From 10425b3c062ed3972c0ad067adb7c14c5dca43c8 Mon Sep 17 00:00:00 2001 From: Kyotaro Horiguchi Date: Thu, 18 Jun 2020 14:49:48 +0900 Subject: [PATCH v2 2/2] Forcibly initialize lastRemovedSegNo at the first checkpoint If we have a replication slot retaining all existing WAL segments, a checkpoint doesn't initialize lastRemovedSegNo. That means pg_replication_slots can not show min_safe_lsn until any slot loses a segment. Forcibly initialize it even if no WAL segments are removed at the first checkpoint. --- src/backend/access/transam/xlog.c | 33 +++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 940f5fcb18..282bac32ab 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -4025,6 +4025,16 @@ RemoveOldXlogFiles(XLogSegNo segno, XLogRecPtr lastredoptr, XLogRecPtr endptr) DIR *xldir; struct dirent *xlde; char lastoff[MAXFNAMELEN]; + char oldest[MAXFNAMELEN]; + bool remember_oldest = false; + + /* + * If we haven't set the initial last removed segno, force to set it even + * if we wouldn't have removed any segments. + */ + oldest[0] = 0; + if (XLogGetLastRemovedSegno() == 0) + remember_oldest = true; /* * Construct a filename of the last segment to be kept. The timeline ID @@ -4062,10 +4072,33 @@ RemoveOldXlogFiles(XLogSegNo segno, XLogRecPtr lastredoptr, XLogRecPtr endptr) { /* Update the last removed location in shared memory first */ UpdateLastRemovedPtr(xlde->d_name); + remember_oldest = false; RemoveXlogFile(xlde->d_name, lastredoptr, endptr); } } + /* Remember the oldest file left in the directotry */ + else if(remember_oldest && + (oldest[0] == 0 || strcmp(xlde->d_name + 8, oldest + 8) < 0)) + strncpy(oldest, xlde->d_name, MAXFNAMELEN); + } + + /* + * We haven't initialize the pointer, initialize it. + * The last removed pointer is the oldest existing segment minus 1. + */ + if (remember_oldest && oldest[0] != 0) + { + uint32 tli; + XLogSegNo segno; + + XLogFromFileName(oldest, &tli, &segno, wal_segment_size); + + if (segno > 1) + { + XLogFileName(oldest, tli, segno - 1, wal_segment_size); + UpdateLastRemovedPtr(oldest); + } } FreeDir(xldir); -- 2.18.4