Remove COMMIT_TS_SETTS record.

Commit 438fc4a3 prevented the WAL replay from writing
COMMIT_TS_SETTS record. By this change there is no code that
generates COMMIT_TS_SETTS record in PostgreSQL core.
Also we can think that there are no extensions using the record
because we've not received so far any complaints about the issue
that commit 438fc4a3 fixed. Therefore this commit removes
COMMIT_TS_SETTS record and its related code. Even without
this record, the timestamp required for commit timestamp feature
can be acquired from the COMMIT record.

Bump WAL page magic.
Reported-by: lx zou <zoulx1982@163.com>
Author: Fujii Masao
Reviewed-by: Alvaro Herrera
Discussion: https://postgr.es/m/16931-620d0f2fdc6108f1@postgresql.org

src/backend/access/rmgrdesc/committsdesc.c

@@ -38,31 +38,6 @@ commit_ts_desc(StringInfo buf, XLogReaderState *record)
 		appendStringInfo(buf, "pageno %d, oldestXid %u",
 						 trunc->pageno, trunc->oldestXid);
 	}
-	else if (info == COMMIT_TS_SETTS)
-	{
-		xl_commit_ts_set *xlrec = (xl_commit_ts_set *) rec;
-		int			nsubxids;
-
-		appendStringInfo(buf, "set %s/%d for: %u",
-						 timestamptz_to_str(xlrec->timestamp),
-						 xlrec->nodeid,
-						 xlrec->mainxid);
-		nsubxids = ((XLogRecGetDataLen(record) - SizeOfCommitTsSet) /
-					sizeof(TransactionId));
-		if (nsubxids > 0)
-		{
-			int			i;
-			TransactionId *subxids;
-
-			subxids = palloc(sizeof(TransactionId) * nsubxids);
-			memcpy(subxids,
-				   XLogRecGetData(record) + SizeOfCommitTsSet,
-				   sizeof(TransactionId) * nsubxids);
-			for (i = 0; i < nsubxids; i++)
-				appendStringInfo(buf, ", %u", subxids[i]);
-			pfree(subxids);
-		}
-	}
 }
 
 const char *
@@ -74,8 +49,6 @@ commit_ts_identify(uint8 info)
 			return "ZEROPAGE";
 		case COMMIT_TS_TRUNCATE:
 			return "TRUNCATE";
-		case COMMIT_TS_SETTS:
-			return "SETTS";
 		default:
 			return NULL;
 	}

src/backend/access/transam/commit_ts.c

@@ -114,9 +114,6 @@ static void ActivateCommitTs(void);
 static void DeactivateCommitTs(void);
 static void WriteZeroPageXlogRec(int pageno);
 static void WriteTruncateXlogRec(int pageno, TransactionId oldestXid);
-static void WriteSetTimestampXlogRec(TransactionId mainxid, int nsubxids,
-									 TransactionId *subxids, TimestampTz timestamp,
-									 RepOriginId nodeid);
 
 /*
  * TransactionTreeSetCommitTsData
@@ -133,18 +130,11 @@ static void WriteSetTimestampXlogRec(TransactionId mainxid, int nsubxids,
  * permanent) so we need to keep the information about them here. If the
  * subtrans implementation changes in the future, we might want to revisit the
  * decision of storing timestamp info for each subxid.
- *
- * The write_xlog parameter tells us whether to include an XLog record of this
- * or not.  Normally, this is called from transaction commit routines (both
- * normal and prepared) and the information will be stored in the transaction
- * commit XLog record, and so they should pass "false" for this.  The XLog redo
- * code should use "false" here as well.  Other callers probably want to pass
- * true, so that the given values persist in case of crashes.
  */
 void
 TransactionTreeSetCommitTsData(TransactionId xid, int nsubxids,
 							   TransactionId *subxids, TimestampTz timestamp,
-							   RepOriginId nodeid, bool write_xlog)
+							   RepOriginId nodeid)
 {
 	int			i;
 	TransactionId headxid;
@@ -161,13 +151,6 @@ TransactionTreeSetCommitTsData(TransactionId xid, int nsubxids,
 	if (!commitTsShared->commitTsActive)
 		return;
 
-	/*
-	 * Comply with the WAL-before-data rule: if caller specified it wants this
-	 * value to be recorded in WAL, do so before touching the data.
-	 */
-	if (write_xlog)
-		WriteSetTimestampXlogRec(xid, nsubxids, subxids, timestamp, nodeid);
-
 	/*
 	 * Figure out the latest Xid in this batch: either the last subxid if
 	 * there's any, otherwise the parent xid.
@@ -993,28 +976,6 @@ WriteTruncateXlogRec(int pageno, TransactionId oldestXid)
 	(void) XLogInsert(RM_COMMIT_TS_ID, COMMIT_TS_TRUNCATE);
 }
 
