Revert recent changes related to handling of 2PC files at recovery

michaelpq · michaelpq · commit 4d6d7bdc0642 · 2025-01-17T13:27:48.000+09:00
This commit reverts 8f67f99 (down to v13) and c3de0f9 (down to v17), as these are proving to not be completely correct regarding two aspects: - In v17 and newer branches, c3de0f9's check for epoch handling is incorrect, and does not correctly handle frozen epochs. A logic closer to widen_snapshot_xid() should be used. The 2PC code should try to integrate deeper with FullTransactionIds, 5a1dfde being not enough. - In v13 and newer branches, 8f67f99 is a workaround for the real issue, which is that we should not attempt CLOG lookups without reaching consistency. This exists since 728bd99, and this is reachable with ProcessTwoPhaseBuffer() called by restoreTwoPhaseData() at the beginning of recovery. Per discussion with Noah Misch. Discussion: https://postgr.es/m/20250116010051.f3.nmisch@google.com Backpatch-through: 13
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
@@ -2167,40 +2167,40 @@ ProcessTwoPhaseBuffer(TransactionId xid,
 	if (!fromdisk)
 		Assert(prepare_start_lsn != InvalidXLogRecPtr);
 
-	/* Reject XID if too new */
-	if (TransactionIdFollowsOrEquals(xid, origNextXid))
+	/* Already processed? */
+	if (TransactionIdDidCommit(xid) || TransactionIdDidAbort(xid))
 	{
 		if (fromdisk)
 		{
 			ereport(WARNING,
-					(errmsg("removing future two-phase state file for transaction %u",
+					(errmsg("removing stale two-phase state file for transaction %u",
 							xid)));
 			RemoveTwoPhaseFile(xid, true);
 		}
 		else
 		{
 			ereport(WARNING,
-					(errmsg("removing future two-phase state from memory for transaction %u",
+					(errmsg("removing stale two-phase state from memory for transaction %u",
 							xid)));
 			PrepareRedoRemove(xid, true);
 		}
 		return NULL;
 	}
 
-	/* Already processed? */
-	if (TransactionIdDidCommit(xid) || TransactionIdDidAbort(xid))
+	/* Reject XID if too new */
+	if (TransactionIdFollowsOrEquals(xid, origNextXid))
 	{
 		if (fromdisk)
 		{
 			ereport(WARNING,
-					(errmsg("removing stale two-phase state file for transaction %u",
+					(errmsg("removing future two-phase state file for transaction %u",
 							xid)));
 			RemoveTwoPhaseFile(xid, true);
 		}
 		else
 		{
 			ereport(WARNING,
-					(errmsg("removing stale two-phase state from memory for transaction %u",
+					(errmsg("removing future two-phase state from memory for transaction %u",
 							xid)));
 			PrepareRedoRemove(xid, true);
 		}

Original file line number	Diff line number	Diff line change
`@@ -2167,40 +2167,40 @@ ProcessTwoPhaseBuffer(TransactionId xid,`
`2167`	`2167`	`if (!fromdisk)`
`2168`	`2168`	`Assert(prepare_start_lsn != InvalidXLogRecPtr);`
`2169`	`2169`
`2170`		`- /* Reject XID if too new */`
`2171`		`- if (TransactionIdFollowsOrEquals(xid, origNextXid))`
	`2170`	`+ /* Already processed? */`
	`2171`	`+ if (TransactionIdDidCommit(xid) \|\| TransactionIdDidAbort(xid))`
`2172`	`2172`	`{`
`2173`	`2173`	`if (fromdisk)`
`2174`	`2174`	`{`
`2175`	`2175`	`ereport(WARNING,`
`2176`		`- (errmsg("removing future two-phase state file for transaction %u",`
	`2176`	`+ (errmsg("removing stale two-phase state file for transaction %u",`
`2177`	`2177`	`xid)));`
`2178`	`2178`	`RemoveTwoPhaseFile(xid, true);`
`2179`	`2179`	`}`
`2180`	`2180`	`else`
`2181`	`2181`	`{`
`2182`	`2182`	`ereport(WARNING,`
`2183`		`- (errmsg("removing future two-phase state from memory for transaction %u",`
	`2183`	`+ (errmsg("removing stale two-phase state from memory for transaction %u",`
`2184`	`2184`	`xid)));`
`2185`	`2185`	`PrepareRedoRemove(xid, true);`
`2186`	`2186`	`}`
`2187`	`2187`	`return NULL;`
`2188`	`2188`	`}`
`2189`	`2189`
`2190`		`- /* Already processed? */`
`2191`		`- if (TransactionIdDidCommit(xid) \|\| TransactionIdDidAbort(xid))`
	`2190`	`+ /* Reject XID if too new */`
	`2191`	`+ if (TransactionIdFollowsOrEquals(xid, origNextXid))`
`2192`	`2192`	`{`
`2193`	`2193`	`if (fromdisk)`
`2194`	`2194`	`{`
`2195`	`2195`	`ereport(WARNING,`
`2196`		`- (errmsg("removing stale two-phase state file for transaction %u",`
	`2196`	`+ (errmsg("removing future two-phase state file for transaction %u",`
`2197`	`2197`	`xid)));`
`2198`	`2198`	`RemoveTwoPhaseFile(xid, true);`
`2199`	`2199`	`}`
`2200`	`2200`	`else`
`2201`	`2201`	`{`
`2202`	`2202`	`ereport(WARNING,`
`2203`		`- (errmsg("removing stale two-phase state from memory for transaction %u",`
	`2203`	`+ (errmsg("removing future two-phase state from memory for transaction %u",`
`2204`	`2204`	`xid)));`
`2205`	`2205`	`PrepareRedoRemove(xid, true);`
`2206`	`2206`	`}`