postgres.git / summary / log / commit / refs

commit    d3c9ccdf1edec4f486a860e279d2ef2e22f5e4f1
Author:   Fujii Masao <fujii@postgresql.org>
Date:     Wed Sep 02 05:35:10 2026 +0000

    Fix checkpointer restartpoint assertion failure
    
    When recovery starts from a backup without a signal file, pg_subtrans
    is not started at the beginning of recovery and remains unstarted
    throughout recovery. However, previously, a restartpoint run by
    the checkpointer during recovery nevertheless tried to truncate
    pg_subtrans, triggering the assertion failure:
    
        TRAP: failed Assert("TransactionIdIsValid(initial)")
    
    This commit fixes this by tracking whether pg_subtrans has been
    started during recovery, and have the checkpointer check this flag
    before truncating pg_subtrans at restartpoints.
    
    Backpatch to all supported versions.
    
    Reported-by: Imran Zaheer <imran.zhir@gmail.com>
    Author: Imran Zaheer <imran.zhir@gmail.com>
    Author: Fujii Masao <masao.fujii@gmail.com>
    Reviewed-by: Michael Paquier <michael@paquier.xyz>
    Discussion: https://postgr.es/m/CA+UBfamzfEReT0VOGRUW_=_AecCYQ-CNKLR_T4Q+YEmJAH3fdg@mail.gmail.com
    Backpatch-through: 14


 src/backend/access/transam/xlog.c | 42 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index ec84c77ddfa..bb84525e665 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -689,6 +689,12 @@ typedef struct XLogCtlData
 	 */
 	bool		SharedPromoteIsTriggered;
 
+	/*
+	 * SharedRecoverySubtransInitialized indicates whether hot standby
+	 * initialization has started pg_subtrans. Protected by info_lck.
+	 */
+	bool		SharedRecoverySubtransInitialized;
+
 	/*
 	 * WalWriterSleeping indicates whether the WAL writer is currently in
 	 * low-power mode (and hence should be nudged if an async commit occurs).
@@ -971,6 +977,8 @@ static void ReadControlFile(void);
 static char *str_time(pg_time_t tnow);
 static void SetPromoteIsTriggered(void);
 static bool CheckForStandbyTrigger(void);
+static bool RecoverySubtransInitialized(void);
+static void SetRecoverySubtransInitialized(void);
 
 #ifdef WAL_DEBUG
 static void xlog_outrec(StringInfo buf, XLogReaderState *record);
@@ -5295,6 +5303,7 @@ XLOGShmemInit(void)
 	XLogCtl->SharedHotStandbyActive = false;
 	XLogCtl->InstallXLogFileSegmentActive = false;
 	XLogCtl->SharedPromoteIsTriggered = false;
+	XLogCtl->SharedRecoverySubtransInitialized = false;
 	XLogCtl->WalWriterSleeping = false;
 
 	SpinLockInit(&XLogCtl->Insert.insertpos_lck);
@@ -7308,6 +7317,7 @@ StartupXLOG(void)
 			 * during recovery and need not be started yet.
 			 */
 			StartupSUBTRANS(oldestActiveXID);
+			SetRecoverySubtransInitialized();
 
 			/*
 			 * If we're beginning at a shutdown checkpoint, we know that
@@ -10029,10 +10039,10 @@ CreateRestartPoint(int flags)
 	 * Truncate pg_subtrans if possible.  We can throw away all data before
 	 * the oldest XMIN of any running transaction.  No future transaction will
 	 * attempt to reference any pg_subtrans entry older than that (see Asserts
-	 * in subtrans.c).  When hot standby is disabled, though, we mustn't do
-	 * this because StartupSUBTRANS hasn't been called yet.
+	 * in subtrans.c).  During recovery, don't truncate pg_subtrans until hot
+	 * standby initialization has started it.
 	 */
-	if (EnableHotStandby)
+	if (RecoverySubtransInitialized())
 		TruncateSUBTRANS(GetOldestTransactionIdConsideredRunning());
 
 	/* Real work is done; log and update stats. */
@@ -13408,6 +13418,32 @@ CheckPromoteSignal(void)
 	return false;
 }
 
+/*
+ * Has hot standby initialization started pg_subtrans?
+ */
+static bool
+RecoverySubtransInitialized(void)
+{
+	bool		result;
+
+	SpinLockAcquire(&XLogCtl->info_lck);
+	result = XLogCtl->SharedRecoverySubtransInitialized;
+	SpinLockRelease(&XLogCtl->info_lck);
+
+	return result;
+}
+
+/*
+ * Remember that hot standby initialization has started pg_subtrans.
+ */
+static void
+SetRecoverySubtransInitialized(void)
+{
+	SpinLockAcquire(&XLogCtl->info_lck);
+	XLogCtl->SharedRecoverySubtransInitialized = true;
+	SpinLockRelease(&XLogCtl->info_lck);
+}
+
 /*
  * Wake up startup process to replay newly arrived WAL, or to notice that
  * failover has been requested.


[parent: 03851df1105d]