diff --git a/libs/walproposer/libpqwalproposer.c b/libs/walproposer/libpqwalproposer.c
index 37ab1e049a..5a50e51d6b 100644
--- a/libs/walproposer/libpqwalproposer.c
+++ b/libs/walproposer/libpqwalproposer.c
@@ -3,6 +3,7 @@
 #include "walproposer.h"
 #include "rust_bindings.h"
 #include "replication/message.h"
+#include "access/xlog_internal.h"
 
 // defined in walproposer.h
 uint64 sim_redo_start_lsn;
@@ -169,6 +170,91 @@ sim_start_replication(XLogRecPtr startptr)
 	}
 }
 
+#define UsableBytesInPage (XLOG_BLCKSZ - SizeOfXLogShortPHD)
+
+static int UsableBytesInSegment =
+		(DEFAULT_XLOG_SEG_SIZE / XLOG_BLCKSZ * UsableBytesInPage) -
+		(SizeOfXLogLongPHD - SizeOfXLogShortPHD);
+
+/*
+ * Converts a "usable byte position" to XLogRecPtr. A usable byte position
+ * is the position starting from the beginning of WAL, excluding all WAL
+ * page headers.
+ */
+static XLogRecPtr
+XLogBytePosToRecPtr(uint64 bytepos)
+{
+	uint64		fullsegs;
+	uint64		fullpages;
+	uint64		bytesleft;
+	uint32		seg_offset;
+	XLogRecPtr	result;
+
+	fullsegs = bytepos / UsableBytesInSegment;
+	bytesleft = bytepos % UsableBytesInSegment;
+
+	if (bytesleft < XLOG_BLCKSZ - SizeOfXLogLongPHD)
+	{
+		/* fits on first page of segment */
+		seg_offset = bytesleft + SizeOfXLogLongPHD;
+	}
+	else
+	{
+		/* account for the first page on segment with long header */
+		seg_offset = XLOG_BLCKSZ;
+		bytesleft -= XLOG_BLCKSZ - SizeOfXLogLongPHD;
+
+		fullpages = bytesleft / UsableBytesInPage;
+		bytesleft = bytesleft % UsableBytesInPage;
+
+		seg_offset += fullpages * XLOG_BLCKSZ + bytesleft + SizeOfXLogShortPHD;
+	}
+
+	XLogSegNoOffsetToRecPtr(fullsegs, seg_offset, wal_segment_size, result);
+
+	return result;
+}
+
+/*
+ * Convert an XLogRecPtr to a "usable byte position".
+ */
+static uint64
+XLogRecPtrToBytePos(XLogRecPtr ptr)
+{
+	uint64		fullsegs;
+	uint32		fullpages;
+	uint32		offset;
+	uint64		result;
+
+	XLByteToSeg(ptr, fullsegs, wal_segment_size);
+
+	fullpages = (XLogSegmentOffset(ptr, wal_segment_size)) / XLOG_BLCKSZ;
+	offset = ptr % XLOG_BLCKSZ;
+
+	if (fullpages == 0)
+	{
+		result = fullsegs * UsableBytesInSegment;
+		if (offset > 0)
+		{
+			Assert(offset >= SizeOfXLogLongPHD);
+			result += offset - SizeOfXLogLongPHD;
+		}
+	}
+	else
+	{
+		result = fullsegs * UsableBytesInSegment +
+			(XLOG_BLCKSZ - SizeOfXLogLongPHD) + /* account for first page */
+			(fullpages - 1) * UsableBytesInPage;	/* full pages */
+		if (offset > 0)
+		{
+			Assert(offset >= SizeOfXLogShortPHD);
+			result += offset - SizeOfXLogShortPHD;
+		}
+	}
+
+	return result;
+}
+
 #define max_rdatas 16
 
 void InitMyInsert();
@@ -231,6 +317,8 @@ MyFinishInsert(RmgrId rmid, uint8 info, uint8 flags)
 	int         size;
 	XLogRecPtr  StartPos;
 	XLogRecPtr  EndPos;
+	uint64		startbytepos;
+	uint64		endbytepos;
 
 	/*
 	 * Note: this function can be called multiple times for the same record.
@@ -305,11 +393,17 @@ MyFinishInsert(RmgrId rmid, uint8 info, uint8 flags)
 	/* All (non xlog-switch) records should contain data. */
 	Assert(size > SizeOfXLogRecord);
 
+	startbytepos = XLogRecPtrToBytePos(CurrBytePos);
+	endbytepos = startbytepos + size;
+
 	// Get the position.
-	StartPos = CurrBytePos;
-	EndPos = StartPos + size;
+	StartPos = XLogBytePosToRecPtr(startbytepos);
+	EndPos = XLogBytePosToRecPtr(startbytepos + size);
 	rechdr->xl_prev = PrevBytePos;
 