-/*
- * Write a SETTS xlog record
- */
-static void
-WriteSetTimestampXlogRec(TransactionId mainxid, int nsubxids,
-						 TransactionId *subxids, TimestampTz timestamp,
-						 RepOriginId nodeid)
-{
-	xl_commit_ts_set record;
-
-	record.timestamp = timestamp;
-	record.nodeid = nodeid;
-	record.mainxid = mainxid;
-
-	XLogBeginInsert();
-	XLogRegisterData((char *) &record,
-					 offsetof(xl_commit_ts_set, mainxid) +
-					 sizeof(TransactionId));
-	XLogRegisterData((char *) subxids, nsubxids * sizeof(TransactionId));
-	XLogInsert(RM_COMMIT_TS_ID, COMMIT_TS_SETTS);
-}
-
 /*
  * CommitTS resource manager's routines
  */
@@ -1055,29 +1016,6 @@ commit_ts_redo(XLogReaderState *record)
 
 		SimpleLruTruncate(CommitTsCtl, trunc->pageno);
 	}
-	else if (info == COMMIT_TS_SETTS)
-	{
-		xl_commit_ts_set *setts = (xl_commit_ts_set *) XLogRecGetData(record);
-		int			nsubxids;
-		TransactionId *subxids;
-
-		nsubxids = ((XLogRecGetDataLen(record) - SizeOfCommitTsSet) /
-					sizeof(TransactionId));
-		if (nsubxids > 0)
-		{
-			subxids = palloc(sizeof(TransactionId) * nsubxids);
-			memcpy(subxids,
-				   XLogRecGetData(record) + SizeOfCommitTsSet,
-				   sizeof(TransactionId) * nsubxids);
-		}
-		else
-			subxids = NULL;
-
-		TransactionTreeSetCommitTsData(setts->mainxid, nsubxids, subxids,
-									   setts->timestamp, setts->nodeid, false);
-		if (subxids)
-			pfree(subxids);
-	}
 	else
 		elog(PANIC, "commit_ts_redo: unknown op code %u", info);
 }

src/backend/access/transam/twophase.c

@@ -2246,7 +2246,7 @@ RecordTransactionCommitPrepared(TransactionId xid,
 
 	TransactionTreeSetCommitTsData(xid, nchildren, children,
 								   replorigin_session_origin_timestamp,
-								   replorigin_session_origin, false);
+								   replorigin_session_origin);
 
 	/*
 	 * We don't currently try to sleep before flush here ... nor is there any

src/backend/access/transam/xact.c

@@ -1366,7 +1366,7 @@ RecordTransactionCommit(void)
 
 		TransactionTreeSetCommitTsData(xid, nchildren, children,
 									   replorigin_session_origin_timestamp,
-									   replorigin_session_origin, false);
+									   replorigin_session_origin);
 	}
 
 	/*
@@ -5804,7 +5804,7 @@ xact_redo_commit(xl_xact_parsed_commit *parsed,
 
 	/* Set the transaction commit timestamp and metadata */
 	TransactionTreeSetCommitTsData(xid, parsed->nsubxacts, parsed->subxacts,
-								   commit_time, origin_id, false);
+								   commit_time, origin_id);
 
 	if (standbyState == STANDBY_DISABLED)
 	{

src/include/access/commit_ts.h

@@ -25,7 +25,7 @@ extern bool check_track_commit_timestamp(bool *newval, void **extra,
 
 extern void TransactionTreeSetCommitTsData(TransactionId xid, int nsubxids,
 										   TransactionId *subxids, TimestampTz timestamp,
-										   RepOriginId nodeid, bool write_xlog);
+										   RepOriginId nodeid);
 extern bool TransactionIdGetCommitTsData(TransactionId xid,
 										 TimestampTz *ts, RepOriginId *nodeid);
 extern TransactionId GetLatestCommitTsData(TimestampTz *ts,
@@ -50,7 +50,6 @@ extern int	committssyncfiletag(const FileTag *ftag, char *path);
 /* XLOG stuff */
 #define COMMIT_TS_ZEROPAGE		0x00
 #define COMMIT_TS_TRUNCATE		0x10
-#define COMMIT_TS_SETTS			0x20
 
 typedef struct xl_commit_ts_set
 {

src/include/access/xlog_internal.h

@@ -31,7 +31,7 @@
 /*
  * Each page of XLOG file has a header like this:
  */
-#define XLOG_PAGE_MAGIC 0xD10C	/* can be used as WAL version indicator */
+#define XLOG_PAGE_MAGIC 0xD10D	/* can be used as WAL version indicator */
 
 typedef struct XLogPageHeaderData
 {