public inbox for [email protected]  

help / color / mirror / Atom feed

[PATCH 03/12] Make sure published XIDs are persistent
128+ messages / 3 participants
[nested] [flat]

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v9 3/9] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 441445927e..da8a460722 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 1ccc51575a..f7909aa1d7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1162,7 +1162,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 134f6862da..593a4140df 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--neYutvxvOLaeuPCA
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v9-0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/12] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 5b657ec724..8db3727502 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--45Z9DzgjV8m4Oswq
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/12] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 5b657ec724..8db3727502 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--45Z9DzgjV8m4Oswq
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v7 3/9] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 441445927e..da8a460722 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index b7f8e12aea..18dd4ff1eb 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 134f6862da..593a4140df 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--JYK4vJDZwFMowpUq
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="v7-0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH v1 2/2] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 4e6a3df6b8..85b1c21ee0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -1996,7 +2031,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 377afb8732..1a503c1447 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1159,7 +1159,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index f49a57b35e..536a5e653b 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.27.0


----Next_Part(Mon_Mar__8_17_32_42_2021_572)----





^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--XsQoSWH+UP9D9v3l
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 2/8] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e04250f4e9..e3128564e1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1161,7 +1161,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--f0KYrhQ4vYSV2aJu
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0003-Allow-alternate-compression-methods-for-wal_compress.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 04192b7add..0183589b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1171,7 +1171,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--0qVF/w3MHQqLSynd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread

* [PATCH 03/10] Make sure published XIDs are persistent
@ 2021-03-08 06:43 Kyotaro Horiguchi <[email protected]>
  0 siblings, 0 replies; 128+ messages in thread

From: Kyotaro Horiguchi @ 2021-03-08 06:43 UTC (permalink / raw)

pg_xact_status() premises that XIDs obtained by
pg_current_xact_id(_if_assigned)() are persistent beyond a crash. But
XIDs are not guaranteed to go beyond WAL buffers before commit and
thus XIDs may vanish if server crashes before commit. This patch
guarantees the XID shown by the functions to be flushed out to disk.

Copied from: https://www.postgresql.org/message-id/20210308.173242.463790587797836129.horikyota.ntt%40gmail.com
---
 src/backend/access/transam/xact.c | 55 +++++++++++++++++++++++++------
 src/backend/access/transam/xlog.c |  2 +-
 src/backend/utils/adt/xid8funcs.c | 12 ++++++-
 src/include/access/xact.h         |  3 +-
 4 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6395a9b240..38e978d238 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -201,7 +201,7 @@ typedef struct TransactionStateData
 	int			prevSecContext; /* previous SecurityRestrictionContext */
 	bool		prevXactReadOnly;	/* entry-time xact r/o state */
 	bool		startedInRecovery;	/* did we start in recovery? */
-	bool		didLogXid;		/* has xid been included in WAL record? */
+	XLogRecPtr 	minLSN;			/* LSN needed to reach to record the xid */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
 	bool		chain;			/* start a new block after this one */
 	bool		assigned;		/* assigned to top-level XID */
@@ -520,14 +520,46 @@ GetCurrentFullTransactionIdIfAny(void)
  *	MarkCurrentTransactionIdLoggedIfAny
  *
  * Remember that the current xid - if it is assigned - now has been wal logged.
+ *
+ * upto is the LSN up to which we need to flush WAL to ensure the current xid
+ * to be persistent. See EnsureCurrentTransactionIdLogged().
  */
 void
-MarkCurrentTransactionIdLoggedIfAny(void)
+MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto)
 {
-	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId))
-		CurrentTransactionState->didLogXid = true;
+	if (FullTransactionIdIsValid(CurrentTransactionState->fullTransactionId) &&
+		XLogRecPtrIsInvalid(CurrentTransactionState->minLSN))
+		CurrentTransactionState->minLSN = upto;
 }
 
+/*
+ *	EnsureCurrentTransactionIdLogged
+ *
+ * Make sure that the current top XID is WAL-logged.
+ */
+void
+EnsureTopTransactionIdLogged(void)
+{
+	/*
+	 * We need at least one WAL record for the current top transaction to be
+	 * flushed out.  Write one if we don't have one yet.
+	 */
+	if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+	{
+		xl_xact_assignment xlrec;
+
+		xlrec.xtop = XidFromFullTransactionId(XactTopFullTransactionId);
+		Assert(TransactionIdIsValid(xlrec.xtop));
+		xlrec.nsubxacts = 0;
+
+		XLogBeginInsert();
+		XLogRegisterData((char *) &xlrec, MinSizeOfXactAssignment);
+		TopTransactionStateData.minLSN =
+			XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+	}
+
+	XLogFlush(TopTransactionStateData.minLSN);
+}
 
