ptrack patch for Postgres 9.5 stable

ptrack_v2.patch

diff --git a/src/backend/access/heap/Makefile b/src/backend/access/heap/Makefile
index b83d496..788c55c 100644
--- a/src/backend/access/heap/Makefile
+++ b/src/backend/access/heap/Makefile
@@ -12,6 +12,6 @@ subdir = src/backend/access/heap
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = heapam.o hio.o pruneheap.o rewriteheap.o syncscan.o tuptoaster.o visibilitymap.o
+OBJS = heapam.o hio.o pruneheap.o rewriteheap.o syncscan.o tuptoaster.o visibilitymap.o ptrack.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/heap/ptrack.c b/src/backend/access/heap/ptrack.c
new file mode 100644
index 0000000..7482a61
--- /dev/null
+++ b/src/backend/access/heap/ptrack.c
@@ -0,0 +1,551 @@
+#include "postgres.h"
+
+#include "access/heapam_xlog.h"
+#include "access/heapam.h"
+#include "access/ptrack.h"
+#include "access/xlog.h"
+#include "access/xlogutils.h"
+#include "access/skey.h"
+#include "access/genam.h"
+#include "catalog/pg_depend.h"
+#include "access/htup_details.h"
+#include "miscadmin.h"
+#include "storage/bufmgr.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/inval.h"
+#include "utils/array.h"
+#include "utils/relfilenodemap.h"
+#include <unistd.h>
+
+/* Effective data size */
+#define MAPSIZE (BLCKSZ - MAXALIGN(SizeOfPageHeaderData))
+
+/* Number of bits allocated for each heap block. */
+#define BITS_PER_HEAPBLOCK 1
+
+/* Number of heap blocks we can represent in one byte. */
+#define HEAPBLOCKS_PER_BYTE 8
+
+#define HEAPBLK_TO_MAPBLOCK(x) ((x) / HEAPBLOCKS_PER_PAGE)
+#define HEAPBLK_TO_MAPBYTE(x) (((x) % HEAPBLOCKS_PER_PAGE) / HEAPBLOCKS_PER_BYTE)
+#define HEAPBLK_TO_MAPBIT(x) ((x) % HEAPBLOCKS_PER_BYTE)
+
+#define HEAPBLOCKS_PER_PAGE (MAPSIZE * HEAPBLOCKS_PER_BYTE)
+
+typedef struct BlockTrack
+{
+	BlockNumber		block_number;
+	RelFileNode		rel;
+} BlockTrack;
+
+static BlockTrack blocks_track[XLR_MAX_BLOCK_ID];
+unsigned int blocks_track_count = 0;
+bool ptrack_enable = false;
+
+static Buffer ptrack_readbuf(RelFileNode rnode, BlockNumber blkno, bool extend);
+static void ptrack_extend(SMgrRelation smgr, BlockNumber nvmblocks);
+static void ptrack_set(BlockNumber heapBlk, Buffer vmBuf);
+void SetPtrackClearLSN(bool set_invalid);
+Datum pg_ptrack_test(PG_FUNCTION_ARGS);
+
+/* Tracking memory block inside critical zone */
+void
+ptrack_add_block(BlockNumber block_number, RelFileNode rel)
+{
+	BlockTrack *bt = &blocks_track[blocks_track_count];
+	bt->block_number = block_number;
+	bt->rel = rel;
+	blocks_track_count++;
+	Assert(blocks_track_count < XLR_MAX_BLOCK_ID);
+}
+
+/* Save tracked memory block after end of critical zone */
+void
+ptrack_save(void)
+{
+	Buffer pbuf = InvalidBuffer;
+	unsigned int i;
+
+	for (i = 0; i < blocks_track_count; i++)
+	{
+		BlockTrack *bt = &blocks_track[i];
+		BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(bt->block_number);
+
+		/* Reuse the old pinned buffer if possible */
+		if (BufferIsValid(pbuf))
+		{
+			if (BufferGetBlockNumber(pbuf) == mapBlock)
+				goto set_bit;
+			else
+				ReleaseBuffer(pbuf);
+		}
+
+		pbuf = ptrack_readbuf(bt->rel, mapBlock, true);
+		set_bit:
+		ptrack_set(bt->block_number, pbuf);
+	}
+	if (pbuf != InvalidBuffer)
+		ReleaseBuffer(pbuf);
+
+	blocks_track_count = 0;
+}
+
+/* Set one bit to buffer */
+void
+ptrack_set(BlockNumber heapBlk, Buffer vmBuf)
+{
+	BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(heapBlk);
+	uint32		mapByte = HEAPBLK_TO_MAPBYTE(heapBlk);
+	uint8		mapBit = HEAPBLK_TO_MAPBIT(heapBlk);
+	Page		page;
+	char	   *map;
+
+	/* Check that we have the right VM page pinned */
+	if (!BufferIsValid(vmBuf) || BufferGetBlockNumber(vmBuf) != mapBlock)
+		elog(ERROR, "wrong VM buffer passed to ptrack_set");
+	page = BufferGetPage(vmBuf);
+	map = PageGetContents(page);
+	LockBuffer(vmBuf, BUFFER_LOCK_SHARE);
+
+	if (!(map[mapByte] & (1 << mapBit)))
+	{
+		/* Bad luck. Take an exclusive lock now after unlock share.*/