+	Assert(XLogRecPtrToBytePos(StartPos) == startbytepos);
+	Assert(XLogRecPtrToBytePos(EndPos) == endbytepos);
+
 	// Update global pointers.
 	CurrBytePos = EndPos;
 	PrevBytePos = StartPos;
@@ -329,25 +423,92 @@ MyFinishInsert(RmgrId rmid, uint8 info, uint8 flags)
 	return EndPos;
 }
 
+#define INSERT_FREESPACE(endptr)	\
+	(((endptr) % XLOG_BLCKSZ == 0) ? 0 : (XLOG_BLCKSZ - (endptr) % XLOG_BLCKSZ))
+
 static void
 MyCopyXLogRecordToWAL(int write_len, XLogRecData *rdata, XLogRecPtr StartPos, XLogRecPtr EndPos)
 {
 	XLogRecPtr	CurrPos;
 	int			written;
+	int			freespace;
 
 	// Write hdr_rdt and `num_rdatas` other datas.
 	CurrPos = StartPos;
+	freespace = INSERT_FREESPACE(CurrPos);
+	written = 0;
+
+	Assert(freespace >= sizeof(uint32));
 
 	while (rdata != NULL)
 	{
 		char	   *rdata_data = rdata->data;
 		int			rdata_len = rdata->len;
 
-		// Assert(CurrPos % XLOG_BLCKSZ >= SizeOfXLogShortPHD || rdata_len == 0);
+		while (rdata_len >= freespace)
+		{
+			char header_buf[SizeOfXLogLongPHD];
+			XLogPageHeader NewPage = (XLogPageHeader) header_buf;
+			
+			Assert(CurrPos % XLOG_BLCKSZ >= SizeOfXLogShortPHD || freespace == 0);
+			XLogWalPropWrite(rdata_data, freespace, CurrPos);
+			rdata_data += freespace;
+			rdata_len -= freespace;
+			written += freespace;
+			CurrPos += freespace;
 
+			// Init new page
+			MemSet(header_buf, 0, SizeOfXLogLongPHD);
+			
+			/*
+			 * Fill the new page's header
+			 */
+			NewPage->xlp_magic = XLOG_PAGE_MAGIC;
+
+			/* NewPage->xlp_info = 0; */	/* done by memset */
+			NewPage->xlp_tli = 1;
+			NewPage->xlp_pageaddr = CurrPos;
+
+			/* NewPage->xlp_rem_len = 0; */	/* done by memset */
+			NewPage->xlp_info |= XLP_BKP_REMOVABLE;
+
+			/*
+			 * If first page of an XLOG segment file, make it a long header.
+			 */
+			if ((XLogSegmentOffset(NewPage->xlp_pageaddr, wal_segment_size)) == 0)
+			{
+				XLogLongPageHeader NewLongPage = (XLogLongPageHeader) NewPage;
+
+				NewLongPage->xlp_sysid = 0;
+				NewLongPage->xlp_seg_size = wal_segment_size;
+				NewLongPage->xlp_xlog_blcksz = XLOG_BLCKSZ;
+				NewPage->xlp_info |= XLP_LONG_HEADER;
+			}
+
+			NewPage->xlp_rem_len = write_len - written;
+			if (NewPage->xlp_rem_len > 0) {
+				NewPage->xlp_info |= XLP_FIRST_IS_CONTRECORD;
+			}
+
+			/* skip over the page header */
+			if (XLogSegmentOffset(CurrPos, wal_segment_size) == 0)
+			{
+				XLogWalPropWrite(header_buf, SizeOfXLogLongPHD, CurrPos);
+				CurrPos += SizeOfXLogLongPHD;
+			}
+			else
+			{
+				XLogWalPropWrite(header_buf, SizeOfXLogShortPHD, CurrPos);
+				CurrPos += SizeOfXLogShortPHD;
+			}
+			freespace = INSERT_FREESPACE(CurrPos);
+		}
+
+		Assert(CurrPos % XLOG_BLCKSZ >= SizeOfXLogShortPHD || rdata_len == 0);
 		XLogWalPropWrite(rdata_data, rdata_len, CurrPos);
 		CurrPos += rdata_len;
 		written += rdata_len;
+		freespace -= rdata_len;
 
 		rdata = rdata->next;
 	}
diff --git a/libs/walproposer/src/simtest/wp_sk.rs b/libs/walproposer/src/simtest/wp_sk.rs
index f6a28122ab..c263b5bd45 100644
--- a/libs/walproposer/src/simtest/wp_sk.rs
+++ b/libs/walproposer/src/simtest/wp_sk.rs
@@ -158,6 +158,7 @@ fn test_simple_schedule() -> anyhow::Result<()> {
 
 #[test]
 fn test_many_tx() -> anyhow::Result<()> {
+    enable_debug();
     let clock = init_logger();
     let mut config = TestConfig::new(Some(clock));
     let test = config.start(1337);