this means archiver is done with it */
+	StatusFilePath(archiveStatusPath, xlog, ".done");
+	if (stat(archiveStatusPath, &stat_buf) == 0)
+		return true;
+
+	/* check for .ready --- this means archiver is still busy with it */
+	StatusFilePath(archiveStatusPath, xlog, ".ready");
+	if (stat(archiveStatusPath, &stat_buf) == 0)
+		return true;
+
+	/* Race condition --- maybe archiver just finished, so recheck */
+	StatusFilePath(archiveStatusPath, xlog, ".done");
+	if (stat(archiveStatusPath, &stat_buf) == 0)
+		return true;
+
+	return false;
+}
+
+/*
  * XLogArchiveIsReady
  *
  * Check to see if an XLOG segment file has an archive notification (.ready)