+		LockBuffer(vmBuf, BUFFER_LOCK_UNLOCK);
+		LockBuffer(vmBuf, BUFFER_LOCK_EXCLUSIVE);
+		if (!(map[mapByte] & (1 << mapBit)))
+		{
+			START_CRIT_SECTION();
+
+			map[mapByte] |= (1 << mapBit);
+			MarkBufferDirty(vmBuf);
+
+			END_CRIT_SECTION_WITHOUT_TRACK();
+		}
+	}
+
+	LockBuffer(vmBuf, BUFFER_LOCK_UNLOCK);
+}
+
+static Buffer
+ptrack_readbuf(RelFileNode rnode, BlockNumber blkno, bool extend)
+{
+	Buffer		buf;
+
+	SMgrRelation smgr = smgropen(rnode, InvalidBackendId);
+
+	/*
+	 * If we haven't cached the size of the ptrack map fork yet, check it
+	 * first.
+	 */
+	if (smgr->smgr_ptrack_nblocks == InvalidBlockNumber)
+	{
+		if (smgrexists(smgr, PAGESTRACK_FORKNUM))
+			smgr->smgr_ptrack_nblocks = smgrnblocks(smgr,
+													  PAGESTRACK_FORKNUM);
+		else
+			smgr->smgr_ptrack_nblocks = 0;
+	}
+	/* Handle requests beyond EOF */
+	if (blkno >= smgr->smgr_ptrack_nblocks)
+	{
+		if (extend)
+			ptrack_extend(smgr, blkno + 1);
+		else
+			return InvalidBuffer;
+	}
+
+	/*
+	 * Use ZERO_ON_ERROR mode, and initialize the page if necessary. It's
+	 * always safe to clear bits, so it's better to clear corrupt pages than
+	 * error out.
+	 */
+	buf = ReadBufferWithoutRelcache2(smgr, PAGESTRACK_FORKNUM, blkno,
+							 RBM_ZERO_ON_ERROR, NULL);
+
+	if (PageIsNew(BufferGetPage(buf)))
+	{
+		Page pg = BufferGetPage(buf);
+		PageInit(pg, BLCKSZ, 0);
+	}
+	return buf;
+}
+
+static void
+ptrack_extend(SMgrRelation smgr, BlockNumber vm_nblocks)
+{
+	BlockNumber vm_nblocks_now;
+	Page		pg;
+
+	pg = (Page) palloc(BLCKSZ);
+	PageInit(pg, BLCKSZ, 0);
+
+	LockSmgrForExtension(smgr, ExclusiveLock);
+	/*
+	 * Create the file first if it doesn't exist.  If smgr_ptrack_nblocks is
+	 * positive then it must exist, no need for an smgrexists call.
+	 */
+	if ((smgr->smgr_ptrack_nblocks == 0 ||
+		 smgr->smgr_ptrack_nblocks == InvalidBlockNumber) &&
+		!smgrexists(smgr, PAGESTRACK_FORKNUM))
+		smgrcreate(smgr, PAGESTRACK_FORKNUM, false);
+
+	vm_nblocks_now = smgrnblocks(smgr, PAGESTRACK_FORKNUM);
+
+	/* Now extend the file */
+	while (vm_nblocks_now < vm_nblocks)
+	{
+		PageSetChecksumInplace(pg, vm_nblocks_now);
+		smgrextend(smgr, PAGESTRACK_FORKNUM, vm_nblocks_now,
+				   (char *) pg, false);
+		vm_nblocks_now++;
+	}
+	/*
+	 * Send a shared-inval message to force other backends to close any smgr
+	 * references they may have for this rel, which we are about to change.
+	 * This is a useful optimization because it means that backends don't have
+	 * to keep checking for creation or extension of the file, which happens
+	 * infrequently.
+	 */
+	CacheInvalidateSmgr(smgr->smgr_rnode);
+	/* Update local cache with the up-to-date size */
+	smgr->smgr_ptrack_nblocks = vm_nblocks_now;
+
+	pfree(pg);
+
+	UnlockSmgrForExtension(smgr, ExclusiveLock);
+}
+
+/* Clear all ptrack files */
+void
+ptrack_clear(void)
+{
+	HeapTuple tuple;
+	Relation catalog = heap_open(RelationRelationId, AccessShareLock);
+	SysScanDesc scan = systable_beginscan(catalog, InvalidOid, false, NULL, 0, NULL);
+
+	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
+	{
+		BlockNumber nblock;
+		Relation rel = RelationIdGetRelation(HeapTupleGetOid(tuple));
+
+		RelationOpenSmgr(rel);
+		if (rel->rd_smgr == NULL)
+			goto end_rel;
+
+		LockSmgrForExtension(rel->rd_smgr, ExclusiveLock);
+
+		if (rel->rd_smgr->smgr_ptrack_nblocks == InvalidBlockNumber)
+		{
+			if (smgrexists(rel->rd_smgr, PAGESTRACK_FORKNUM))
+				rel->rd_smgr->smgr_ptrack_nblocks = smgrnblocks(rel->rd_smgr,
+														PAGESTRACK_FORKNUM);
+			else
+				rel->rd_smgr->smgr_ptrack_nblocks = 0;
+		}
+
+		for(nblock = 0; nblock < rel->rd_smgr->smgr_ptrack_nblocks; nblock++)
+		{
+			Buffer	buf = ReadBufferExtended(rel, PAGESTRACK_FORKNUM,
+				   nblock, RBM_ZERO_ON_ERROR, NULL);
+			Page page = BufferGetPage(buf);
+			char *map = PageGetContents(page);
+			LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
+			START_CRIT_SECTION();
+			MemSet(map, 0, MAPSIZE);
+			MarkBufferDirty(buf);