 /*
  *	GetStableLatestTransactionId
@@ -616,14 +648,14 @@ AssignTransactionId(TransactionState s)
 	 * When wal_level=logical, guarantee that a subtransaction's xid can only
 	 * be seen in the WAL stream if its toplevel xid has been logged before.
 	 * If necessary we log an xact_assignment record with fewer than
-	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if didLogXid isn't set
+	 * PGPROC_MAX_CACHED_SUBXIDS. Note that it is fine if minLSN isn't set
 	 * for a transaction even though it appears in a WAL record, we just might
 	 * superfluously log something. That can happen when an xid is included
 	 * somewhere inside a wal record, but not in XLogRecord->xl_xid, like in
 	 * xl_standby_locks.
 	 */
 	if (isSubXact && XLogLogicalInfoActive() &&
-		!TopTransactionStateData.didLogXid)
+		XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
 		log_unknown_top = true;
 
 	/*
@@ -693,6 +725,7 @@ AssignTransactionId(TransactionState s)
 			log_unknown_top)
 		{
 			xl_xact_assignment xlrec;
+			XLogRecPtr		   endptr;
 
 			/*
 			 * xtop is always set by now because we recurse up transaction
@@ -707,11 +740,13 @@ AssignTransactionId(TransactionState s)
 			XLogRegisterData((char *) unreportedXids,
 							 nUnreportedXids * sizeof(TransactionId));
 
-			(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
+			endptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT);
 
 			nUnreportedXids = 0;
-			/* mark top, not current xact as having been logged */
-			TopTransactionStateData.didLogXid = true;
+
+			/* set minLSN of top, not of current xact if not yet */
+			if (XLogRecPtrIsInvalid(TopTransactionStateData.minLSN))
+				TopTransactionStateData.minLSN = endptr;
 		}
 	}
 }
@@ -2022,7 +2057,7 @@ StartTransaction(void)
 	 * initialize reported xid accounting
 	 */
 	nUnreportedXids = 0;
-	s->didLogXid = false;
+	s->minLSN = InvalidXLogRecPtr;
 
 	/*
 	 * must initialize resource-management stuff first
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 15da91a8dd..6eb46ea8a7 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1172,7 +1172,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	 */
 	WALInsertLockRelease();
 
-	MarkCurrentTransactionIdLoggedIfAny();
+	MarkCurrentTransactionIdLoggedIfAny(EndPos);
 
 	END_CRIT_SECTION();
 
diff --git a/src/backend/utils/adt/xid8funcs.c b/src/backend/utils/adt/xid8funcs.c
index cc2b4ac797..992482f8c8 100644
--- a/src/backend/utils/adt/xid8funcs.c
+++ b/src/backend/utils/adt/xid8funcs.c
@@ -357,6 +357,8 @@ bad_format:
 Datum
 pg_current_xact_id(PG_FUNCTION_ARGS)
 {
+	FullTransactionId xid;
+
 	/*
 	 * Must prevent during recovery because if an xid is not assigned we try
 	 * to assign one, which would fail. Programs already rely on this function
@@ -365,7 +367,12 @@ pg_current_xact_id(PG_FUNCTION_ARGS)
 	 */
 	PreventCommandDuringRecovery("pg_current_xact_id()");
 
-	PG_RETURN_FULLTRANSACTIONID(GetTopFullTransactionId());
+	xid = GetTopFullTransactionId();
+
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
+	PG_RETURN_FULLTRANSACTIONID(xid);
 }
 
 /*
@@ -380,6 +387,9 @@ pg_current_xact_id_if_assigned(PG_FUNCTION_ARGS)
 	if (!FullTransactionIdIsValid(topfxid))
 		PG_RETURN_NULL();
 
+	/* the XID is going to be published, make sure it is psersistent */
+	EnsureTopTransactionIdLogged();
+
 	PG_RETURN_FULLTRANSACTIONID(topfxid);
 }
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 34cfaf542c..a61e4d6da5 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -386,7 +386,8 @@ extern FullTransactionId GetTopFullTransactionId(void);
 extern FullTransactionId GetTopFullTransactionIdIfAny(void);
 extern FullTransactionId GetCurrentFullTransactionId(void);
 extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
-extern void MarkCurrentTransactionIdLoggedIfAny(void);
+extern void MarkCurrentTransactionIdLoggedIfAny(XLogRecPtr upto);
+extern void EnsureTopTransactionIdLogged(void);
 extern bool SubTransactionIsActive(SubTransactionId subxid);
 extern CommandId GetCurrentCommandId(bool used);
 extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
-- 
2.17.0


--jozmn01XJZjDjM3N
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
 filename="0004-wal_compression_method-default-to-zlib.patch"



^ permalink  raw  reply  [nested|flat] 128+ messages in thread