Prevent WAL files created by pg_basebackup -x/X from being archived again.

WAL (and timeline history) files created by pg_basebackup did not
maintain the new base backup's archive status. That's currently not a
problem if the new node is used as a standby - but if that node is
promoted all still existing files can get archived again.  With a high
wal_keep_segment settings that can happen a significant time later -
which is quite confusing.

Change both the backend (for the -x/-X fetch case) and pg_basebackup
(for -X stream) itself to always mark WAL/timeline files included in
the base backup as .done. That's in line with walreceiver.c doing so.

The verbosity of the pg_basebackup changes show pretty clearly that it
needs some refactoring, but that'd result in not be backpatchable
changes.

Backpatch to 9.1 where pg_basebackup was introduced.

Discussion: 20141205002854.GE21964@awork2.anarazel.de

1 files changed, 24 insertions, 0 deletions

diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index c52e453d2fc..fcc7cf271b9 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -404,6 +404,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 					errmsg("unexpected WAL file size \"%s\"", walFiles[i])));
 			}
 
+			/* send the WAL file itself */
 			_tarWriteHeader(pathbuf, NULL, &statbuf);
 
 			while ((cnt = fread(buf, 1, Min(sizeof(buf), XLogSegSize - len), fp)) > 0)
@@ -428,7 +429,17 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 			}
 
 			/* XLogSegSize is a multiple of 512, so no need for padding */
+
 			FreeFile(fp);
+
+			/*
+			 * Mark file as archived, otherwise files can get archived again
+			 * after promotion of a new node. This is in line with
+			 * walreceiver.c always doing a XLogArchiveForceDone() after a
+			 * complete segment.
+			 */
+			StatusFilePath(pathbuf, walFiles[i], ".done");
+			sendFileWithContent(pathbuf, "");
 		}
 
 		/*
@@ -452,6 +463,10 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
 						 errmsg("could not stat file \"%s\": %m", pathbuf)));
 
 			sendFile(pathbuf, pathbuf, &statbuf, false);
+
+			/* unconditionally mark file as archived */
+			StatusFilePath(pathbuf, fname, ".done");
+			sendFileWithContent(pathbuf, "");
 		}
 
 		/* Send CopyDone message for the last tar file */
@@ -900,6 +915,15 @@ sendDir(char *path, int basepathlen, bool sizeonly, List *tablespaces)
 				_tarWriteHeader(pathbuf + basepathlen + 1, NULL, &statbuf);
 			}
 			size += 512;		/* Size of the header just added */
+
+			/*
+			 * Also send archive_status directory (by hackishly reusing
+			 * statbuf from above ...).
+			 */
+			if (!sizeonly)
+				_tarWriteHeader("./pg_xlog/archive_status", NULL, &statbuf);
+			size += 512;		/* Size of the header just added */
+
 			continue;			/* don't recurse into pg_xlog */
 		}