+			END_CRIT_SECTION_WITHOUT_TRACK();
+			LockBuffer(buf, BUFFER_LOCK_UNLOCK);
+			ReleaseBuffer(buf);
+		}
+
+		UnlockSmgrForExtension(rel->rd_smgr, ExclusiveLock);
+		end_rel:
+			RelationClose(rel);
+	}
+
+	systable_endscan(scan);
+	heap_close(catalog, AccessShareLock);
+
+	SetPtrackClearLSN(false);
+}
+
+/* Get ptrack file as bytea and clear him */
+bytea *
+ptrack_get_and_clear(Oid tablespace_oid, Oid table_oid)
+{
+	bytea *result = NULL;
+	BlockNumber nblock;
+	if (table_oid == InvalidOid)
+	{
+		elog(WARNING, "InvalidOid");
+		goto full_end;
+	}
+	Relation rel = RelationIdGetRelation(RelidByRelfilenode(tablespace_oid,
+															table_oid));
+
+	if (rel == InvalidRelation)
+	{
+		elog(WARNING, "InvalidRelation");
+		goto full_end;
+	}
+
+	RelationOpenSmgr(rel);
+	if (rel->rd_smgr == NULL)
+		goto end_rel;
+
+	LockSmgrForExtension(rel->rd_smgr, ExclusiveLock);
+
+	if (rel->rd_smgr->smgr_ptrack_nblocks == InvalidBlockNumber)
+	{
+		if (smgrexists(rel->rd_smgr, PAGESTRACK_FORKNUM))
+			rel->rd_smgr->smgr_ptrack_nblocks = smgrnblocks(rel->rd_smgr,
+															PAGESTRACK_FORKNUM);
+		else
+			rel->rd_smgr->smgr_ptrack_nblocks = 0;
+	}
+	if (rel->rd_smgr->smgr_ptrack_nblocks == 0)
+	{
+		UnlockSmgrForExtension(rel->rd_smgr, ExclusiveLock);
+		goto end_rel;
+	}
+	result = (bytea *) palloc(rel->rd_smgr->smgr_ptrack_nblocks*MAPSIZE + VARHDRSZ);
+	SET_VARSIZE(result, rel->rd_smgr->smgr_ptrack_nblocks*MAPSIZE + VARHDRSZ);
+
+	for(nblock = 0; nblock < rel->rd_smgr->smgr_ptrack_nblocks; nblock++)
+	{
+		Buffer	buf = ReadBufferExtended(rel, PAGESTRACK_FORKNUM,
+			   nblock, RBM_ZERO_ON_ERROR, NULL);
+		Page page = BufferGetPage(buf);
+		char *map = PageGetContents(page);
+		LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
+		START_CRIT_SECTION();
+		memcpy(VARDATA(result) + nblock*MAPSIZE, map, MAPSIZE);
+		MemSet(map, 0, MAPSIZE);
+		MarkBufferDirty(buf);
+		END_CRIT_SECTION_WITHOUT_TRACK();
+		LockBuffer(buf, BUFFER_LOCK_UNLOCK);
+		ReleaseBuffer(buf);
+	}
+
+	UnlockSmgrForExtension(rel->rd_smgr, ExclusiveLock);
+	end_rel:
+		RelationClose(rel);
+
+	SetPtrackClearLSN(false);
+	full_end:
+	if (result == NULL)
+	{
+		result = palloc0(VARHDRSZ);
+		SET_VARSIZE(result, VARHDRSZ);
+	}
+
+	return result;
+}
+
+void
+SetPtrackClearLSN(bool set_invalid)
+{
+	int			fd;
+	XLogRecPtr	ptr;
+	if (set_invalid)
+		ptr = InvalidXLogRecPtr;
+	else
+		ptr = GetXLogInsertRecPtr();
+	//LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
+	fd = BasicOpenFile("global/ptrack_control",
+					   O_RDWR | O_CREAT | PG_BINARY,
+					   S_IRUSR | S_IWUSR);
+	if (fd < 0)
+		ereport(PANIC,
+				(errcode_for_file_access(),
+				 errmsg("could not create ptrack control file \"%s\": %m",
+						"global/ptrack_control")));
+
+	errno = 0;
+	if (write(fd, &ptr, sizeof(XLogRecPtr)) != sizeof(XLogRecPtr))
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
+		ereport(PANIC,
+				(errcode_for_file_access(),
+				 errmsg("could not write to ptrack control file: %m")));
+	}
+
+	if (pg_fsync(fd) != 0)
+		ereport(PANIC,
+				(errcode_for_file_access(),
+				 errmsg("could not fsync ptrack control file: %m")));
+
+	if (close(fd))
+		ereport(PANIC,
+				(errcode_for_file_access(),
+				 errmsg("could not close ptrack control file: %m")));
+	//LWLockRelease(ControlFileLock);
+}
+
+/* Test ptrack file */
+Datum
+pg_ptrack_test(PG_FUNCTION_ARGS)
+{
+	Oid relation_oid = PG_GETARG_OID(0);
+	BlockNumber nblock, num_blocks;
+	Relation rel;
+	XLogRecPtr ptrack_control_lsn;
+	Buffer ptrack_buf = InvalidBuffer;
+	Page		page;
+	char	   *map;
+	int			fd;
+	unsigned int excess_data_counter = 0;
+	unsigned int necessary_data_counter = 0;
+	ArrayType *result_array;
+	Datum result_elems[2];
+
+	if (!superuser() && !has_rolreplication(GetUserId()))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+		 (errmsg("must be superuser or replication role to clear ptrack files"))));
+
+	/* get LSN from ptrack_control file */
