Removed index page pinning for HNSW

src/ivfflat.h

@@ -40,9 +40,6 @@
 #define IVFFLAT_METAPAGE_BLKNO	0
 #define IVFFLAT_HEAD_BLKNO		1	/* first list page */
 
-/* Must correspond to page numbers since page lock is used */
-#define IVFFLAT_SCAN_LOCK		0
-
 /* IVFFlat parameters */
 #define IVFFLAT_DEFAULT_LISTS	100
 #define IVFFLAT_MIN_LISTS		1
@@ -249,7 +246,6 @@ typedef struct IvfflatScanOpaqueData
 	int			probes;
 	int			dimensions;
 	bool		first;
-	bool		hasLock;
 	Buffer		buf;
 	ItemPointerData heaptid;
 

src/ivfscan.c

@@ -9,7 +9,6 @@
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "storage/bufmgr.h"
-#include "storage/lmgr.h"
 
 /*
  * Compare list distances
@@ -264,7 +263,6 @@ ivfflatbeginscan(Relation index, int nkeys, int norderbys)
 	so = (IvfflatScanOpaque) palloc(offsetof(IvfflatScanOpaqueData, lists) + probes * sizeof(IvfflatScanList));
 	so->buf = InvalidBuffer;
 	so->first = true;
-	so->hasLock = false;
 	ItemPointerSetInvalid(&so->heaptid);
 	so->probes = probes;
 	so->dimensions = dimensions;
@@ -349,13 +347,6 @@ ivfflatgettuple(IndexScanDesc scan, ScanDirection dir)
 		if (scan->orderByData == NULL)
 			elog(ERROR, "cannot scan ivfflat index without order");
 
-		/* Get a shared lock for non-MVCC snapshots */
-		if (!so->hasLock && !IsMVCCSnapshot(scan->xs_snapshot))
-		{
-			so->hasLock = true;
-			LockPage(scan->indexRelation, IVFFLAT_SCAN_LOCK, ShareLock);
-		}
-
 		if (scan->orderByData->sk_flags & SK_ISNULL)
 			value = PointerGetDatum(InitVector(so->dimensions));
 		else
@@ -431,10 +422,6 @@ ivfflatendscan(IndexScanDesc scan)
 	if (BufferIsValid(so->buf))
 		ReleaseBuffer(so->buf);
 
-	/* Release lock */
-	if (so->hasLock)
-		UnlockPage(scan->indexRelation, IVFFLAT_SCAN_LOCK, ShareLock);
-
 	pairingheap_free(so->listQueue);
 	tuplesort_end(so->sortstate);
 

src/ivfvacuum.c

@@ -3,7 +3,6 @@
 #include "commands/vacuum.h"
 #include "ivfflat.h"
 #include "storage/bufmgr.h"
-#include "storage/lmgr.h"
 
 /*
  * Bulk delete tuples from the index
@@ -66,10 +65,14 @@ ivfflatbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
 
 				vacuum_delay_point();
 
-				/* Ensure no in-flight index scans for non-MVCC snapshots */
-				LockPage(index, IVFFLAT_SCAN_LOCK, ExclusiveLock);
-
 				buf = ReadBufferExtended(index, MAIN_FORKNUM, searchPage, RBM_NORMAL, bas);
+
+				/*
+				 * ambulkdelete cannot delete entries from pages that are
+				 * pinned by other backends
+				 *
+				 * https://www.postgresql.org/docs/current/index-locking.html
+				 */
 				LockBufferForCleanup(buf);
 
 				state = GenericXLogStart(index);
@@ -111,8 +114,6 @@ ivfflatbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
 					GenericXLogAbort(state);
 
 				UnlockReleaseBuffer(buf);
-
-				UnlockPage(index, IVFFLAT_SCAN_LOCK, ExclusiveLock);
 			}
 
 			/*