From d45d0c95a0ddee51563b5e94ea046ce4c5cf1baf Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Thu, 26 Dec 2024 14:06:01 +0900 Subject: [PATCH v1 1/2] Fix failure with incorrect epoch for future 2PC files at recovery A two-phase file in the future would be able to trigger an assertion failure in AdjustToFullTransactionId() as the epoch counter would underflow if the checkpoint record uses an epoch of 0. In non-assert builds, this would create a WARNING message referring to a 2PC file with an epoch of "FFFFFFFF" (or UINT32_MAX), as an effect of the underflow calculation. Issue introduced by 5a1dfde8334b. Reported-by: Vitaly Davydov Discussion: https://postgr.es/m/13b5b6-676c3080-4d-531db900@47931709 Backpatch-through: 17 --- src/backend/access/transam/twophase.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c index 49be1df91c..d2649264f9 100644 --- a/src/backend/access/transam/twophase.c +++ b/src/backend/access/transam/twophase.c @@ -947,10 +947,9 @@ AdjustToFullTransactionId(TransactionId xid) nextXid = XidFromFullTransactionId(nextFullXid); epoch = EpochFromFullTransactionId(nextFullXid); - if (unlikely(xid > nextXid)) + if (unlikely(xid > nextXid) && epoch > 0) { /* Wraparound occurred, must be from a prev epoch. */ - Assert(epoch > 0); epoch--; } -- 2.45.2