+	fd = BasicOpenFile("global/ptrack_control",
+					   O_RDONLY | PG_BINARY,
+					   0);
+
+	if (fd < 0)
+		ereport(PANIC,
+				(errcode_for_file_access(),
+				 errmsg("could not open ptrack control file \"%s\": %m",
+						"global/ptrack_control")));
+	errno = 0;
+	if (read(fd, &ptrack_control_lsn, sizeof(XLogRecPtr)) != sizeof(XLogRecPtr))
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
+
+		ereport(PANIC,
+				(errcode_for_file_access(),
+				 errmsg("could not read to ptrack control file: %m")));
+	}
+
+	if (close(fd))
+		ereport(PANIC,
+				(errcode_for_file_access(),
+				 errmsg("could not close ptrack control file: %m")));
+
+	rel = RelationIdGetRelation(relation_oid);
+	if (rel == InvalidRelation)
+	{
+		elog(WARNING, "Relation not found.");
+		goto end_return;
+	}
+	LockRelationOid(relation_oid, AccessShareLock);
+	RelationOpenSmgr(rel);
+	if (rel->rd_smgr == NULL)
+		goto end_rel;
+
+	LockSmgrForExtension(rel->rd_smgr, ExclusiveLock);
+
+	num_blocks = smgrnblocks(rel->rd_smgr, MAIN_FORKNUM);
+	if (rel->rd_smgr->smgr_ptrack_nblocks == InvalidBlockNumber)
+	{
+		if (smgrexists(rel->rd_smgr, PAGESTRACK_FORKNUM))
+			rel->rd_smgr->smgr_ptrack_nblocks = smgrnblocks(rel->rd_smgr, PAGESTRACK_FORKNUM);
+		else
+			rel->rd_smgr->smgr_ptrack_nblocks = 0;
+	}
+
+	for(nblock = 0; nblock < num_blocks; nblock++)
+	{
+		Buffer	main_buf = ReadBufferExtended(rel,
+			MAIN_FORKNUM,
+			nblock,
+			RBM_ZERO_ON_ERROR,
+			NULL);
+		Page main_page;
+		XLogRecPtr	main_page_lsn;
+
+		BlockNumber mapBlock = HEAPBLK_TO_MAPBLOCK(nblock);
+		uint32		mapByte = HEAPBLK_TO_MAPBYTE(nblock);
+		uint8		mapBit = HEAPBLK_TO_MAPBIT(nblock);
+
+		/* Get page lsn */
+		LockBuffer(main_buf, BUFFER_LOCK_SHARE);
+		main_page = BufferGetPage(main_buf);
+		main_page_lsn = PageGetLSN(main_page);
+		LockBuffer(main_buf, BUFFER_LOCK_UNLOCK);
+		ReleaseBuffer(main_buf);
+
+		/* Reuse the old pinned buffer if possible */
+		if (BufferIsValid(ptrack_buf))
+		{
+			if (BufferGetBlockNumber(ptrack_buf) == mapBlock)
+				goto read_bit;
+			else
+				ReleaseBuffer(ptrack_buf);
+		}
+		ptrack_buf = ptrack_readbuf(rel->rd_node, mapBlock, false);
+
+		read_bit:
+		if (ptrack_buf == InvalidBuffer)
+		{
+			/* not tracked data */
+			if(ptrack_control_lsn < main_page_lsn)
+			{
+				necessary_data_counter++;
+				elog(WARNING, "Block %ud not track. Ptrack lsn:%lx page lsn:%lx",
+					nblock,
+					ptrack_control_lsn,
+					main_page_lsn);
+			}
+			else
+				continue;
+		}
+
+		page = BufferGetPage(ptrack_buf);
+		map = PageGetContents(page);
+		LockBuffer(ptrack_buf, BUFFER_LOCK_SHARE);
+		if(map[mapByte] & (1 << mapBit))
+		{
+			/* excess data */
+			if (ptrack_control_lsn >= main_page_lsn)
+			{
+				excess_data_counter++;
+				elog(WARNING, "Block %ud not needed. Ptrack lsn:%lx page lsn:%lx",
+					nblock,
+					ptrack_control_lsn,
+					main_page_lsn);
+			}
+		}
+		/* not tracked data */
+		else if (ptrack_control_lsn < main_page_lsn)
+		{
+			necessary_data_counter++;
+			elog(WARNING, "Block %ud not tracked. Ptrack lsn:%lx page lsn:%lx",
+				nblock,
+				ptrack_control_lsn,
+				main_page_lsn);
+		}
+		LockBuffer(ptrack_buf, BUFFER_LOCK_UNLOCK);
+	}
+
+	end_rel:
+	if (ptrack_buf != InvalidBuffer)
+		ReleaseBuffer(ptrack_buf);
+	RelationClose(rel);
+	UnlockRelationOid(relation_oid, AccessShareLock);
+
+	end_return:
+	result_elems[0] = UInt32GetDatum(excess_data_counter);
+	result_elems[1] = UInt32GetDatum(necessary_data_counter);
+	result_array = construct_array(result_elems, 2, 23, 4, true, 'i');
+	PG_RETURN_ARRAYTYPE_P(result_array);
+}
+
+void
+assign_ptrack_enable(bool newval, void *extra)
+{
+	if(DataDir != NULL && !IsBootstrapProcessingMode() && !newval)
+		SetPtrackClearLSN(true);
+}
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index f983d79..af06fcd 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6674,6 +6674,7 @@ StartupXLOG(void)
 			do
 			{
 				bool		switchedTLI = false;
+				int nblock;
 
 #ifdef WAL_DEBUG
 				if (XLOG_DEBUG ||
@@ -6827,6 +6828,17 @@ StartupXLOG(void)
 				/* Pop the error context stack */
 				error_context_stack = errcallback.previous;
 
+				if (ptrack_enable)
+					for(nblock = 0; nblock < xlogreader->max_block_id; nblock++)
+					{
+						if(xlogreader->blocks[nblock].forknum == MAIN_FORKNUM)
+						{
+							ptrack_add_block(xlogreader->blocks[nblock].blkno,
+											xlogreader->blocks[nblock].rnode);
+							ptrack_save();
+						}
+					}
+
 				/*
 				 * Update lastReplayedEndRecPtr after this record has been
 				 * successfully replayed.
diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c
index 329bb8c..5550396 100644
--- a/src/backend/access/transam/xlogfuncs.c
+++ b/src/backend/access/transam/xlogfuncs.c
@@ -102,6 +102,30 @@ pg_stop_backup(PG_FUNCTION_ARGS)
 	PG_RETURN_LSN(stoppoint);
 }
 
+Datum
+pg_ptrack_clear(PG_FUNCTION_ARGS)
+{
+	if (!superuser() && !has_rolreplication(GetUserId()))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+		 (errmsg("must be superuser or replication role to clear ptrack files"))));
+
+	ptrack_clear();
+
+	PG_RETURN_VOID();
+}
+
+Datum
+pg_ptrack_get_and_clear(PG_FUNCTION_ARGS)
+{
+	if (!superuser() && !has_rolreplication(GetUserId()))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+		 (errmsg("must be superuser or replication role to clear ptrack files"))));
+
+	PG_RETURN_BYTEA_P(ptrack_get_and_clear(PG_GETARG_OID(0), PG_GETARG_OID(1)));
+}
+
 /*
  * pg_switch_xlog: switch to next xlog file
  */
diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c
index 925c430..265d0f0 100644
--- a/src/backend/access/transam/xloginsert.c
+++ b/src/backend/access/transam/xloginsert.c
@@ -23,6 +23,7 @@
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "access/xloginsert.h"
+#include "access/ptrack.h"
 #include "catalog/pg_control.h"
 #include "common/pg_lzcompress.h"
 #include "miscadmin.h"
@@ -256,6 +257,10 @@ XLogRegisterBuffer(uint8 block_id, Buffer buffer, uint8 flags)
 #endif
 
 	regbuf->in_use = true;
+	if (ptrack_enable && regbuf->forkno == MAIN_FORKNUM)
+	{
+		ptrack_add_block(regbuf->block, regbuf->rnode);
+	}
 }
 
 /*
diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c
index d4440c9..a49ab8b 100644
--- a/src/backend/catalog/storage.c
+++ b/src/backend/catalog/storage.c
@@ -238,6 +238,7 @@ RelationTruncate(Relation rel, BlockNumber nblocks)
 	rel->rd_smgr->smgr_targblock = InvalidBlockNumber;
 	rel->rd_smgr->smgr_fsm_nblocks = InvalidBlockNumber;
 	rel->rd_smgr->smgr_vm_nblocks = InvalidBlockNumber;
+	rel->rd_smgr->smgr_ptrack_nblocks = InvalidBlockNumber;
 
