Added free space map for HNSW [skip ci]

src/hnsw.h

@@ -485,6 +485,7 @@ void		HnswSetElementTuple(char *base, HnswElementTuple etup, HnswElement element
 void		HnswUpdateConnection(char *base, HnswNeighborArray * neighbors, HnswElement newElement, float distance, int lm, int *updateIdx, Relation index, HnswSupport * support);
 bool		HnswLoadNeighborTids(HnswElement element, ItemPointerData *indextids, Relation index, int m, int lm, int lc);
 void		HnswInitLockTranche(void);
+void		HnswRecordPageWithFreeSpace(Relation index, BlockNumber blkno, Page page);
 void		HnswCheckDim(int expected, const HnswTypeInfo * typeInfo, Oid collation, Datum value);
 const		HnswTypeInfo *HnswGetTypeInfo(Relation index);
 PGDLLEXPORT void HnswParallelBuildMain(dsm_segment *seg, shm_toc *toc);

src/hnswinsert.c

@@ -5,6 +5,7 @@
 #include "hnsw.h"
 #include "nodes/execnodes.h"
 #include "storage/bufmgr.h"
+#include "storage/freespace.h"
 #include "storage/lmgr.h"
 #include "storage/lwlock.h"
 #include "utils/datum.h"
@@ -153,7 +154,7 @@ AddElementOnDisk(Relation index, HnswElement e, int m, BlockNumber insertPage, B
 	Size		maxSize;
 	Size		minCombinedSize;
 	HnswElementTuple etup;
-	BlockNumber currentPage = insertPage;
+	BlockNumber currentPage = InvalidBlockNumber;
 	HnswNeighborTuple ntup;
 	Buffer		nbuf;
 	Page		npage;
@@ -162,6 +163,8 @@ AddElementOnDisk(Relation index, HnswElement e, int m, BlockNumber insertPage, B
 	BlockNumber newInsertPage = InvalidBlockNumber;
 	uint8		tupleVersion;
 	char	   *base = NULL;
+	bool		tryFsm = !building;
+	int			fsmTries = 0;
 
 	/* Calculate sizes */
 	etupSize = HNSW_ELEMENT_TUPLE_SIZE(VARSIZE_ANY(HnswPtrAccess(base, e->value)));
@@ -181,6 +184,20 @@ AddElementOnDisk(Relation index, HnswElement e, int m, BlockNumber insertPage, B
 	/* Find a page (or two if needed) to insert the tuples */
 	for (;;)
 	{
+		bool		fsmPage = false;
+
+		/* Try free space map */
+		if (tryFsm)
+		{
+			/* TODO do not retry same page */
+			currentPage = GetPageWithFreeSpace(index, etupSize);
+			fsmPage = BlockNumberIsValid(currentPage);
+			tryFsm = ++fsmTries < 3 && BlockNumberIsValid(currentPage);
+		}
+
+		if (!BlockNumberIsValid(currentPage))
+			currentPage = insertPage;
+
 		buf = ReadBuffer(index, currentPage);
 		LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
 
@@ -196,7 +213,7 @@ AddElementOnDisk(Relation index, HnswElement e, int m, BlockNumber insertPage, B
 		}
 
 		/* Keep track of first page where element at level 0 can fit */
-		if (!BlockNumberIsValid(newInsertPage) && PageGetFreeSpace(page) >= minCombinedSize)
+		if (!BlockNumberIsValid(newInsertPage) && PageGetFreeSpace(page) >= minCombinedSize && !fsmPage)
 			newInsertPage = currentPage;
 
 		/* First, try the fastest path */
@@ -328,6 +345,10 @@ AddElementOnDisk(Relation index, HnswElement e, int m, BlockNumber insertPage, B
 			elog(ERROR, "failed to add index item to \"%s\"", RelationGetRelationName(index));
 	}
 
+	/* Update free space map */
+	if (!building)
+		HnswRecordPageWithFreeSpace(index, e->blkno, page);
+
 	/* Commit */
 	if (building)
 	{

src/hnswutils.c

@@ -12,6 +12,7 @@
 #include "port/atomics.h"
 #include "sparsevec.h"
 #include "storage/bufmgr.h"
+#include "storage/freespace.h"
 #include "utils/datum.h"
 #include "utils/fmgrprotos.h"
 #include "utils/memdebug.h"
@@ -1359,6 +1360,39 @@ HnswFindElementNeighbors(char *base, HnswElement element, HnswElement entryPoint
 	}
 }
 
+/*
+ * Record free space
+ */
+void
+HnswRecordPageWithFreeSpace(Relation index, BlockNumber blkno, Page page)
+{
+	Size		freeSpace = 0;
+	OffsetNumber maxoffno = PageGetMaxOffsetNumber(page);
+
+	for (OffsetNumber offno = FirstOffsetNumber; offno <= maxoffno; offno = OffsetNumberNext(offno))
+	{
+		ItemId		itemid = PageGetItemId(page, offno);
+		HnswElementTuple etup = (HnswElementTuple) PageGetItem(page, itemid);
+		Size		itemsize;
+
+		/* Skip neighbor tuples */
+		if (!HnswIsElementTuple(etup))
+			continue;
+
+		/* Skip live tuples */
+		if (!etup->deleted)
+			continue;
+
+		/* Keep track of largest element tuple that will fit */
+		itemsize = ItemIdGetLength(itemid);
+		freeSpace = Max(freeSpace, itemsize);
+	}
+
+	freeSpace += PageGetExactFreeSpace(page);
+
+	RecordPageWithFreeSpace(index, blkno, freeSpace);
+}
+
 /*
  * Check dimensions match index
  */

src/hnswvacuum.c

@@ -6,6 +6,7 @@
 #include "hnsw.h"
 #include "nodes/pg_list.h"
 #include "storage/bufmgr.h"
+#include "storage/freespace.h"
 #include "storage/lmgr.h"
 #include "utils/memutils.h"
 #include "utils/rel.h"
@@ -709,21 +710,24 @@ MarkDeleted(HnswVacuumState * vacuumstate)
 			if (nbuf != buf)
 				UnlockReleaseBuffer(nbuf);
 
-			/* Set to first free page */
-			if (!BlockNumberIsValid(insertPage))
-				insertPage = blkno;
-
 			/* Prepare new xlog */
 			state = GenericXLogStart(index);
 			page = GenericXLogRegisterBuffer(state, buf, 0);
 		}
 
+		HnswRecordPageWithFreeSpace(index, blkno, page);
+
+		/* Set to last page */
+		insertPage = blkno;
+
 		blkno = HnswPageGetOpaque(page)->nextblkno;
 
 		GenericXLogAbort(state);
 		UnlockReleaseBuffer(buf);
 	}
 
+	FreeSpaceMapVacuum(index);
+
 	/* Update insert page last, after everything has been marked as deleted */
 	HnswUpdateMetaPage(index, 0, NULL, insertPage, MAIN_FORKNUM, false);
 }