public inbox for [email protected]  

help / color / mirror / Atom feed

From: Adam Lee <[email protected]>
Subject: [PATCH] Fix minRecoveryPoint not advanced past checkpoint in CreateRestartPoint
Date: Tue, 31 Mar 2026 18:43:53 +0800

When recovery_target_action=shutdown triggers, the checkpointer performs
a shutdown restartpoint via CreateRestartPoint. If a new CHECKPOINT
record was replayed shortly before the recovery target, the restartpoint
advances minRecoveryPoint to the end of that CHECKPOINT record. And the
following replay doesn't advance minRecoveryPoint, it's assumed that
flushing the buffers will do that as a side-effect.

But no-op records replayed after the CHECKPOINT (such as RESTORE_POINT) do
not dirty any pages, so the minRecoveryPoint is not updated as expected.
As a result, minRecoveryPoint in pg_control ends up behind the actual
replay position. This does not cause a recovery correctness issue,
however the inaccurate pg_controldata "Minimum recovery ending location"
prevents users or tools from using this value to verify that recovery
has reached a specific restore point.

Fix by reading the current replay position from shared memory after
advancing minRecoveryPoint to the checkpoint, and advancing it further
if replay has progressed past the checkpoint.

Reproducer:
  CHECKPOINT; SELECT pg_create_restore_point('test_rp');
  -- recover with recovery_target_name + recovery_target_action=shutdown
  -- pg_controldata shows minRecoveryPoint 104 bytes behind
---
 src/backend/access/transam/xlog.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 2c1c6f88b74..ec639054620 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7868,11 +7868,34 @@ CreateRestartPoint(int flags)
 			{
 				ControlFile->minRecoveryPoint = lastCheckPointEndPtr;
 				ControlFile->minRecoveryPointTLI = lastCheckPoint.ThisTimeLineID;
+			}
+
+			/*
+			 * Also advance minRecoveryPoint past any WAL replayed after
+			 * the checkpoint.  Normally this happens as a side effect of
+			 * flushing dirty buffers, but during a shutdown restartpoint
+			 * there may be records between the checkpoint and the
+			 * recovery target that didn't dirty any buffers (e.g. a
+			 * RESTORE_POINT record).  Without this, a shutdown triggered
+			 * by recovery_target_action leaves minRecoveryPoint behind
+			 * the actual replay position.
+			 */
+			{
+				XLogRecPtr	replayPtr;
+				TimeLineID	replayTLI;
 
-				/* update local copy */
-				LocalMinRecoveryPoint = ControlFile->minRecoveryPoint;
-				LocalMinRecoveryPointTLI = ControlFile->minRecoveryPointTLI;
+				replayPtr = GetCurrentReplayRecPtr(&replayTLI);
+				if (ControlFile->minRecoveryPoint < replayPtr)
+				{
+					ControlFile->minRecoveryPoint = replayPtr;
+					ControlFile->minRecoveryPointTLI = replayTLI;
+				}
 			}
+
+			/* update local copy */
+			LocalMinRecoveryPoint = ControlFile->minRecoveryPoint;
+			LocalMinRecoveryPointTLI = ControlFile->minRecoveryPointTLI;
+
 			if (flags & CHECKPOINT_IS_SHUTDOWN)
 				ControlFile->state = DB_SHUTDOWNED_IN_RECOVERY;
 		}
-- 
2.47.3


--IxHwtWaH/DA3wSaA--

view thread (489+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected]
  Subject: Re: [PATCH] Fix minRecoveryPoint not advanced past checkpoint in CreateRestartPoint
  In-Reply-To: <no-message-id-1473238@localhost>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox