From d045dcb01a7610981f303fe081a04c0ee7a75539 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Thu, 27 Feb 2025 16:58:22 -0500
Subject: [PATCH 01/19] removed lwlsn code and added hooks for the removed
 functions

---
 src/backend/access/transam/xlog.c | 394 +-----------------------------
 src/include/access/xlog.h         |  21 +-
 2 files changed, 17 insertions(+), 398 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 6356b23df33..dee2ad13169 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -138,7 +138,7 @@ int			max_slot_wal_keep_size_mb = -1;
 int			wal_decode_buffer_size = 512 * 1024;
 bool		track_wal_io_timing = false;
 uint64		predefined_sysidentifier;
-int			lastWrittenLsnCacheSize;
+
 
 #ifdef WAL_DEBUG
 bool		XLOG_DEBUG = false;
@@ -207,24 +207,10 @@ const struct config_enum_entry archive_mode_options[] = {
 	{NULL, 0, false}
 };
 
-typedef struct LastWrittenLsnCacheEntry
-{
-	BufferTag	key;
-	XLogRecPtr	lsn;
-	/* double linked list for LRU replacement algorithm */
-	dlist_node	lru_node;
-} LastWrittenLsnCacheEntry;
 
 
-/*
- * Cache of last written LSN for each relation page.
- * Also to provide request LSN for smgrnblocks, smgrexists there is pseudokey=InvalidBlockId which stores LSN of last
- * relation metadata update.
- * Size of the cache is limited by GUC variable lastWrittenLsnCacheSize ("lsn_cache_size"),
- * pages are replaced using LRU algorithm, based on L2-list.
- * Access to this cache is protected by 'LastWrittenLsnLock'.
- */
-static HTAB *lastWrittenLsnCache;
+
+
 
 /*
  * Statistics for current checkpoint are collected in this global struct.
@@ -575,16 +561,7 @@ typedef struct XLogCtlData
 	 */
 	XLogRecPtr	lastFpwDisableRecPtr;
 
-	/*
-	 * Maximal last written LSN for pages not present in lastWrittenLsnCache
-	 */
-	XLogRecPtr  maxLastWrittenLsn;
 
-	/*
-	 * Double linked list to implement LRU replacement policy for last written LSN cache.
-	 * Access to this list as well as to last written LSN cache is protected by 'LastWrittenLsnLock'.
-	 */
-	dlist_head lastWrittenLsnLRU;
 
 	/* neon: copy of startup's RedoStartLSN for walproposer's use */
 	XLogRecPtr	RedoStartLSN;
@@ -764,12 +741,6 @@ static void WALInsertLockAcquireExclusive(void);
 static void WALInsertLockRelease(void);
 static void WALInsertLockUpdateInsertingAt(XLogRecPtr insertingAt);
 
-static XLogRecPtr SetLastWrittenLSNForBlockRangeInternal(XLogRecPtr lsn,
-														 RelFileLocator rlocator,
-														 ForkNumber forknum,
-														 BlockNumber from,
-														 BlockNumber n_blocks);
-
 /*
  * Insert an XLOG record represented by an already-constructed chain of data
  * chunks.  This is a low-level routine; to construct the WAL record header
@@ -4952,8 +4923,8 @@ XLOGCtlShmemSize(void)
 Size
 XLOGShmemSize(void)
 {
-	return XLOGCtlShmemSize() +
-		hash_estimate_size(lastWrittenLsnCacheSize, sizeof(LastWrittenLsnCacheEntry));
+	// Removed LwLSN Size as it is no longer in XLog
+	return XLOGCtlShmemSize();
 }
 
 void
@@ -4985,16 +4956,7 @@ XLOGShmemInit(void)
 	XLogCtl = (XLogCtlData *)
 		ShmemInitStruct("XLOG Ctl", XLOGCtlShmemSize(), &foundXLog);
 
-	if (lastWrittenLsnCacheSize > 0)
-	{
-		static HASHCTL info;
-		info.keysize = sizeof(BufferTag);
-		info.entrysize = sizeof(LastWrittenLsnCacheEntry);
-		lastWrittenLsnCache = ShmemInitHash("last_written_lsn_cache",
-											lastWrittenLsnCacheSize, lastWrittenLsnCacheSize,
-											&info,
-											HASH_ELEM | HASH_BLOBS);
-	}
+
 
 	localControlFile = ControlFile;
 	ControlFile = (ControlFileData *)
@@ -5829,13 +5791,7 @@ StartupXLOG(void)
 	RedoRecPtr = XLogCtl->RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo;
 	doPageWrites = lastFullPageWrites;
 
-	/*
-	 * Setup last written lsn cache, max written LSN.
-	 * Starting from here, we could be modifying pages through REDO, which requires
-	 * the existance of maxLwLsn + LwLsn LRU.
-	 */
-	XLogCtl->maxLastWrittenLsn = RedoRecPtr;
-	dlist_init(&XLogCtl->lastWrittenLsnLRU);
+
 
 	/* REDO */
 	if (InRecovery)
@@ -6682,342 +6638,6 @@ GetInsertRecPtr(void)
 	return recptr;
 }
 
-/*
- * GetLastWrittenLSN -- Returns maximal LSN of written page.
- * It returns an upper bound for the last written LSN of a given page,
- * either from a cached last written LSN or a global maximum last written LSN.
- * If rnode is InvalidOid then we calculate maximum among all cached LSN and maxLastWrittenLsn.
- * If cache is large enough, iterating through all hash items may be rather expensive.
- * But GetLastWrittenLSN(InvalidOid) is used only by neon_dbsize which is not performance critical.
- */
-XLogRecPtr
-GetLastWrittenLSN(RelFileLocator rlocator, ForkNumber forknum, BlockNumber blkno)
-{
-	XLogRecPtr lsn;
-	LastWrittenLsnCacheEntry* entry;
-
-	Assert(lastWrittenLsnCacheSize != 0);
-
-	LWLockAcquire(LastWrittenLsnLock, LW_SHARED);
-
-	/* Maximal last written LSN among all non-cached pages */
-	lsn = XLogCtl->maxLastWrittenLsn;
-
-	if (rlocator.relNumber != InvalidOid)
-	{
-		BufferTag key;
-		key.spcOid = rlocator.spcOid;
-		key.dbOid = rlocator.dbOid;
-		key.relNumber = rlocator.relNumber;
-		key.forkNum = forknum;
-		key.blockNum = blkno;
-		entry = hash_search(lastWrittenLsnCache, &key, HASH_FIND, NULL);
-		if (entry != NULL)
-			lsn = entry->lsn;
-		else
-		{
-			LWLockRelease(LastWrittenLsnLock);
-			LWLockAcquire(LastWrittenLsnLock, LW_EXCLUSIVE);
-			/*
-			 * In case of statements CREATE TABLE AS SELECT... or INSERT FROM SELECT... we are fetching data from source table
-			 * and storing it in destination table. It cause problems with prefetch last-written-lsn is known for the pages of
-			 * source table (which for example happens after compute restart). In this case we get get global value of
-			 * last-written-lsn which is changed frequently as far as we are writing pages of destination table.
-			 * As a result request-lsn for the prefetch and request-let when this page is actually needed are different
-			 * and we got exported prefetch request. So it actually disarms prefetch.
-			 * To prevent that, we re-insert the page with the latest LSN, so that it's
-			 * less likely the LSN for this page will get evicted from the LwLsnCache
-			 * before the page is read.
-			 */
-			 lsn = SetLastWrittenLSNForBlockRangeInternal(lsn, rlocator, forknum, blkno, 1);
-		}
-	}
-	else
-	{
-		HASH_SEQ_STATUS seq;
-		/* Find maximum of all cached LSNs */
-		hash_seq_init(&seq, lastWrittenLsnCache);
-		while ((entry = (LastWrittenLsnCacheEntry *) hash_seq_search(&seq)) != NULL)
-		{
-			if (entry->lsn > lsn)
-				lsn = entry->lsn;
-		}
-	}
-	LWLockRelease(LastWrittenLsnLock);
-
-	return lsn;
-}
-
-/*
- * GetLastWrittenLSN -- Returns maximal LSN of written page.
- * It returns an upper bound for the last written LSN of a given page,
- * either from a cached last written LSN or a global maximum last written LSN.
- * If rnode is InvalidOid then we calculate maximum among all cached LSN and maxLastWrittenLsn.
- * If cache is large enough, iterating through all hash items may be rather expensive.
- * But GetLastWrittenLSN(InvalidOid) is used only by neon_dbsize which is not performance critical.
- */
-void
-GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
-				   BlockNumber blkno, int nblocks, XLogRecPtr *lsns)
-{
-	LastWrittenLsnCacheEntry* entry;
-	XLogRecPtr lsn;
-
-	Assert(lastWrittenLsnCacheSize != 0);
-	Assert(nblocks > 0);
-	Assert(PointerIsValid(lsns));
-
-	LWLockAcquire(LastWrittenLsnLock, LW_SHARED);
-
-	if (relfilenode.relNumber != InvalidOid)
-	{
-		BufferTag key;
-		bool missed_keys = false;
-
-		key.spcOid = relfilenode.spcOid;
-		key.dbOid = relfilenode.dbOid;
-		key.relNumber = relfilenode.relNumber;
-		key.forkNum = forknum;
-
-		for (int i = 0; i < nblocks; i++)
-		{
-			/* Maximal last written LSN among all non-cached pages */
-			key.blockNum = blkno + i;
-
-			entry = hash_search(lastWrittenLsnCache, &key, HASH_FIND, NULL);
-			if (entry != NULL)
-			{
- 				lsns[i] = entry->lsn;
-			}
-			else
-			{
-				/* Mark this block's LSN as missing - we'll update the LwLSN for missing blocks in bulk later */
-				lsns[i] = InvalidXLogRecPtr;
-				missed_keys = true;
-			}
-		}
-
-		/*
-		 * If we had any missing LwLSN entries, we add the missing ones now.
-		 * By doing the insertions in one batch, we decrease lock contention.
-		 */
-		if (missed_keys)
-		{
-			LWLockRelease(LastWrittenLsnLock);
-			LWLockAcquire(LastWrittenLsnLock, LW_EXCLUSIVE);
-
-			lsn = XLogCtl->maxLastWrittenLsn;
-
-			for (int i = 0; i < nblocks; i++)
-			{
-				if (lsns[i] == InvalidXLogRecPtr)
-				{
-					lsns[i] = lsn;
-					SetLastWrittenLSNForBlockRangeInternal(lsn, relfilenode, forknum, blkno + i, 1);
-				}
-			}
-		}
-	}
-	else
-	{
-		HASH_SEQ_STATUS seq;
-		lsn = XLogCtl->maxLastWrittenLsn;
-		/* Find maximum of all cached LSNs */
-		hash_seq_init(&seq, lastWrittenLsnCache);
-		while ((entry = (LastWrittenLsnCacheEntry *) hash_seq_search(&seq)) != NULL)
-		{
-			if (entry->lsn > lsn)
-				lsn = entry->lsn;
-		}
-
-		for (int i = 0; i < nblocks; i++)
-			lsns[i] = lsn;
-	}
-	LWLockRelease(LastWrittenLsnLock);
-}
-
-/*
- * Guts for SetLastWrittenLSNForBlockRange.
- * Caller must ensure LastWrittenLsnLock is held in exclusive mode.
- */
-static XLogRecPtr
-SetLastWrittenLSNForBlockRangeInternal(XLogRecPtr lsn,
-									   RelFileLocator rlocator,
-									   ForkNumber forknum,
-									   BlockNumber from,
-									   BlockNumber n_blocks)
-{
-	if (rlocator.relNumber == InvalidOid)
-	{
-		if (lsn > XLogCtl->maxLastWrittenLsn)
-			XLogCtl->maxLastWrittenLsn = lsn;
-		else
-			lsn = XLogCtl->maxLastWrittenLsn;
-	}
-	else
-	{
-		LastWrittenLsnCacheEntry* entry;
-		BufferTag key;
-		bool found;
-		BlockNumber i;
-
-		key.spcOid = rlocator.spcOid;
-		key.dbOid = rlocator.dbOid;
-		key.relNumber = rlocator.relNumber;
-		key.forkNum = forknum;
-		for (i = 0; i < n_blocks; i++)
-		{
-			key.blockNum = from + i;
-			entry = hash_search(lastWrittenLsnCache, &key, HASH_ENTER, &found);
-			if (found)
-			{
-				if (lsn > entry->lsn)
-					entry->lsn = lsn;
-				else
-					lsn = entry->lsn;
-				/* Unlink from LRU list */
-				dlist_delete(&entry->lru_node);
-			}
-			else
-			{
-				entry->lsn = lsn;
-				if (hash_get_num_entries(lastWrittenLsnCache) > lastWrittenLsnCacheSize)
-				{
-					/* Replace least recently used entry */
-					LastWrittenLsnCacheEntry* victim = dlist_container(LastWrittenLsnCacheEntry, lru_node, dlist_pop_head_node(&XLogCtl->lastWrittenLsnLRU));
-					/* Adjust max LSN for not cached relations/chunks if needed */
-					if (victim->lsn > XLogCtl->maxLastWrittenLsn)
-						XLogCtl->maxLastWrittenLsn = victim->lsn;
-
-					hash_search(lastWrittenLsnCache, victim, HASH_REMOVE, NULL);
-				}
-			}
-			/* Link to the end of LRU list */
-			dlist_push_tail(&XLogCtl->lastWrittenLsnLRU, &entry->lru_node);
-		}
-	}
-	return lsn;
-}
-
-/*
- * SetLastWrittenLSNForBlockRange -- Set maximal LSN of written page range.
- * We maintain cache of last written LSNs with limited size and LRU replacement
- * policy. Keeping last written LSN for each page allows to use old LSN when
- * requesting pages of unchanged or appended relations. Also it is critical for
- * efficient work of prefetch in case massive update operations (like vacuum or remove).
- *
- * rlocator.relNumber can be InvalidOid, in this case maxLastWrittenLsn is updated.
- * SetLastWrittenLsn with dummy rlocator is used by createdb and dbase_redo functions.
- */
-XLogRecPtr
-SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks)
-{
-	if (lsn == InvalidXLogRecPtr || n_blocks == 0 || lastWrittenLsnCacheSize == 0)
-		return lsn;
-
-	LWLockAcquire(LastWrittenLsnLock, LW_EXCLUSIVE);
-	lsn = SetLastWrittenLSNForBlockRangeInternal(lsn, rlocator, forknum, from, n_blocks);
-	LWLockRelease(LastWrittenLsnLock);
-
-	return lsn;
-}
-
-/*
- * SetLastWrittenLSNForBlockv -- Set maximal LSN of pages to their respective
- * LSNs.
- *
- * We maintain cache of last written LSNs with limited size and LRU replacement
- * policy. Keeping last written LSN for each page allows to use old LSN when
- * requesting pages of unchanged or appended relations. Also it is critical for
- * efficient work of prefetch in case massive update operations (like vacuum or remove).
- */
-XLogRecPtr
-SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
-						   ForkNumber forknum, BlockNumber blockno,
-						   int nblocks)
-{
-	LastWrittenLsnCacheEntry* entry;
-	BufferTag	key;
-	bool		found;
-	XLogRecPtr	max = InvalidXLogRecPtr;
-
-	if (lsns == NULL || nblocks == 0 || lastWrittenLsnCacheSize == 0 ||
-		relfilenode.relNumber == InvalidOid)
-		return InvalidXLogRecPtr;
-
-	key.relNumber = relfilenode.relNumber;
-	key.dbOid = relfilenode.dbOid;
-	key.spcOid = relfilenode.spcOid;
-	key.forkNum = forknum;
-
-	LWLockAcquire(LastWrittenLsnLock, LW_EXCLUSIVE);
-
-	for (int i = 0; i < nblocks; i++)
-	{
-		XLogRecPtr	lsn = lsns[i];
-
-		key.blockNum = blockno + i;
-		entry = hash_search(lastWrittenLsnCache, &key, HASH_ENTER, &found);
-		if (found)
-		{
-			if (lsn > entry->lsn)
-				entry->lsn = lsn;
-			else
-				lsn = entry->lsn;
-			/* Unlink from LRU list */
-			dlist_delete(&entry->lru_node);
-		}
-		else
-		{
-			entry->lsn = lsn;
-			if (hash_get_num_entries(lastWrittenLsnCache) > lastWrittenLsnCacheSize)
-			{
-				/* Replace least recently used entry */
-				LastWrittenLsnCacheEntry* victim = dlist_container(LastWrittenLsnCacheEntry, lru_node, dlist_pop_head_node(&XLogCtl->lastWrittenLsnLRU));
-				/* Adjust max LSN for not cached relations/chunks if needed */
-				if (victim->lsn > XLogCtl->maxLastWrittenLsn)
-					XLogCtl->maxLastWrittenLsn = victim->lsn;
-
-				hash_search(lastWrittenLsnCache, victim, HASH_REMOVE, NULL);
-			}
-		}
-		/* Link to the end of LRU list */
-		dlist_push_tail(&XLogCtl->lastWrittenLsnLRU, &entry->lru_node);
-		max = Max(max, lsn);
-	}
-
-	LWLockRelease(LastWrittenLsnLock);
-
-	return max;
-}
-
-/*
- * SetLastWrittenLSNForBlock -- Set maximal LSN for block
- */
-XLogRecPtr
-SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum, BlockNumber blkno)
-{
-	return SetLastWrittenLSNForBlockRange(lsn, rlocator, forknum, blkno, 1);
-}
-
-/*
- * SetLastWrittenLSNForRelation -- Set maximal LSN for relation metadata
- */
-XLogRecPtr
-SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum)
-{
-	return SetLastWrittenLSNForBlock(lsn, rlocator, forknum, REL_METADATA_PSEUDO_BLOCKNO);
-}
-
-/*
- * SetLastWrittenLSNForDatabase -- Set maximal LSN for the whole database
- */
-XLogRecPtr
-SetLastWrittenLSNForDatabase(XLogRecPtr lsn)
-{
-	RelFileLocator dummyNode = {InvalidOid, InvalidOid, InvalidOid};
-	return SetLastWrittenLSNForBlock(lsn, dummyNode, MAIN_FORKNUM, 0);
-}
 
 void
 SetRedoStartLsn(XLogRecPtr RedoStartLSN)
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 3a92973bf2f..b1f6e37d739 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -267,25 +267,24 @@ extern XLogRecPtr GetLastImportantRecPtr(void);
 
 /* neon specifics */
 
-extern XLogRecPtr SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
-extern XLogRecPtr SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
-											 ForkNumber forknum, BlockNumber blockno,
-											 int nblocks);
-extern XLogRecPtr SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks);
-extern XLogRecPtr SetLastWrittenLSNForDatabase(XLogRecPtr lsn);
-extern XLogRecPtr SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
-extern XLogRecPtr GetLastWrittenLSN(RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
-extern void GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
-							   BlockNumber blkno, int nblocks, XLogRecPtr *lsns);
-
 extern void SetRedoStartLsn(XLogRecPtr RedoStartLSN);
 extern XLogRecPtr GetRedoStartLsn(void);
 
+
 extern void SetWalWriterSleeping(bool sleeping);
 
 extern Size WALReadFromBuffers(char *dstbuf, XLogRecPtr startptr, Size count,
 							   TimeLineID tli);
 
+/* Hooks for LwLSN */
+typedef XLogRecPtr (*get_lwlsn_hook_type)(RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
+typedef void (*get_lwlsn_v_hook_type)(RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno, int nblocks, XLogRecPtr *lsns);
+typedef XLogRecPtr (*set_lwlsn_block_range_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks);
+typedef XLogRecPtr (*set_lwlsn_block_v_hook_type)(const XLogRecPtr *lsns, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blockno, int nblocks);
+typedef XLogRecPtr (*set_lwlsn_block_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
+typedef XLogRecPtr (*set_lwlsn_relation_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
+typedef XLogRecPtr (*set_lwlsn_db_hook_type)(XLogRecPtr lsn);
+
 /*
  * Routines used by xlogrecovery.c to call back into xlog.c during recovery.
  */

From 5d209d3a9b50d8531e64528f37e37a8124a20f89 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Fri, 28 Feb 2025 13:00:18 -0500
Subject: [PATCH 02/19] replaced lwlsn fn calls with hook calls

---
 src/backend/access/gin/gininsert.c    |  4 ++--
 src/backend/access/gist/gistbuild.c   |  8 ++++----
 src/backend/access/spgist/spginsert.c |  4 ++--
 src/backend/access/transam/xlog.c     |  7 -------
 src/backend/catalog/storage.c         |  2 +-
 src/backend/commands/dbcommands.c     |  9 +++++----
 src/backend/utils/misc/guc_tables.c   | 18 +++++++++---------
 src/include/access/xlog.h             | 12 ++++++++++--
 8 files changed, 33 insertions(+), 31 deletions(-)

diff --git a/src/backend/access/gin/gininsert.c b/src/backend/access/gin/gininsert.c
index bc82e2df9e8..6a9c77bdc51 100644
--- a/src/backend/access/gin/gininsert.c
+++ b/src/backend/access/gin/gininsert.c
@@ -418,8 +418,8 @@ ginbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 		log_newpage_range(index, MAIN_FORKNUM,
 						  0, RelationGetNumberOfBlocks(index),
 						  true);
-		SetLastWrittenLSNForBlockRange(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-		SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		set_lwlsn_block_range_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
+		set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	smgr_end_unlogged_build(index->rd_smgr);
diff --git a/src/backend/access/gist/gistbuild.c b/src/backend/access/gist/gistbuild.c
index 91ebf84fe2d..feb62489e6e 100644
--- a/src/backend/access/gist/gistbuild.c
+++ b/src/backend/access/gist/gistbuild.c
@@ -340,10 +340,10 @@ gistbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 			log_newpage_range(index, MAIN_FORKNUM,
 							  0, RelationGetNumberOfBlocks(index),
 							  true);
-			SetLastWrittenLSNForBlockRange(XactLastRecEnd,
+			set_lwlsn_block_range_hook(XactLastRecEnd,
 							  index->rd_smgr->smgr_rlocator.locator,
 							  MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-			SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+			set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 		}
 
 		smgr_end_unlogged_build(index->rd_smgr);
@@ -464,9 +464,9 @@ gist_indexsortbuild(GISTBuildState *state)
 	{
 		XLogRecPtr lsn = GetRedoRecPtr();
 
-		SetLastWrittenLSNForBlock(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator,
+		set_lwlsn_block_hook(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator,
 								  MAIN_FORKNUM, GIST_ROOT_BLKNO);
-		SetLastWrittenLSNForRelation(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		set_lwlsn_relation_hook(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	pfree(levelstate);
diff --git a/src/backend/access/spgist/spginsert.c b/src/backend/access/spgist/spginsert.c
index f3652531867..1a3db737c9e 100644
--- a/src/backend/access/spgist/spginsert.c
+++ b/src/backend/access/spgist/spginsert.c
@@ -142,9 +142,9 @@ spgbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 		log_newpage_range(index, MAIN_FORKNUM,
 						  0, RelationGetNumberOfBlocks(index),
 						  true);
-		SetLastWrittenLSNForBlockRange(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator,
+		set_lwlsn_block_range_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator,
 						  MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-		SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	smgr_end_unlogged_build(index->rd_smgr);
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index dee2ad13169..0fd3626280f 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -139,7 +139,6 @@ int			wal_decode_buffer_size = 512 * 1024;
 bool		track_wal_io_timing = false;
 uint64		predefined_sysidentifier;
 
-
 #ifdef WAL_DEBUG
 bool		XLOG_DEBUG = false;
 #endif
@@ -210,8 +209,6 @@ const struct config_enum_entry archive_mode_options[] = {
 
 
 
-
-
 /*
  * Statistics for current checkpoint are collected in this global struct.
  * Because only the checkpointer or a stand-alone backend can perform
@@ -4956,8 +4953,6 @@ XLOGShmemInit(void)
 	XLogCtl = (XLogCtlData *)
 		ShmemInitStruct("XLOG Ctl", XLOGCtlShmemSize(), &foundXLog);
 
-
-
 	localControlFile = ControlFile;
 	ControlFile = (ControlFileData *)
 		ShmemInitStruct("Control File", sizeof(ControlFileData), &foundCFile);
@@ -5791,8 +5786,6 @@ StartupXLOG(void)
 	RedoRecPtr = XLogCtl->RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo;
 	doPageWrites = lastFullPageWrites;
 
-
-
 	/* REDO */
 	if (InRecovery)
 	{
diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c
index a97e7dc25d3..bde9ac18271 100644
--- a/src/backend/catalog/storage.c
+++ b/src/backend/catalog/storage.c
@@ -197,7 +197,7 @@ log_smgrcreate(const RelFileLocator *rlocator, ForkNumber forkNum)
 	XLogBeginInsert();
 	XLogRegisterData((char *) &xlrec, sizeof(xlrec));
 	lsn = XLogInsert(RM_SMGR_ID, XLOG_SMGR_CREATE | XLR_SPECIAL_REL_UPDATE);
-	SetLastWrittenLSNForRelation(lsn, *rlocator, forkNum);
+	set_lwlsn_relation_hook(lsn, *rlocator, forkNum);
 }
 
 /*
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 253c3c36c99..2baf5dbe1b0 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -29,6 +29,7 @@
 #include "access/multixact.h"
 #include "access/tableam.h"
 #include "access/xact.h"
+#include "access/xlog.h"
 #include "access/xloginsert.h"
 #include "access/xlogrecovery.h"
 #include "access/xlogutils.h"
@@ -1515,7 +1516,7 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 		/*
 		 * Update global last written LSN after wal-logging create database command
 		 */
-		SetLastWrittenLSNForDatabase(XactLastRecEnd);
+		set_lwlsn_db_hook(XactLastRecEnd);
 
 		/*
 		 * Close pg_database, but keep lock till commit.
@@ -2182,7 +2183,7 @@ movedb(const char *dbname, const char *tblspcname)
 			lsn = XLogInsert(RM_DBASE_ID,
 							 XLOG_DBASE_CREATE_FILE_COPY | XLR_SPECIAL_REL_UPDATE);
 			// TODO: Do we really need to set the LSN here?
-			SetLastWrittenLSNForDatabase(lsn);
+			set_lwlsn_db_hook(lsn);
 		}
 
 		/*
@@ -3357,7 +3358,7 @@ dbase_redo(XLogReaderState *record)
 		 */
 		{
 			XLogRecPtr	lsn = record->EndRecPtr;
-			SetLastWrittenLSNForDatabase(lsn);
+			set_lwlsn_db_hook(lsn);
 		}
 
 		pfree(src_path);
@@ -3387,7 +3388,7 @@ dbase_redo(XLogReaderState *record)
 		 */
 		{
 			XLogRecPtr	lsn = record->EndRecPtr;
-			SetLastWrittenLSNForDatabase(lsn);
+			set_lwlsn_db_hook(lsn);
 		}
 
 		pfree(dbpath);
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 743be6fcc3e..cb7e46171ae 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -2410,15 +2410,15 @@ struct config_int ConfigureNamesInt[] =
 		check_transaction_buffers, NULL, NULL
 	},
 
-	{
-		{"lsn_cache_size", PGC_POSTMASTER, UNGROUPED,
-			gettext_noop("Size of last written LSN cache used by Neon."),
-			NULL
-		},
-		&lastWrittenLsnCacheSize,
-		128*1024, 1024, INT_MAX,
-		NULL, NULL, NULL
-	},
+	// {
+	// 	{"lsn_cache_size", PGC_POSTMASTER, UNGROUPED,
+	// 		gettext_noop("Size of last written LSN cache used by Neon."),
+	// 		NULL
+	// 	},
+	// 	&lastWrittenLsnCacheSize,
+	// 	128*1024, 1024, INT_MAX,
+	// 	NULL, NULL, NULL
+	// },
 
 	{
 		{"temp_buffers", PGC_USERSET, RESOURCES_MEM,
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index b1f6e37d739..3b0825be58e 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -68,7 +68,6 @@ extern PGDLLIMPORT bool track_wal_io_timing;
 extern PGDLLIMPORT int wal_decode_buffer_size;
 
 extern PGDLLIMPORT int CheckPointSegments;
-extern int  lastWrittenLsnCacheSize;
 
 
 /* Archive modes */
@@ -270,7 +269,6 @@ extern XLogRecPtr GetLastImportantRecPtr(void);
 extern void SetRedoStartLsn(XLogRecPtr RedoStartLSN);
 extern XLogRecPtr GetRedoStartLsn(void);
 
-
 extern void SetWalWriterSleeping(bool sleeping);
 
 extern Size WALReadFromBuffers(char *dstbuf, XLogRecPtr startptr, Size count,
@@ -284,6 +282,16 @@ typedef XLogRecPtr (*set_lwlsn_block_v_hook_type)(const XLogRecPtr *lsns, RelFil
 typedef XLogRecPtr (*set_lwlsn_block_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
 typedef XLogRecPtr (*set_lwlsn_relation_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
 typedef XLogRecPtr (*set_lwlsn_db_hook_type)(XLogRecPtr lsn);
+typedef int (*get_lwlsn_cache_size_type) (void);
+
+extern get_lwlsn_hook_type get_lwlsn_hook;
+extern get_lwlsn_v_hook_type get_lwlsn_v_hook;
+extern set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook;
+extern set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook;
+extern set_lwlsn_block_hook_type set_lwlsn_block_hook;
+extern set_lwlsn_relation_hook_type set_lwlsn_relation_hook;
+extern set_lwlsn_db_hook_type set_lwlsn_db_hook;
+extern get_lwlsn_cache_size_type get_lwlsn_cache_size;
 
 /*
  * Routines used by xlogrecovery.c to call back into xlog.c during recovery.

From af7e7e9a62305e4031c637f0af3bba551295d931 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Fri, 28 Feb 2025 16:33:08 -0500
Subject: [PATCH 03/19] removed unnecessary function name changes, got pg17
 building with lwlsn cache moved to neon ext

---
 src/backend/access/gin/gininsert.c    |   4 +-
 src/backend/access/gist/gistbuild.c   |   8 +-
 src/backend/access/spgist/spginsert.c |   4 +-
 src/backend/access/transam/xlog.c     | 118 ++++++++++++++++++++++++++
 src/backend/catalog/storage.c         |   2 +-
 src/backend/commands/dbcommands.c     |   6 +-
 src/backend/utils/misc/guc_tables.c   |  10 ---
 src/include/access/xlog.h             |  11 +++
 8 files changed, 141 insertions(+), 22 deletions(-)

diff --git a/src/backend/access/gin/gininsert.c b/src/backend/access/gin/gininsert.c
index 6a9c77bdc51..bc82e2df9e8 100644
--- a/src/backend/access/gin/gininsert.c
+++ b/src/backend/access/gin/gininsert.c
@@ -418,8 +418,8 @@ ginbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 		log_newpage_range(index, MAIN_FORKNUM,
 						  0, RelationGetNumberOfBlocks(index),
 						  true);
-		set_lwlsn_block_range_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-		set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		SetLastWrittenLSNForBlockRange(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
+		SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	smgr_end_unlogged_build(index->rd_smgr);
diff --git a/src/backend/access/gist/gistbuild.c b/src/backend/access/gist/gistbuild.c
index feb62489e6e..91ebf84fe2d 100644
--- a/src/backend/access/gist/gistbuild.c
+++ b/src/backend/access/gist/gistbuild.c
@@ -340,10 +340,10 @@ gistbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 			log_newpage_range(index, MAIN_FORKNUM,
 							  0, RelationGetNumberOfBlocks(index),
 							  true);
-			set_lwlsn_block_range_hook(XactLastRecEnd,
+			SetLastWrittenLSNForBlockRange(XactLastRecEnd,
 							  index->rd_smgr->smgr_rlocator.locator,
 							  MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-			set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+			SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 		}
 
 		smgr_end_unlogged_build(index->rd_smgr);
@@ -464,9 +464,9 @@ gist_indexsortbuild(GISTBuildState *state)
 	{
 		XLogRecPtr lsn = GetRedoRecPtr();
 
-		set_lwlsn_block_hook(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator,
+		SetLastWrittenLSNForBlock(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator,
 								  MAIN_FORKNUM, GIST_ROOT_BLKNO);
-		set_lwlsn_relation_hook(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		SetLastWrittenLSNForRelation(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	pfree(levelstate);
diff --git a/src/backend/access/spgist/spginsert.c b/src/backend/access/spgist/spginsert.c
index 1a3db737c9e..f3652531867 100644
--- a/src/backend/access/spgist/spginsert.c
+++ b/src/backend/access/spgist/spginsert.c
@@ -142,9 +142,9 @@ spgbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 		log_newpage_range(index, MAIN_FORKNUM,
 						  0, RelationGetNumberOfBlocks(index),
 						  true);
-		set_lwlsn_block_range_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator,
+		SetLastWrittenLSNForBlockRange(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator,
 						  MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-		set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	smgr_end_unlogged_build(index->rd_smgr);
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 0fd3626280f..e66b3ed7d20 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6631,6 +6631,124 @@ GetInsertRecPtr(void)
 	return recptr;
 }
 
+get_lwlsn_hook_type get_lwlsn_hook = NULL;
+get_lwlsn_v_hook_type get_lwlsn_v_hook = NULL;
+set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook = NULL;
+set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook = NULL;
+set_lwlsn_block_hook_type set_lwlsn_block_hook = NULL;
+set_lwlsn_relation_hook_type set_lwlsn_relation_hook = NULL;
+set_lwlsn_db_hook_type set_lwlsn_db_hook = NULL;
+get_lwlsn_cache_size_type get_lwlsn_cache_size = NULL;
+
+/*
+ * GetLastWrittenLSN -- Returns maximal LSN of written page.
+ * It returns an upper bound for the last written LSN of a given page,
+ * either from a cached last written LSN or a global maximum last written LSN.
+ * If rnode is InvalidOid then we calculate maximum among all cached LSN and maxLastWrittenLsn.
+ * If cache is large enough, iterating through all hash items may be rather expensive.
+ * But GetLastWrittenLSN(InvalidOid) is used only by neon_dbsize which is not performance critical.
+ */
+XLogRecPtr
+GetLastWrittenLSN(RelFileLocator rlocator, ForkNumber forknum, BlockNumber blkno) 
+{
+	if (get_lwlsn_hook) 
+	{
+		get_lwlsn_hook(rlocator, forknum, blkno);
+	}
+}
+
+/*
+ * GetLastWrittenLSN -- Returns maximal LSN of written page.
+ * It returns an upper bound for the last written LSN of a given page,
+ * either from a cached last written LSN or a global maximum last written LSN.
+ * If rnode is InvalidOid then we calculate maximum among all cached LSN and maxLastWrittenLsn.
+ * If cache is large enough, iterating through all hash items may be rather expensive.
+ * But GetLastWrittenLSN(InvalidOid) is used only by neon_dbsize which is not performance critical.
+ */
+void
+GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
+				   BlockNumber blkno, int nblocks, XLogRecPtr *lsns) 
+{
+	if (get_lwlsn_v_hook) 
+	{
+		get_lwlsn_v_hook(relfilenode, forknum, blkno, nblocks, lsns);
+	}
+}
+
+/*
+ * SetLastWrittenLSNForBlockRange -- Set maximal LSN of written page range.
+ * We maintain cache of last written LSNs with limited size and LRU replacement
+ * policy. Keeping last written LSN for each page allows to use old LSN when
+ * requesting pages of unchanged or appended relations. Also it is critical for
+ * efficient work of prefetch in case massive update operations (like vacuum or remove).
+ *
+ * rlocator.relNumber can be InvalidOid, in this case maxLastWrittenLsn is updated.
+ * SetLastWrittenLsn with dummy rlocator is used by createdb and dbase_redo functions.
+ */
+XLogRecPtr
+SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks)
+{
+	if (set_lwlsn_block_range_hook) 
+	{
+		set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
+	}
+}
+
+/*
+ * SetLastWrittenLSNForBlockv -- Set maximal LSN of pages to their respective
+ * LSNs.
+ *
+ * We maintain cache of last written LSNs with limited size and LRU replacement
+ * policy. Keeping last written LSN for each page allows to use old LSN when
+ * requesting pages of unchanged or appended relations. Also it is critical for
+ * efficient work of prefetch in case massive update operations (like vacuum or remove).
+ */
+XLogRecPtr
+SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
+						   ForkNumber forknum, BlockNumber blockno,
+						   int nblocks)
+{
+	if (set_lwlsn_block_v_hook)
+	{
+		set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
+	}
+}
+
+/*
+ * SetLastWrittenLSNForBlock -- Set maximal LSN for block
+ */
+XLogRecPtr
+SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum, BlockNumber blkno)
+{
+	if (set_lwlsn_block_hook)
+	{
+		set_lwlsn_block_hook(lsn, rlocator, forknum, blkno);
+	}
+}
+
+/*
+ * SetLastWrittenLSNForRelation -- Set maximal LSN for relation metadata
+ */
+XLogRecPtr
+SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum)
+{
+	if (set_lwlsn_relation_hook)
+	{
+		set_lwlsn_relation_hook(lsn, rlocator, forknum);
+	}
+}
+
+/*
+ * SetLastWrittenLSNForDatabase -- Set maximal LSN for the whole database
+ */
+XLogRecPtr
+SetLastWrittenLSNForDatabase(XLogRecPtr lsn)
+{
+	if (set_lwlsn_db_hook)
+	{
+		set_lwlsn_db_hook(lsn);
+	}
+}g
 
 void
 SetRedoStartLsn(XLogRecPtr RedoStartLSN)
diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c
index bde9ac18271..a97e7dc25d3 100644
--- a/src/backend/catalog/storage.c
+++ b/src/backend/catalog/storage.c
@@ -197,7 +197,7 @@ log_smgrcreate(const RelFileLocator *rlocator, ForkNumber forkNum)
 	XLogBeginInsert();
 	XLogRegisterData((char *) &xlrec, sizeof(xlrec));
 	lsn = XLogInsert(RM_SMGR_ID, XLOG_SMGR_CREATE | XLR_SPECIAL_REL_UPDATE);
-	set_lwlsn_relation_hook(lsn, *rlocator, forkNum);
+	SetLastWrittenLSNForRelation(lsn, *rlocator, forkNum);
 }
 
 /*
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 2baf5dbe1b0..05c23ff6f53 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1516,7 +1516,7 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 		/*
 		 * Update global last written LSN after wal-logging create database command
 		 */
-		set_lwlsn_db_hook(XactLastRecEnd);
+		SetLastWrittenLSNForDatabase(XactLastRecEnd);
 
 		/*
 		 * Close pg_database, but keep lock till commit.
@@ -2183,7 +2183,7 @@ movedb(const char *dbname, const char *tblspcname)
 			lsn = XLogInsert(RM_DBASE_ID,
 							 XLOG_DBASE_CREATE_FILE_COPY | XLR_SPECIAL_REL_UPDATE);
 			// TODO: Do we really need to set the LSN here?
-			set_lwlsn_db_hook(lsn);
+			SetLastWrittenLSNForDatabase(lsn);
 		}
 
 		/*
@@ -3358,7 +3358,7 @@ dbase_redo(XLogReaderState *record)
 		 */
 		{
 			XLogRecPtr	lsn = record->EndRecPtr;
-			set_lwlsn_db_hook(lsn);
+			SetLastWrittenLSNForDatabase(lsn);
 		}
 
 		pfree(src_path);
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index cb7e46171ae..5ec8d12570d 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -2410,16 +2410,6 @@ struct config_int ConfigureNamesInt[] =
 		check_transaction_buffers, NULL, NULL
 	},
 
-	// {
-	// 	{"lsn_cache_size", PGC_POSTMASTER, UNGROUPED,
-	// 		gettext_noop("Size of last written LSN cache used by Neon."),
-	// 		NULL
-	// 	},
-	// 	&lastWrittenLsnCacheSize,
-	// 	128*1024, 1024, INT_MAX,
-	// 	NULL, NULL, NULL
-	// },
-
 	{
 		{"temp_buffers", PGC_USERSET, RESOURCES_MEM,
 			gettext_noop("Sets the maximum number of temporary buffers used by each session."),
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 3b0825be58e..1f16bcfc10f 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -266,6 +266,17 @@ extern XLogRecPtr GetLastImportantRecPtr(void);
 
 /* neon specifics */
 
+extern XLogRecPtr SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
+extern XLogRecPtr SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
+											 ForkNumber forknum, BlockNumber blockno,
+											 int nblocks);
+extern XLogRecPtr SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks);
+extern XLogRecPtr SetLastWrittenLSNForDatabase(XLogRecPtr lsn);
+extern XLogRecPtr SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
+extern XLogRecPtr GetLastWrittenLSN(RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
+extern void GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
+							   BlockNumber blkno, int nblocks, XLogRecPtr *lsns);
+
 extern void SetRedoStartLsn(XLogRecPtr RedoStartLSN);
 extern XLogRecPtr GetRedoStartLsn(void);
 

From 282ca243337cfa8231e44c3c43d5dd49164c7f56 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Mon, 3 Mar 2025 10:47:38 -0500
Subject: [PATCH 04/19] fixed syntax issues

---
 src/backend/access/transam/xlog.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e66b3ed7d20..adadba432c0 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6748,7 +6748,7 @@ SetLastWrittenLSNForDatabase(XLogRecPtr lsn)
 	{
 		set_lwlsn_db_hook(lsn);
 	}
-}g
+}
 
 void
 SetRedoStartLsn(XLogRecPtr RedoStartLSN)

From 8b83aa1e01e5649be40e464222eb65eb6edba5fd Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Mon, 3 Mar 2025 11:42:47 -0500
Subject: [PATCH 05/19] made setter methods of lwlsn neon-internal only as they
 aren't called in postgres

---
 src/backend/access/transam/xlog.c | 40 ++++---------------------------
 src/include/access/xlog.h         |  3 ---
 2 files changed, 5 insertions(+), 38 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index adadba432c0..db998cbbd0a 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6640,41 +6640,6 @@ set_lwlsn_relation_hook_type set_lwlsn_relation_hook = NULL;
 set_lwlsn_db_hook_type set_lwlsn_db_hook = NULL;
 get_lwlsn_cache_size_type get_lwlsn_cache_size = NULL;
 
-/*
- * GetLastWrittenLSN -- Returns maximal LSN of written page.
- * It returns an upper bound for the last written LSN of a given page,
- * either from a cached last written LSN or a global maximum last written LSN.
- * If rnode is InvalidOid then we calculate maximum among all cached LSN and maxLastWrittenLsn.
- * If cache is large enough, iterating through all hash items may be rather expensive.
- * But GetLastWrittenLSN(InvalidOid) is used only by neon_dbsize which is not performance critical.
- */
-XLogRecPtr
-GetLastWrittenLSN(RelFileLocator rlocator, ForkNumber forknum, BlockNumber blkno) 
-{
-	if (get_lwlsn_hook) 
-	{
-		get_lwlsn_hook(rlocator, forknum, blkno);
-	}
-}
-
-/*
- * GetLastWrittenLSN -- Returns maximal LSN of written page.
- * It returns an upper bound for the last written LSN of a given page,
- * either from a cached last written LSN or a global maximum last written LSN.
- * If rnode is InvalidOid then we calculate maximum among all cached LSN and maxLastWrittenLsn.
- * If cache is large enough, iterating through all hash items may be rather expensive.
- * But GetLastWrittenLSN(InvalidOid) is used only by neon_dbsize which is not performance critical.
- */
-void
-GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
-				   BlockNumber blkno, int nblocks, XLogRecPtr *lsns) 
-{
-	if (get_lwlsn_v_hook) 
-	{
-		get_lwlsn_v_hook(relfilenode, forknum, blkno, nblocks, lsns);
-	}
-}
-
 /*
  * SetLastWrittenLSNForBlockRange -- Set maximal LSN of written page range.
  * We maintain cache of last written LSNs with limited size and LRU replacement
@@ -6692,6 +6657,7 @@ SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumb
 	{
 		set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
 	}
+	return lsn;
 }
 
 /*
@@ -6712,6 +6678,7 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
 	{
 		set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
 	}
+	return lsn;
 }
 
 /*
@@ -6724,6 +6691,7 @@ SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber fo
 	{
 		set_lwlsn_block_hook(lsn, rlocator, forknum, blkno);
 	}
+	return lsn;
 }
 
 /*
@@ -6736,6 +6704,7 @@ SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber
 	{
 		set_lwlsn_relation_hook(lsn, rlocator, forknum);
 	}
+	return lsn;
 }
 
 /*
@@ -6748,6 +6717,7 @@ SetLastWrittenLSNForDatabase(XLogRecPtr lsn)
 	{
 		set_lwlsn_db_hook(lsn);
 	}
+	return lsn;
 }
 
 void
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 1f16bcfc10f..b8e71742e5a 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -273,9 +273,6 @@ extern XLogRecPtr SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLoca
 extern XLogRecPtr SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks);
 extern XLogRecPtr SetLastWrittenLSNForDatabase(XLogRecPtr lsn);
 extern XLogRecPtr SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
-extern XLogRecPtr GetLastWrittenLSN(RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
-extern void GetLastWrittenLSNv(RelFileLocator relfilenode, ForkNumber forknum,
-							   BlockNumber blkno, int nblocks, XLogRecPtr *lsns);
 
 extern void SetRedoStartLsn(XLogRecPtr RedoStartLSN);
 extern XLogRecPtr GetRedoStartLsn(void);

From 623de69a47de8755e4f80bca94a0b5fe57ad6d6c Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Mon, 3 Mar 2025 14:29:50 -0500
Subject: [PATCH 06/19] updated null hook behaviour for
 SetLastWrittenLSNForBlockv

---
 src/backend/access/transam/xlog.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index db998cbbd0a..ede87dd3dd5 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6678,7 +6678,16 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
 	{
 		set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
 	}
-	return lsn;
+	// Behaviour in case the hook is not set. Taken from the implemenatation of SetLastWrittenLSNForBlockv in neon_lwlc.c
+	if (lsns == NULL || nblocks == 0) {
+		return InvalidXLogRecPtr;
+	} else {
+		XLogRecPtr max = InvalidXLogRecPtr;
+		for (int i = 0; i < nblocks; i ++) {
+			max = Max(max, lsns[i]);
+		}
+		return max;
+	}
 }
 
 /*

From 24595554c8c3ec7e0082428d436041d58962ee89 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Tue, 4 Mar 2025 13:04:30 -0500
Subject: [PATCH 07/19] added callback to startup shmem init hook

---
 src/backend/access/transam/xlog.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index ede87dd3dd5..43c9919b725 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -4953,6 +4953,10 @@ XLOGShmemInit(void)
 	XLogCtl = (XLogCtlData *)
 		ShmemInitStruct("XLOG Ctl", XLOGCtlShmemSize(), &foundXLog);
 
+	if (shmem_startup_hook) {
+		shmem_startup_hook();
+	}
+
 	localControlFile = ControlFile;
 	ControlFile = (ControlFileData *)
 		ShmemInitStruct("Control File", sizeof(ControlFileData), &foundCFile);

From ab6693bbfb5a0e33283771d8a14a2e055f2a294c Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Wed, 5 Mar 2025 10:14:11 -0500
Subject: [PATCH 08/19] added missing return statements

---
 src/backend/access/transam/xlog.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 43c9919b725..193ded91a44 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6659,7 +6659,7 @@ SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumb
 {
 	if (set_lwlsn_block_range_hook) 
 	{
-		set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
+		return set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
 	}
 	return lsn;
 }
@@ -6680,7 +6680,7 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
 {
 	if (set_lwlsn_block_v_hook)
 	{
-		set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
+		return set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
 	}
 	// Behaviour in case the hook is not set. Taken from the implemenatation of SetLastWrittenLSNForBlockv in neon_lwlc.c
 	if (lsns == NULL || nblocks == 0) {
@@ -6702,7 +6702,7 @@ SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber fo
 {
 	if (set_lwlsn_block_hook)
 	{
-		set_lwlsn_block_hook(lsn, rlocator, forknum, blkno);
+		return set_lwlsn_block_hook(lsn, rlocator, forknum, blkno);
 	}
 	return lsn;
 }
@@ -6715,7 +6715,7 @@ SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber
 {
 	if (set_lwlsn_relation_hook)
 	{
-		set_lwlsn_relation_hook(lsn, rlocator, forknum);
+		return set_lwlsn_relation_hook(lsn, rlocator, forknum);
 	}
 	return lsn;
 }
@@ -6728,7 +6728,7 @@ SetLastWrittenLSNForDatabase(XLogRecPtr lsn)
 {
 	if (set_lwlsn_db_hook)
 	{
-		set_lwlsn_db_hook(lsn);
+		return et_lwlsn_db_hook(lsn);
 	}
 	return lsn;
 }

From 8f5faea84c244d675d5b6c5cbb5c1cd2fff69b67 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Wed, 5 Mar 2025 10:14:11 -0500
Subject: [PATCH 09/19] i# This is a combination of 2 commits.

added missing return statements
---
 src/backend/access/transam/xlog.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 43c9919b725..4d23c379c89 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6659,7 +6659,7 @@ SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumb
 {
 	if (set_lwlsn_block_range_hook) 
 	{
-		set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
+		return set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
 	}
 	return lsn;
 }
@@ -6680,7 +6680,7 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
 {
 	if (set_lwlsn_block_v_hook)
 	{
-		set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
+		return set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
 	}
 	// Behaviour in case the hook is not set. Taken from the implemenatation of SetLastWrittenLSNForBlockv in neon_lwlc.c
 	if (lsns == NULL || nblocks == 0) {
@@ -6702,7 +6702,7 @@ SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber fo
 {
 	if (set_lwlsn_block_hook)
 	{
-		set_lwlsn_block_hook(lsn, rlocator, forknum, blkno);
+		return set_lwlsn_block_hook(lsn, rlocator, forknum, blkno);
 	}
 	return lsn;
 }
@@ -6715,7 +6715,7 @@ SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber
 {
 	if (set_lwlsn_relation_hook)
 	{
-		set_lwlsn_relation_hook(lsn, rlocator, forknum);
+		return set_lwlsn_relation_hook(lsn, rlocator, forknum);
 	}
 	return lsn;
 }
@@ -6728,7 +6728,7 @@ SetLastWrittenLSNForDatabase(XLogRecPtr lsn)
 {
 	if (set_lwlsn_db_hook)
 	{
-		set_lwlsn_db_hook(lsn);
+		return set_lwlsn_db_hook(lsn);
 	}
 	return lsn;
 }

From 8de5b9ac12e8a740de9304dd00fa955e624d7cdd Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Wed, 5 Mar 2025 10:27:14 -0500
Subject: [PATCH 10/19] fixed return statement for block range

---
 src/backend/access/transam/xlog.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 97779221a91..4d23c379c89 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6660,7 +6660,6 @@ SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumb
 	if (set_lwlsn_block_range_hook) 
 	{
 		return set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
-		return set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
 	}
 	return lsn;
 }

From d9170273924860085eab8097dc381844f2f02fbb Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Thu, 6 Mar 2025 16:35:36 -0500
Subject: [PATCH 11/19] removed shmem hookup call to prevent duplicate memory
 allocations

---
 src/backend/access/transam/xlog.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 4d23c379c89..77c22a459aa 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -4953,10 +4953,6 @@ XLOGShmemInit(void)
 	XLogCtl = (XLogCtlData *)
 		ShmemInitStruct("XLOG Ctl", XLOGCtlShmemSize(), &foundXLog);
 
-	if (shmem_startup_hook) {
-		shmem_startup_hook();
-	}
-
 	localControlFile = ControlFile;
 	ControlFile = (ControlFileData *)
 		ShmemInitStruct("Control File", sizeof(ControlFileData), &foundCFile);

From c28913db6b94f2e73fb8fcce44a283bebb7ae5ef Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Mon, 10 Mar 2025 20:24:40 -0400
Subject: [PATCH 12/19] removed unnecessary changes in dbcommands

---
 src/backend/commands/dbcommands.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 05c23ff6f53..253c3c36c99 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -29,7 +29,6 @@
 #include "access/multixact.h"
 #include "access/tableam.h"
 #include "access/xact.h"
-#include "access/xlog.h"
 #include "access/xloginsert.h"
 #include "access/xlogrecovery.h"
 #include "access/xlogutils.h"
@@ -3388,7 +3387,7 @@ dbase_redo(XLogReaderState *record)
 		 */
 		{
 			XLogRecPtr	lsn = record->EndRecPtr;
-			set_lwlsn_db_hook(lsn);
+			SetLastWrittenLSNForDatabase(lsn);
 		}
 
 		pfree(dbpath);

From cf73c345ff452b5f2deb50d198514616fddbd8ba Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Wed, 12 Mar 2025 11:39:14 -0400
Subject: [PATCH 13/19] added hook to update maxlastwrittenlsn

---
 src/backend/access/transam/xlog.c | 6 ++++++
 src/include/access/xlog.h         | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 77c22a459aa..b80df3f51bd 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -5514,6 +5514,8 @@ readZenithSignalFile(void)
 	}
 }
 
+update_max_lwlsn_hook_type update_max_lwlsn_hook = NULL;
+
 /*
  * This must be called ONCE during postmaster or standalone-backend startup
  */
@@ -5786,6 +5788,10 @@ StartupXLOG(void)
 	RedoRecPtr = XLogCtl->RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo;
 	doPageWrites = lastFullPageWrites;
 
+	if (update_max_lwlsn_hook) {
+		update_max_lwlsn_hook(RedoRecPtr);
+	}
+
 	/* REDO */
 	if (InRecovery)
 	{
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index b8e71742e5a..2c65bf7c37a 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -291,6 +291,7 @@ typedef XLogRecPtr (*set_lwlsn_block_hook_type)(XLogRecPtr lsn, RelFileLocator r
 typedef XLogRecPtr (*set_lwlsn_relation_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
 typedef XLogRecPtr (*set_lwlsn_db_hook_type)(XLogRecPtr lsn);
 typedef int (*get_lwlsn_cache_size_type) (void);
+typedef void (*update_max_lwlsn_hook_type) (XLogRecPtr lsn);
 
 extern get_lwlsn_hook_type get_lwlsn_hook;
 extern get_lwlsn_v_hook_type get_lwlsn_v_hook;
@@ -300,6 +301,7 @@ extern set_lwlsn_block_hook_type set_lwlsn_block_hook;
 extern set_lwlsn_relation_hook_type set_lwlsn_relation_hook;
 extern set_lwlsn_db_hook_type set_lwlsn_db_hook;
 extern get_lwlsn_cache_size_type get_lwlsn_cache_size;
+extern update_max_lwlsn_hook_type update_max_lwlsn_hook;
 
 /*
  * Routines used by xlogrecovery.c to call back into xlog.c during recovery.

From faff7e3b457265c672fd04cb71d364f5ec36ea74 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Wed, 12 Mar 2025 13:26:04 -0400
Subject: [PATCH 14/19] removed unnecesary hooks

---
 src/backend/access/transam/xlog.c | 18 +++---------------
 src/include/access/xlog.h         | 10 ----------
 2 files changed, 3 insertions(+), 25 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index b80df3f51bd..a3e0d097776 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6637,14 +6637,9 @@ GetInsertRecPtr(void)
 	return recptr;
 }
 
-get_lwlsn_hook_type get_lwlsn_hook = NULL;
-get_lwlsn_v_hook_type get_lwlsn_v_hook = NULL;
 set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook = NULL;
 set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook = NULL;
 set_lwlsn_block_hook_type set_lwlsn_block_hook = NULL;
-set_lwlsn_relation_hook_type set_lwlsn_relation_hook = NULL;
-set_lwlsn_db_hook_type set_lwlsn_db_hook = NULL;
-get_lwlsn_cache_size_type get_lwlsn_cache_size = NULL;
 
 /*
  * SetLastWrittenLSNForBlockRange -- Set maximal LSN of written page range.
@@ -6715,11 +6710,7 @@ SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber fo
 XLogRecPtr
 SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum)
 {
-	if (set_lwlsn_relation_hook)
-	{
-		return set_lwlsn_relation_hook(lsn, rlocator, forknum);
-	}
-	return lsn;
+	return SetLastWrittenLSNForBlock(lsn, rlocator, forknum, REL_METADATA_PSEUDO_BLOCKNO);
 }
 
 /*
@@ -6728,11 +6719,8 @@ SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber
 XLogRecPtr
 SetLastWrittenLSNForDatabase(XLogRecPtr lsn)
 {
-	if (set_lwlsn_db_hook)
-	{
-		return set_lwlsn_db_hook(lsn);
-	}
-	return lsn;
+	RelFileLocator dummyNode = {InvalidOid, InvalidOid, InvalidOid};
+	return SetLastWrittenLSNForBlock(lsn, dummyNode, MAIN_FORKNUM, 0);
 }
 
 void
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 2c65bf7c37a..2791076c811 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -283,24 +283,14 @@ extern Size WALReadFromBuffers(char *dstbuf, XLogRecPtr startptr, Size count,
 							   TimeLineID tli);
 
 /* Hooks for LwLSN */
-typedef XLogRecPtr (*get_lwlsn_hook_type)(RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
-typedef void (*get_lwlsn_v_hook_type)(RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno, int nblocks, XLogRecPtr *lsns);
 typedef XLogRecPtr (*set_lwlsn_block_range_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks);
 typedef XLogRecPtr (*set_lwlsn_block_v_hook_type)(const XLogRecPtr *lsns, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blockno, int nblocks);
 typedef XLogRecPtr (*set_lwlsn_block_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
-typedef XLogRecPtr (*set_lwlsn_relation_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
-typedef XLogRecPtr (*set_lwlsn_db_hook_type)(XLogRecPtr lsn);
-typedef int (*get_lwlsn_cache_size_type) (void);
 typedef void (*update_max_lwlsn_hook_type) (XLogRecPtr lsn);
 
-extern get_lwlsn_hook_type get_lwlsn_hook;
-extern get_lwlsn_v_hook_type get_lwlsn_v_hook;
 extern set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook;
 extern set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook;
 extern set_lwlsn_block_hook_type set_lwlsn_block_hook;
-extern set_lwlsn_relation_hook_type set_lwlsn_relation_hook;
-extern set_lwlsn_db_hook_type set_lwlsn_db_hook;
-extern get_lwlsn_cache_size_type get_lwlsn_cache_size;
 extern update_max_lwlsn_hook_type update_max_lwlsn_hook;
 
 /*

From de9e6e84e12181b4ed8559c5cd80807110983198 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Thu, 13 Mar 2025 10:20:28 -0400
Subject: [PATCH 15/19] addressed comments, resolved style issues

---
 src/backend/access/transam/xlog.c | 44 +++++++++++--------------------
 src/backend/storage/ipc/ipci.c    |  2 +-
 src/include/access/xlog.h         |  2 +-
 3 files changed, 18 insertions(+), 30 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index a3e0d097776..35b52054923 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -147,6 +147,13 @@ int			wal_segment_size = DEFAULT_XLOG_SEG_SIZE;
 
 /* NEON: Hook to allow the neon extension to restore running-xacts from CLOG at replica startup */
 restore_running_xacts_callback_t restore_running_xacts_callback;
+
+/* NEON: Hook Definitions that enabled the moving of LastWrittenLSN Cache to the neon extension*/
+update_max_lwlsn_hook_type update_max_lwlsn_hook = NULL;
+set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook = NULL;
+set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook = NULL;
+set_lwlsn_block_hook_type set_lwlsn_block_hook = NULL;
+
 /*
  * Number of WAL insertion locks to use. A higher value allows more insertions
  * to happen concurrently, but adds some CPU overhead to flushing the WAL,
@@ -4864,7 +4871,7 @@ GetActiveWalLevelOnStandby(void)
 	return ControlFile->wal_level;
 }
 
-static Size
+Size
 XLOGCtlShmemSize(void)
 {
 	Size		size;
@@ -4914,16 +4921,6 @@ XLOGCtlShmemSize(void)
 	return size;
 }
 
-/*
- * Initialization of shared memory for XLOG
- */
-Size
-XLOGShmemSize(void)
-{
-	// Removed LwLSN Size as it is no longer in XLog
-	return XLOGCtlShmemSize();
-}
-
 void
 XLOGShmemInit(void)
 {
@@ -5514,8 +5511,6 @@ readZenithSignalFile(void)
 	}
 }
 
-update_max_lwlsn_hook_type update_max_lwlsn_hook = NULL;
-
 /*
  * This must be called ONCE during postmaster or standalone-backend startup
  */
@@ -5788,9 +5783,8 @@ StartupXLOG(void)
 	RedoRecPtr = XLogCtl->RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo;
 	doPageWrites = lastFullPageWrites;
 
-	if (update_max_lwlsn_hook) {
+	if (update_max_lwlsn_hook)
 		update_max_lwlsn_hook(RedoRecPtr);
-	}
 
 	/* REDO */
 	if (InRecovery)
@@ -6637,10 +6631,6 @@ GetInsertRecPtr(void)
 	return recptr;
 }
 
-set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook = NULL;
-set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook = NULL;
-set_lwlsn_block_hook_type set_lwlsn_block_hook = NULL;
-
 /*
  * SetLastWrittenLSNForBlockRange -- Set maximal LSN of written page range.
  * We maintain cache of last written LSNs with limited size and LRU replacement
@@ -6655,9 +6645,8 @@ XLogRecPtr
 SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks)
 {
 	if (set_lwlsn_block_range_hook) 
-	{
 		return set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
-	}
+
 	return lsn;
 }
 
@@ -6676,17 +6665,17 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
 						   int nblocks)
 {
 	if (set_lwlsn_block_v_hook)
-	{
 		return set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
-	}
+
 	// Behaviour in case the hook is not set. Taken from the implemenatation of SetLastWrittenLSNForBlockv in neon_lwlc.c
-	if (lsns == NULL || nblocks == 0) {
+	if (lsns == NULL || nblocks == 0) 
+	{
 		return InvalidXLogRecPtr;
 	} else {
 		XLogRecPtr max = InvalidXLogRecPtr;
-		for (int i = 0; i < nblocks; i ++) {
+		for (int i = 0; i < nblocks; i ++) 
 			max = Max(max, lsns[i]);
-		}
+		
 		return max;
 	}
 }
@@ -6698,9 +6687,8 @@ XLogRecPtr
 SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum, BlockNumber blkno)
 {
 	if (set_lwlsn_block_hook)
-	{
 		return set_lwlsn_block_hook(lsn, rlocator, forknum, blkno);
-	}
+
 	return lsn;
 }
 
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 2100150f01c..3dd65e5b500 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -122,7 +122,7 @@ CalculateShmemSize(int *num_semaphores)
 	size = add_size(size, ProcGlobalShmemSize());
 	size = add_size(size, XLogPrefetchShmemSize());
 	size = add_size(size, VarsupShmemSize());
-	size = add_size(size, XLOGShmemSize());
+	size = add_size(size, XLOGCtlShmemSize());
 	size = add_size(size, XLogRecoveryShmemSize());
 	size = add_size(size, CLOGShmemSize());
 	size = add_size(size, CommitTsShmemSize());
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 2791076c811..949b70d6f31 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -242,7 +242,7 @@ extern uint64 GetSystemIdentifier(void);
 extern char *GetMockAuthenticationNonce(void);
 extern bool DataChecksumsEnabled(void);
 extern XLogRecPtr GetFakeLSNForUnloggedRel(void);
-extern Size XLOGShmemSize(void);
+extern Size XLOGCtlShmemSize(void);
 extern void XLOGShmemInit(void);
 extern void BootStrapXLOG(void);
 extern void InitializeWalConsistencyChecking(void);

From 53fa165b7b83f24db11e711de7ebd594f50e8c82 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Thu, 13 Mar 2025 12:11:17 -0400
Subject: [PATCH 16/19] updated styling

---
 src/backend/access/transam/xlog.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 35b52054923..80aca16c30c 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6667,11 +6667,13 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
 	if (set_lwlsn_block_v_hook)
 		return set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
 
-	// Behaviour in case the hook is not set. Taken from the implemenatation of SetLastWrittenLSNForBlockv in neon_lwlc.c
+	// Behaviour in case the hook is not set
 	if (lsns == NULL || nblocks == 0) 
 	{
 		return InvalidXLogRecPtr;
-	} else {
+	} 
+	else 
+	{
 		XLogRecPtr max = InvalidXLogRecPtr;
 		for (int i = 0; i < nblocks; i ++) 
 			max = Max(max, lsns[i]);

From fecca787abe5213d8195fcaf69c93430e6caba4e Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Thu, 13 Mar 2025 12:32:43 -0400
Subject: [PATCH 17/19] resolved comments, updated description for
 set_lwlsn_block_v

---
 src/backend/access/transam/xlog.c | 14 ++++++++++----
 src/backend/storage/ipc/ipci.c    |  2 +-
 src/include/access/xlog.h         |  2 +-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 80aca16c30c..87dc0ae1bbb 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -148,7 +148,7 @@ int			wal_segment_size = DEFAULT_XLOG_SEG_SIZE;
 /* NEON: Hook to allow the neon extension to restore running-xacts from CLOG at replica startup */
 restore_running_xacts_callback_t restore_running_xacts_callback;
 
-/* NEON: Hook Definitions that enabled the moving of LastWrittenLSN Cache to the neon extension*/
+/* NEON: Hooks to facilitate the last written LSN cache */
 update_max_lwlsn_hook_type update_max_lwlsn_hook = NULL;
 set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook = NULL;
 set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook = NULL;
@@ -4872,7 +4872,7 @@ GetActiveWalLevelOnStandby(void)
 }
 
 Size
-XLOGCtlShmemSize(void)
+XLOGShmemSize(void)
 {
 	Size		size;
 
@@ -4948,7 +4948,7 @@ XLOGShmemInit(void)
 
 
 	XLogCtl = (XLogCtlData *)
-		ShmemInitStruct("XLOG Ctl", XLOGCtlShmemSize(), &foundXLog);
+		ShmemInitStruct("XLOG Ctl", XLOGShmemSize(), &foundXLog);
 
 	localControlFile = ControlFile;
 	ControlFile = (ControlFileData *)
@@ -6667,13 +6667,19 @@ SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
 	if (set_lwlsn_block_v_hook)
 		return set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
 
-	// Behaviour in case the hook is not set
+	// Behavior in case the hook is not set
 	if (lsns == NULL || nblocks == 0) 
 	{
+		// If no valid LSNs were provided, fallback to the InvalidXLogRecPtr
 		return InvalidXLogRecPtr;
 	} 
 	else 
 	{
+		// In the case when the hook is present, we would return the 
+		// maximal LSN of all the given LSNs, taking care to update the
+		// given LSN when it's value is lesser than the one found in the
+		// corresponding entry. As the hook is not present, we just return
+		// the maximal lsn without performing a search in the hash table
 		XLogRecPtr max = InvalidXLogRecPtr;
 		for (int i = 0; i < nblocks; i ++) 
 			max = Max(max, lsns[i]);
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 3dd65e5b500..2100150f01c 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -122,7 +122,7 @@ CalculateShmemSize(int *num_semaphores)
 	size = add_size(size, ProcGlobalShmemSize());
 	size = add_size(size, XLogPrefetchShmemSize());
 	size = add_size(size, VarsupShmemSize());
-	size = add_size(size, XLOGCtlShmemSize());
+	size = add_size(size, XLOGShmemSize());
 	size = add_size(size, XLogRecoveryShmemSize());
 	size = add_size(size, CLOGShmemSize());
 	size = add_size(size, CommitTsShmemSize());
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 949b70d6f31..2791076c811 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -242,7 +242,7 @@ extern uint64 GetSystemIdentifier(void);
 extern char *GetMockAuthenticationNonce(void);
 extern bool DataChecksumsEnabled(void);
 extern XLogRecPtr GetFakeLSNForUnloggedRel(void);
-extern Size XLOGCtlShmemSize(void);
+extern Size XLOGShmemSize(void);
 extern void XLOGShmemInit(void);
 extern void BootStrapXLOG(void);
 extern void InitializeWalConsistencyChecking(void);

From affd399bf3ffce5d5bbca184880d0dee515f5b20 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Fri, 14 Mar 2025 17:10:07 -0400
Subject: [PATCH 18/19] converted all function calls to hook calls

---
 src/backend/access/gin/gininsert.c    |  6 +-
 src/backend/access/gist/gistbuild.c   | 14 +++--
 src/backend/access/spgist/spginsert.c |  8 ++-
 src/backend/access/transam/xlog.c     | 90 +--------------------------
 src/backend/catalog/storage.c         |  3 +-
 src/backend/commands/dbcommands.c     | 12 ++--
 src/include/access/xlog.h             | 12 ++--
 7 files changed, 34 insertions(+), 111 deletions(-)

diff --git a/src/backend/access/gin/gininsert.c b/src/backend/access/gin/gininsert.c
index bc82e2df9e8..64e2562630c 100644
--- a/src/backend/access/gin/gininsert.c
+++ b/src/backend/access/gin/gininsert.c
@@ -418,8 +418,10 @@ ginbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 		log_newpage_range(index, MAIN_FORKNUM,
 						  0, RelationGetNumberOfBlocks(index),
 						  true);
-		SetLastWrittenLSNForBlockRange(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-		SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		if (set_lwlsn_block_range_hook)
+			set_lwlsn_block_range_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
+		if (set_lwlsn_relation_hook)
+			set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	smgr_end_unlogged_build(index->rd_smgr);
diff --git a/src/backend/access/gist/gistbuild.c b/src/backend/access/gist/gistbuild.c
index 91ebf84fe2d..4d1d7e19b1f 100644
--- a/src/backend/access/gist/gistbuild.c
+++ b/src/backend/access/gist/gistbuild.c
@@ -340,10 +340,12 @@ gistbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 			log_newpage_range(index, MAIN_FORKNUM,
 							  0, RelationGetNumberOfBlocks(index),
 							  true);
-			SetLastWrittenLSNForBlockRange(XactLastRecEnd,
+			if (set_lwlsn_block_range_hook)
+				set_lwlsn_block_range_hook(XactLastRecEnd,
 							  index->rd_smgr->smgr_rlocator.locator,
 							  MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-			SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+			if (set_lwlsn_relation_hook)
+				set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 		}
 
 		smgr_end_unlogged_build(index->rd_smgr);
@@ -464,9 +466,11 @@ gist_indexsortbuild(GISTBuildState *state)
 	{
 		XLogRecPtr lsn = GetRedoRecPtr();
 
-		SetLastWrittenLSNForBlock(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator,
-								  MAIN_FORKNUM, GIST_ROOT_BLKNO);
-		SetLastWrittenLSNForRelation(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		if (set_lwlsn_block_hook)
+			set_lwlsn_block_hook(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator,
+									MAIN_FORKNUM, GIST_ROOT_BLKNO);
+		if (set_lwlsn_relation_hook)
+			set_lwlsn_relation_hook(lsn, state->indexrel->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	pfree(levelstate);
diff --git a/src/backend/access/spgist/spginsert.c b/src/backend/access/spgist/spginsert.c
index f3652531867..814f34a3241 100644
--- a/src/backend/access/spgist/spginsert.c
+++ b/src/backend/access/spgist/spginsert.c
@@ -142,9 +142,11 @@ spgbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 		log_newpage_range(index, MAIN_FORKNUM,
 						  0, RelationGetNumberOfBlocks(index),
 						  true);
-		SetLastWrittenLSNForBlockRange(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator,
-						  MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
-		SetLastWrittenLSNForRelation(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
+		if (set_lwlsn_block_range_hook)
+			set_lwlsn_block_range_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator,
+						  	MAIN_FORKNUM, 0, RelationGetNumberOfBlocks(index));
+		if (set_lwlsn_relation_hook)
+			set_lwlsn_relation_hook(XactLastRecEnd, index->rd_smgr->smgr_rlocator.locator, MAIN_FORKNUM);
 	}
 
 	smgr_end_unlogged_build(index->rd_smgr);
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 87dc0ae1bbb..66410be987d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -153,6 +153,8 @@ update_max_lwlsn_hook_type update_max_lwlsn_hook = NULL;
 set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook = NULL;
 set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook = NULL;
 set_lwlsn_block_hook_type set_lwlsn_block_hook = NULL;
+set_lwlsn_relation_hook_type set_lwlsn_relation_hook = NULL;
+set_lwlsn_db_hook_type set_lwlsn_db_hook = NULL;
 
 /*
  * Number of WAL insertion locks to use. A higher value allows more insertions
@@ -6631,94 +6633,6 @@ GetInsertRecPtr(void)
 	return recptr;
 }
 
-/*
- * SetLastWrittenLSNForBlockRange -- Set maximal LSN of written page range.
- * We maintain cache of last written LSNs with limited size and LRU replacement
- * policy. Keeping last written LSN for each page allows to use old LSN when
- * requesting pages of unchanged or appended relations. Also it is critical for
- * efficient work of prefetch in case massive update operations (like vacuum or remove).
- *
- * rlocator.relNumber can be InvalidOid, in this case maxLastWrittenLsn is updated.
- * SetLastWrittenLsn with dummy rlocator is used by createdb and dbase_redo functions.
- */
-XLogRecPtr
-SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks)
-{
-	if (set_lwlsn_block_range_hook) 
-		return set_lwlsn_block_range_hook(lsn, rlocator, forknum, from, n_blocks);
-
-	return lsn;
-}
-
-/*
- * SetLastWrittenLSNForBlockv -- Set maximal LSN of pages to their respective
- * LSNs.
- *
- * We maintain cache of last written LSNs with limited size and LRU replacement
- * policy. Keeping last written LSN for each page allows to use old LSN when
- * requesting pages of unchanged or appended relations. Also it is critical for
- * efficient work of prefetch in case massive update operations (like vacuum or remove).
- */
-XLogRecPtr
-SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
-						   ForkNumber forknum, BlockNumber blockno,
-						   int nblocks)
-{
-	if (set_lwlsn_block_v_hook)
-		return set_lwlsn_block_v_hook(lsns, relfilenode, forknum, blockno, nblocks);
-
-	// Behavior in case the hook is not set
-	if (lsns == NULL || nblocks == 0) 
-	{
-		// If no valid LSNs were provided, fallback to the InvalidXLogRecPtr
-		return InvalidXLogRecPtr;
-	} 
-	else 
-	{
-		// In the case when the hook is present, we would return the 
-		// maximal LSN of all the given LSNs, taking care to update the
-		// given LSN when it's value is lesser than the one found in the
-		// corresponding entry. As the hook is not present, we just return
-		// the maximal lsn without performing a search in the hash table
-		XLogRecPtr max = InvalidXLogRecPtr;
-		for (int i = 0; i < nblocks; i ++) 
-			max = Max(max, lsns[i]);
-		
-		return max;
-	}
-}
-
-/*
- * SetLastWrittenLSNForBlock -- Set maximal LSN for block
- */
-XLogRecPtr
-SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum, BlockNumber blkno)
-{
-	if (set_lwlsn_block_hook)
-		return set_lwlsn_block_hook(lsn, rlocator, forknum, blkno);
-
-	return lsn;
-}
-
-/*
- * SetLastWrittenLSNForRelation -- Set maximal LSN for relation metadata
- */
-XLogRecPtr
-SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator rlocator, ForkNumber forknum)
-{
-	return SetLastWrittenLSNForBlock(lsn, rlocator, forknum, REL_METADATA_PSEUDO_BLOCKNO);
-}
-
-/*
- * SetLastWrittenLSNForDatabase -- Set maximal LSN for the whole database
- */
-XLogRecPtr
-SetLastWrittenLSNForDatabase(XLogRecPtr lsn)
-{
-	RelFileLocator dummyNode = {InvalidOid, InvalidOid, InvalidOid};
-	return SetLastWrittenLSNForBlock(lsn, dummyNode, MAIN_FORKNUM, 0);
-}
-
 void
 SetRedoStartLsn(XLogRecPtr RedoStartLSN)
 {
diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c
index a97e7dc25d3..e0dc76209ce 100644
--- a/src/backend/catalog/storage.c
+++ b/src/backend/catalog/storage.c
@@ -197,7 +197,8 @@ log_smgrcreate(const RelFileLocator *rlocator, ForkNumber forkNum)
 	XLogBeginInsert();
 	XLogRegisterData((char *) &xlrec, sizeof(xlrec));
 	lsn = XLogInsert(RM_SMGR_ID, XLOG_SMGR_CREATE | XLR_SPECIAL_REL_UPDATE);
-	SetLastWrittenLSNForRelation(lsn, *rlocator, forkNum);
+	if (set_lwlsn_relation_hook)
+		set_lwlsn_relation_hook(lsn, *rlocator, forkNum);
 }
 
 /*
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 253c3c36c99..a8b2a116b3a 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1515,7 +1515,8 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 		/*
 		 * Update global last written LSN after wal-logging create database command
 		 */
-		SetLastWrittenLSNForDatabase(XactLastRecEnd);
+		if (set_lwlsn_db_hook)
+			set_lwlsn_db_hook(XactLastRecEnd);
 
 		/*
 		 * Close pg_database, but keep lock till commit.
@@ -2182,7 +2183,8 @@ movedb(const char *dbname, const char *tblspcname)
 			lsn = XLogInsert(RM_DBASE_ID,
 							 XLOG_DBASE_CREATE_FILE_COPY | XLR_SPECIAL_REL_UPDATE);
 			// TODO: Do we really need to set the LSN here?
-			SetLastWrittenLSNForDatabase(lsn);
+			if (set_lwlsn_db_hook)
+				set_lwlsn_db_hook(lsn);
 		}
 
 		/*
@@ -3357,7 +3359,8 @@ dbase_redo(XLogReaderState *record)
 		 */
 		{
 			XLogRecPtr	lsn = record->EndRecPtr;
-			SetLastWrittenLSNForDatabase(lsn);
+			if (set_lwlsn_db_hook)
+				set_lwlsn_db_hook(lsn);
 		}
 
 		pfree(src_path);
@@ -3387,7 +3390,8 @@ dbase_redo(XLogReaderState *record)
 		 */
 		{
 			XLogRecPtr	lsn = record->EndRecPtr;
-			SetLastWrittenLSNForDatabase(lsn);
+			if (set_lwlsn_db_hook)
+				set_lwlsn_db_hook(lsn);
 		}
 
 		pfree(dbpath);
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 2791076c811..0546ea5866a 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -266,14 +266,6 @@ extern XLogRecPtr GetLastImportantRecPtr(void);
 
 /* neon specifics */
 
-extern XLogRecPtr SetLastWrittenLSNForBlock(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
-extern XLogRecPtr SetLastWrittenLSNForBlockv(const XLogRecPtr *lsns, RelFileLocator relfilenode,
-											 ForkNumber forknum, BlockNumber blockno,
-											 int nblocks);
-extern XLogRecPtr SetLastWrittenLSNForBlockRange(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks);
-extern XLogRecPtr SetLastWrittenLSNForDatabase(XLogRecPtr lsn);
-extern XLogRecPtr SetLastWrittenLSNForRelation(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
-
 extern void SetRedoStartLsn(XLogRecPtr RedoStartLSN);
 extern XLogRecPtr GetRedoStartLsn(void);
 
@@ -286,12 +278,16 @@ extern Size WALReadFromBuffers(char *dstbuf, XLogRecPtr startptr, Size count,
 typedef XLogRecPtr (*set_lwlsn_block_range_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks);
 typedef XLogRecPtr (*set_lwlsn_block_v_hook_type)(const XLogRecPtr *lsns, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blockno, int nblocks);
 typedef XLogRecPtr (*set_lwlsn_block_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
+typedef XLogRecPtr (*set_lwlsn_relation_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
+typedef XLogRecPtr (*set_lwlsn_db_hook_type)(XLogRecPtr lsn);
 typedef void (*update_max_lwlsn_hook_type) (XLogRecPtr lsn);
 
 extern set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook;
 extern set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook;
 extern set_lwlsn_block_hook_type set_lwlsn_block_hook;
 extern update_max_lwlsn_hook_type update_max_lwlsn_hook;
+extern set_lwlsn_relation_hook_type set_lwlsn_relation_hook;
+extern set_lwlsn_db_hook_type set_lwlsn_db_hook;
 
 /*
  * Routines used by xlogrecovery.c to call back into xlog.c during recovery.

From f8d62e5450fd0bb3001f940de3450be3ff3d5d13 Mon Sep 17 00:00:00 2001
From: Suhas Thalanki <suhastvs@gmail.com>
Date: Mon, 17 Mar 2025 16:33:11 -0400
Subject: [PATCH 19/19] addressed comments

---
 src/backend/access/transam/xlog.c | 12 ++++++------
 src/backend/commands/dbcommands.c | 15 +++++----------
 src/include/access/xlog.h         | 12 ++++++------
 3 files changed, 17 insertions(+), 22 deletions(-)

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 66410be987d..86287161a21 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -149,12 +149,12 @@ int			wal_segment_size = DEFAULT_XLOG_SEG_SIZE;
 restore_running_xacts_callback_t restore_running_xacts_callback;
 
 /* NEON: Hooks to facilitate the last written LSN cache */
-update_max_lwlsn_hook_type update_max_lwlsn_hook = NULL;
+set_lwlsn_block_hook_type set_lwlsn_block_hook = NULL;
 set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook = NULL;
 set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook = NULL;
-set_lwlsn_block_hook_type set_lwlsn_block_hook = NULL;
-set_lwlsn_relation_hook_type set_lwlsn_relation_hook = NULL;
 set_lwlsn_db_hook_type set_lwlsn_db_hook = NULL;
+set_lwlsn_relation_hook_type set_lwlsn_relation_hook = NULL;
+set_max_lwlsn_hook_type set_max_lwlsn_hook = NULL;
 
 /*
  * Number of WAL insertion locks to use. A higher value allows more insertions
@@ -4950,7 +4950,7 @@ XLOGShmemInit(void)
 
 
 	XLogCtl = (XLogCtlData *)
-		ShmemInitStruct("XLOG Ctl", XLOGShmemSize(), &foundXLog);
+	    ShmemInitStruct("XLOG Ctl", XLOGShmemSize(), &foundXLog);
 
 	localControlFile = ControlFile;
 	ControlFile = (ControlFileData *)
@@ -5785,8 +5785,8 @@ StartupXLOG(void)
 	RedoRecPtr = XLogCtl->RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo;
 	doPageWrites = lastFullPageWrites;
 
-	if (update_max_lwlsn_hook)
-		update_max_lwlsn_hook(RedoRecPtr);
+	if (set_max_lwlsn_hook)
+		set_max_lwlsn_hook(RedoRecPtr);
 
 	/* REDO */
 	if (InRecovery)
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index a8b2a116b3a..a8478e61b43 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -3357,11 +3357,9 @@ dbase_redo(XLogReaderState *record)
 		 * Make sure any future requests to the page server see the new
 		 * database.
 		 */
-		{
-			XLogRecPtr	lsn = record->EndRecPtr;
-			if (set_lwlsn_db_hook)
-				set_lwlsn_db_hook(lsn);
-		}
+		if (set_lwlsn_db_hook)
+			set_lwlsn_db_hook(record->EndRecPtr);
+		
 
 		pfree(src_path);
 		pfree(dst_path);
@@ -3388,11 +3386,8 @@ dbase_redo(XLogReaderState *record)
 		 * Make sure any future requests to the page server see the new
 		 * database.
 		 */
-		{
-			XLogRecPtr	lsn = record->EndRecPtr;
-			if (set_lwlsn_db_hook)
-				set_lwlsn_db_hook(lsn);
-		}
+		if (set_lwlsn_db_hook)
+			set_lwlsn_db_hook(record->EndRecPtr);
 
 		pfree(dbpath);
 	}
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 0546ea5866a..eb1ebf4101d 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -275,19 +275,19 @@ extern Size WALReadFromBuffers(char *dstbuf, XLogRecPtr startptr, Size count,
 							   TimeLineID tli);
 
 /* Hooks for LwLSN */
+typedef XLogRecPtr (*set_lwlsn_block_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
 typedef XLogRecPtr (*set_lwlsn_block_range_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber from, BlockNumber n_blocks);
 typedef XLogRecPtr (*set_lwlsn_block_v_hook_type)(const XLogRecPtr *lsns, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blockno, int nblocks);
-typedef XLogRecPtr (*set_lwlsn_block_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum, BlockNumber blkno);
-typedef XLogRecPtr (*set_lwlsn_relation_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
 typedef XLogRecPtr (*set_lwlsn_db_hook_type)(XLogRecPtr lsn);
-typedef void (*update_max_lwlsn_hook_type) (XLogRecPtr lsn);
+typedef XLogRecPtr (*set_lwlsn_relation_hook_type)(XLogRecPtr lsn, RelFileLocator relfilenode, ForkNumber forknum);
+typedef void (*set_max_lwlsn_hook_type) (XLogRecPtr lsn);
 
+extern set_lwlsn_block_hook_type set_lwlsn_block_hook;
 extern set_lwlsn_block_range_hook_type set_lwlsn_block_range_hook;
 extern set_lwlsn_block_v_hook_type set_lwlsn_block_v_hook;
-extern set_lwlsn_block_hook_type set_lwlsn_block_hook;
-extern update_max_lwlsn_hook_type update_max_lwlsn_hook;
-extern set_lwlsn_relation_hook_type set_lwlsn_relation_hook;
 extern set_lwlsn_db_hook_type set_lwlsn_db_hook;
+extern set_lwlsn_relation_hook_type set_lwlsn_relation_hook;
+extern set_max_lwlsn_hook_type set_max_lwlsn_hook;
 
 /*
  * Routines used by xlogrecovery.c to call back into xlog.c during recovery.