 	/* Truncate the FSM first if it exists */
 	fsm = smgrexists(rel->rd_smgr, FSM_FORKNUM);
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 3647918..780c96d 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -593,6 +593,17 @@ ReadBufferWithoutRelcache(RelFileNode rnode, ForkNumber forkNum,
 							 mode, strategy, &hit);
 }
 
+Buffer
+ReadBufferWithoutRelcache2(SMgrRelation smgr, ForkNumber forkNum,
+						  BlockNumber blockNum, ReadBufferMode mode,
+						  BufferAccessStrategy strategy)
+{
+	bool		hit;
+
+	return ReadBuffer_common(smgr, RELPERSISTENCE_PERMANENT, forkNum, blockNum,
+							 mode, strategy, &hit);
+}
+
 
 /*
  * ReadBuffer_common -- common logic for all ReadBuffer variants
diff --git a/src/backend/storage/lmgr/lmgr.c b/src/backend/storage/lmgr/lmgr.c
index c052949..07306a3 100644
--- a/src/backend/storage/lmgr/lmgr.c
+++ b/src/backend/storage/lmgr/lmgr.c
@@ -355,6 +355,30 @@ UnlockRelationForExtension(Relation relation, LOCKMODE lockmode)
 	LockRelease(&tag, lockmode, false);
 }
 
+void
+LockSmgrForExtension(SMgrRelation smgr, LOCKMODE lockmode)
+{
+	LOCKTAG		tag;
+
+	SET_LOCKTAG_SMGR(tag, smgr->smgr_rnode.node.relNode);
+
+	(void) LockAcquire(&tag, lockmode, false, false);
+}
+
+/*
+ *		UnlockRelationForExtension
+ */
+void
+UnlockSmgrForExtension(SMgrRelation smgr, LOCKMODE lockmode)
+{
+	LOCKTAG		tag;
+
+	SET_LOCKTAG_SMGR(tag ,smgr->smgr_rnode.node.relNode);
+
+	LockRelease(&tag, lockmode, false);
+}
+
+
 /*
  *		LockPage
  *
@@ -987,6 +1011,11 @@ DescribeLockTag(StringInfo buf, const LOCKTAG *tag)
 							 tag->locktag_field3,
 							 tag->locktag_field4);
 			break;
+		case LOCKTAG_SMGR:
+			appendStringInfo(buf,
+							 _("smgr lock %u"),
+							 tag->locktag_field1);
+			break;
 		default:
 			appendStringInfo(buf,
 							 _("unrecognized locktag type %d"),
diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c
index 244b4ea..7156894 100644
--- a/src/backend/storage/smgr/smgr.c
+++ b/src/backend/storage/smgr/smgr.c
@@ -168,6 +168,7 @@ smgropen(RelFileNode rnode, BackendId backend)
 		reln->smgr_targblock = InvalidBlockNumber;
 		reln->smgr_fsm_nblocks = InvalidBlockNumber;
 		reln->smgr_vm_nblocks = InvalidBlockNumber;
+		reln->smgr_ptrack_nblocks = InvalidBlockNumber;
 		reln->smgr_which = 0;	/* we only have md.c at present */
 
 		/* mark it not open */
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 5dba5d2..a0d472d 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -24,6 +24,7 @@
 #include "access/sysattr.h"
 #include "access/xact.h"
 #include "access/xlog.h"
+#include "access/ptrack.h"
 #include "catalog/catalog.h"
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
@@ -552,6 +553,8 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 
 	elog(DEBUG3, "InitPostgres");
 
+	assign_ptrack_enable(ptrack_enable, NULL);
+
 	/*
 	 * Add my PGPROC struct to the ProcArray.
 	 *
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index f249b390..ffa71de 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -31,6 +31,7 @@
 #include "access/transam.h"
 #include "access/twophase.h"
 #include "access/xact.h"
+#include "access/ptrack.h"
 #include "catalog/namespace.h"
 #include "commands/async.h"
 #include "commands/prepare.h"
@@ -987,6 +988,16 @@ static struct config_bool ConfigureNamesBool[] =
 	},
 
 	{
+		{"ptrack_enable", PGC_SU_BACKEND, WAL_SETTINGS,
+			gettext_noop("Enable page tracking."),
+			NULL
+		},
+		&ptrack_enable,
+		false,
+		NULL, &assign_ptrack_enable, NULL
+	},
+
+	{
 		{"wal_compression", PGC_SUSET, WAL_SETTINGS,
 			gettext_noop("Compresses full-page writes written in WAL file."),
 			NULL
diff --git a/src/common/relpath.c b/src/common/relpath.c
index 66dfef1..8adb891 100644
--- a/src/common/relpath.c
+++ b/src/common/relpath.c
@@ -35,7 +35,8 @@ const char *const forkNames[] = {
 	"main",						/* MAIN_FORKNUM */
 	"fsm",						/* FSM_FORKNUM */
 	"vm",						/* VISIBILITYMAP_FORKNUM */
-	"init"						/* INIT_FORKNUM */
+	"init",						/* INIT_FORKNUM */
+	"ptrack"					/* PAGESTRACK_FORKNUM */
 };
 
 /*
diff --git a/src/include/access/ptrack.h b/src/include/access/ptrack.h
new file mode 100644
index 0000000..3421478
--- /dev/null
+++ b/src/include/access/ptrack.h
@@ -0,0 +1,22 @@
+#ifndef PTRACK_H
+#define PTRACK_H
+
+#include "access/xlogdefs.h"
+#include "storage/block.h"
+#include "storage/buf.h"
+#include "storage/relfilenode.h"
+#include "utils/relcache.h"
+
+extern unsigned int blocks_track_count;
+
+extern bool ptrack_enable;
+
+extern void ptrack_save(void);
+
+extern void ptrack_add_block(BlockNumber block_number, RelFileNode rel);
+
+extern void ptrack_clear(void);
+extern bytea *ptrack_get_and_clear(Oid tablespace_oid, Oid table_oid);
+extern void assign_ptrack_enable(bool newval, void *extra);
+
+#endif   /* PTRACK_H */
diff --git a/src/include/access/xlog_fn.h b/src/include/access/xlog_fn.h
index 3ebe966..c669ea2 100644
--- a/src/include/access/xlog_fn.h
+++ b/src/include/access/xlog_fn.h
@@ -15,6 +15,7 @@
 
 extern Datum pg_start_backup(PG_FUNCTION_ARGS);
 extern Datum pg_stop_backup(PG_FUNCTION_ARGS);
+extern Datum pg_ptrack_clear(PG_FUNCTION_ARGS);
 extern Datum pg_switch_xlog(PG_FUNCTION_ARGS);
 extern Datum pg_create_restore_point(PG_FUNCTION_ARGS);
 extern Datum pg_current_xlog_location(PG_FUNCTION_ARGS);
@@ -31,5 +32,6 @@ extern Datum pg_is_xlog_replay_paused(PG_FUNCTION_ARGS);
 extern Datum pg_xlog_location_diff(PG_FUNCTION_ARGS);
 extern Datum pg_is_in_backup(PG_FUNCTION_ARGS);
 extern Datum pg_backup_start_time(PG_FUNCTION_ARGS);
+extern Datum pg_ptrack_test(PG_FUNCTION_ARGS);
 
 #endif   /* XLOG_FN_H */
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 691fa6c..8b2a737 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -3143,6 +3143,12 @@ DATA(insert OID = 3814 ( pg_backup_start_time		PGNSP PGUID 12 1 0 0 0 f f f f t
 DESCR("start time of an online backup");
 DATA(insert OID = 2848 ( pg_switch_xlog			PGNSP PGUID 12 1 0 0 0 f f f f t f v 0 0 3220 "" _null_ _null_ _null_ _null_ _null_ pg_switch_xlog _null_ _null_ _null_ ));
 DESCR("switch to new xlog file");
+DATA(insert OID = 6016 ( pg_ptrack_clear		PGNSP PGUID 12 1 0 0 0 f f f f t f v 0 0 2278 "" _null_ _null_ _null_ _null_ _null_ pg_ptrack_clear _null_ _null_ _null_ ));
+DESCR("clear ptrack fork files");
+DATA(insert OID = 6017 ( pg_ptrack_test		PGNSP PGUID 12 1 0 0 0 f f f f t f v 1 0 1007 "26" _null_ _null_ _null_ _null_ _null_ pg_ptrack_test _null_ _null_ _null_ ));
+DESCR("test ptrack fork relation");
+DATA(insert OID = 6018 ( pg_ptrack_get_and_clear		PGNSP PGUID 12 1 0 0 0 f f f f t f v 2 0 17 "26 26" _null_ _null_ _null_ _null_ _null_ pg_ptrack_get_and_clear _null_ _null_ _null_ ));
+DESCR("get ptrack file as bytea and clear him");
 DATA(insert OID = 3098 ( pg_create_restore_point	PGNSP PGUID 12 1 0 0 0 f f f f t f v 1 0 3220 "25" _null_ _null_ _null_ _null_ _null_ pg_create_restore_point _null_ _null_ _null_ ));
 DESCR("create a named restore point");
 DATA(insert OID = 2849 ( pg_current_xlog_location	PGNSP PGUID 12 1 0 0 0 f f f f t f v 0 0 3220 "" _null_ _null_ _null_ _null_ _null_ pg_current_xlog_location _null_ _null_ _null_ ));
diff --git a/src/include/common/relpath.h b/src/include/common/relpath.h
index a263779..be68567 100644
--- a/src/include/common/relpath.h
+++ b/src/include/common/relpath.h
@@ -27,7 +27,8 @@ typedef enum ForkNumber
 	MAIN_FORKNUM = 0,
 	FSM_FORKNUM,
 	VISIBILITYMAP_FORKNUM,
-	INIT_FORKNUM
+	INIT_FORKNUM,
+	PAGESTRACK_FORKNUM
 
 	/*
 	 * NOTE: if you add a new fork, change MAX_FORKNUM and possibly
@@ -36,9 +37,9 @@ typedef enum ForkNumber
 	 */
 } ForkNumber;
 
