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commit    78ea8b5daab9237fd42d7a8a836c1c451765499f
Author:   Michael Paquier <michael@paquier.xyz>
Date:     Fri Sep 28 02:54:38 2018 +0000

    Fix WAL recycling on standbys depending on archive_mode
    
    A restart point or a checkpoint recycling WAL segments treats segments
    marked with neither ".done" (archiving is done) or ".ready" (segment is
    ready to be archived) in archive_status the same way for archive_mode
    being "on" or "always".  While for a primary this is fine, a standby
    running a restart point with archive_mode = on would try to mark such a
    segment as ready for archiving, which is something that will never
    happen except after the standby is promoted.
    
    Note that this problem applies only to WAL segments coming from the
    local pg_wal the first time archive recovery is run.  Segments part of a
    self-contained base backup are the most common case where this could
    happen, however even in this case normally the .done markers would be
    most likely part of the backup.  Segments recovered from an archive are
    marked as .ready or .done by the startup process, and segments finished
    streaming are marked as such by the WAL receiver, so they are handled
    already.
    
    Reported-by: Haruka Takatsuka
    Author: Michael Paquier
    Discussion: https://postgr.es/m/15402-a453c90ed4cf88b2@postgresql.org
    Backpatch-through: 9.5, where archive_mode = always has been added.


 src/backend/access/transam/xlogarchive.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 4a039b11901..d40317168e2 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -620,9 +620,16 @@ XLogArchiveCheckDone(const char *xlog)
 {
 	char		archiveStatusPath[MAXPGPATH];
 	struct stat stat_buf;
+	bool		inRecovery = RecoveryInProgress();
 
-	/* Always deletable if archiving is off */
-	if (!XLogArchivingActive())
+	/*
+	 * The file is always deletable if archive_mode is "off".  On standbys
+	 * archiving is disabled if archive_mode is "on", and enabled with
+	 * "always".  On a primary, archiving is enabled if archive_mode is "on"
+	 * or "always".
+	 */
+	if (!((XLogArchivingActive() && !inRecovery) ||
+		  (XLogArchivingAlways() && inRecovery)))
 		return true;
 
 	/* First check for .done --- this means archiver is done with it */


[parent: aaf10f32a308]