postgres.git / summary / log / commit / refs

commit    6daeeb1f9196e5d59aa7d5c9ef7ed67b3f3ac4b5
Author:   Peter Geoghegan <pg@bowt.ie>
Date:     Mon Jan 02 18:16:51 2023 +0000
First released in: 16.0

    Avoid special XID snapshotConflictHorizon values.
    
    Don't allow VACUUM to WAL-log the value FrozenTransactionId as the
    snapshotConflictHorizon of freezing or visibility map related WAL
    records.
    
    The only special XID value that's an allowable snapshotConflictHorizon
    is InvalidTransactionId, which is interpreted as "record definitely
    doesn't require a recovery conflict".
    
    Author: Peter Geoghegan <pg@bowt.ie>
    Discussion: https://postgr.es/m/CAH2-WznuNGSzF8v6OsgjaC5aYsb3cZ6HW6MLm30X0d65cmSH6A@mail.gmail.com


 src/backend/access/heap/vacuumlazy.c | 8 +++++---
 src/backend/storage/ipc/standby.c    | 1 +
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 9923994b50e..5d8fd2fb727 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -1698,7 +1698,8 @@ retry:
 					}
 
 					/* Track newest xmin on page. */
-					if (TransactionIdFollows(xmin, prunestate->visibility_cutoff_xid))
+					if (TransactionIdFollows(xmin, prunestate->visibility_cutoff_xid) &&
+						TransactionIdIsNormal(xmin))
 						prunestate->visibility_cutoff_xid = xmin;
 				}
 				break;
@@ -1863,7 +1864,7 @@ retry:
 		 * because visibility_cutoff_xid will be logged by our caller in a
 		 * moment.
 		 */
-		Assert(cutoff == FrozenTransactionId ||
+		Assert(!TransactionIdIsValid(cutoff) ||
 			   cutoff == prunestate->visibility_cutoff_xid);
 	}
 #endif
@@ -3293,7 +3294,8 @@ heap_page_is_all_visible(LVRelState *vacrel, Buffer buf,
 					}
 
 					/* Track newest xmin on page. */
-					if (TransactionIdFollows(xmin, *visibility_cutoff_xid))
+					if (TransactionIdFollows(xmin, *visibility_cutoff_xid) &&
+						TransactionIdIsNormal(xmin))
 						*visibility_cutoff_xid = xmin;
 
 					/* Check whether this tuple is already frozen or not */
diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c
index f43229dfda6..ede00fee935 100644
--- a/src/backend/storage/ipc/standby.c
+++ b/src/backend/storage/ipc/standby.c
@@ -493,6 +493,7 @@ ResolveRecoveryConflictWithSnapshot(TransactionId snapshotConflictHorizon,
 	if (!TransactionIdIsValid(snapshotConflictHorizon))
 		return;
 
+	Assert(TransactionIdIsNormal(snapshotConflictHorizon));
 	backends = GetConflictingVirtualXIDs(snapshotConflictHorizon,
 										 locator.dbOid);
 	ResolveRecoveryConflictWithVirtualXIDs(backends,


[parent: 1fd3dd204899]