-#define MAX_FORKNUM		INIT_FORKNUM
+#define MAX_FORKNUM		PAGESTRACK_FORKNUM
 
-#define FORKNAMECHARS	4		/* max chars for a fork name */
+#define FORKNAMECHARS	6		/* max chars for a fork name */
 
 extern const char *const forkNames[];
 
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index e0d464e..8a71c4d 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -24,6 +24,7 @@
 #define MISCADMIN_H
 
 #include "pgtime.h"				/* for pg_time_t */
+#include "access/ptrack.h"
 
 
 #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
@@ -132,6 +133,14 @@ do { \
 do { \
 	Assert(CritSectionCount > 0); \
 	CritSectionCount--; \
+	if (!CritSectionCount  && ptrack_enable && blocks_track_count > 0) \
+		ptrack_save(); \
+} while(0)
+
+#define END_CRIT_SECTION_WITHOUT_TRACK() \
+do { \
+	Assert(CritSectionCount > 0); \
+	CritSectionCount--; \
 } while(0)
 
 
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 175339b..78d697f 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -18,6 +18,7 @@
 #include "storage/buf.h"
 #include "storage/bufpage.h"
 #include "storage/relfilenode.h"
+#include "storage/smgr.h"
 #include "utils/relcache.h"
 
 typedef void *Block;
@@ -153,6 +154,10 @@ extern Buffer ReadBufferExtended(Relation reln, ForkNumber forkNum,
 extern Buffer ReadBufferWithoutRelcache(RelFileNode rnode,
 						  ForkNumber forkNum, BlockNumber blockNum,
 						  ReadBufferMode mode, BufferAccessStrategy strategy);
+extern Buffer ReadBufferWithoutRelcache2(SMgrRelation smgr,
+						  ForkNumber forkNum, BlockNumber blockNum,
+						  ReadBufferMode mode, BufferAccessStrategy strategy);
+
 extern void ReleaseBuffer(Buffer buffer);
 extern void UnlockReleaseBuffer(Buffer buffer);
 extern void MarkBufferDirty(Buffer buffer);
diff --git a/src/include/storage/lmgr.h b/src/include/storage/lmgr.h
index e7ccce2..8c62f77 100644
--- a/src/include/storage/lmgr.h
+++ b/src/include/storage/lmgr.h
@@ -17,6 +17,7 @@
 #include "lib/stringinfo.h"
 #include "storage/itemptr.h"
 #include "storage/lock.h"
+#include "storage/smgr.h"
 #include "utils/rel.h"
 
 
@@ -54,6 +55,9 @@ extern void UnlockRelationIdForSession(LockRelId *relid, LOCKMODE lockmode);
 extern void LockRelationForExtension(Relation relation, LOCKMODE lockmode);
 extern void UnlockRelationForExtension(Relation relation, LOCKMODE lockmode);
 
+extern void LockSmgrForExtension(SMgrRelation smgr, LOCKMODE lockmode);
+extern void UnlockSmgrForExtension(SMgrRelation smgr, LOCKMODE lockmode);
+
 /* Lock a page (currently only used within indexes) */
 extern void LockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode);
 extern bool ConditionalLockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode);
diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h
index 96fe3a6..00637b4 100644
--- a/src/include/storage/lock.h
+++ b/src/include/storage/lock.h
@@ -187,7 +187,8 @@ typedef enum LockTagType
 	 * Also, we use DB OID = 0 for shared objects such as tablespaces.
 	 */
 	LOCKTAG_USERLOCK,			/* reserved for old contrib/userlock code */
-	LOCKTAG_ADVISORY			/* advisory user locks */
+	LOCKTAG_ADVISORY,			/* advisory user locks */
+	LOCKTAG_SMGR /**/
 } LockTagType;
 
 #define LOCKTAG_LAST_TYPE	LOCKTAG_ADVISORY
@@ -231,6 +232,14 @@ typedef struct LOCKTAG
 	 (locktag).locktag_type = LOCKTAG_RELATION_EXTEND, \
 	 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
 
+#define SET_LOCKTAG_SMGR(locktag,relfilenode) \
+	((locktag).locktag_field1 = (relfilenode), \
+	 (locktag).locktag_field2 = 0, \
+	 (locktag).locktag_field3 = 0, \
+	 (locktag).locktag_field4 = 0, \
+	 (locktag).locktag_type = LOCKTAG_SMGR, \
+	 (locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
+
 #define SET_LOCKTAG_PAGE(locktag,dboid,reloid,blocknum) \
 	((locktag).locktag_field1 = (dboid), \
 	 (locktag).locktag_field2 = (reloid), \
diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h
index 69a624f..30e9567 100644
--- a/src/include/storage/smgr.h
+++ b/src/include/storage/smgr.h
@@ -55,6 +55,7 @@ typedef struct SMgrRelationData
 	BlockNumber smgr_targblock; /* current insertion target block */
 	BlockNumber smgr_fsm_nblocks;		/* last known size of fsm fork */
 	BlockNumber smgr_vm_nblocks;	/* last known size of vm fork */
+	BlockNumber smgr_ptrack_nblocks;	/* last known size of vm fork */
 
 	/* additional public fields may someday exist here */