.

go/zodb/storage/fs1/filestorage.go

@@ -599,6 +599,7 @@ func (dh *DataHeader) loadPrevRev(r io.ReaderAt) error {
 // LoadBackRef reads data for the data record and decodes it as backpointer reference.
 // prerequisite: dh loaded and .LenData == 0 (data record with back-pointer)
 // XXX return backPos=-1 if err?
+// XXX unused?
 func (dh *DataHeader) LoadBackRef(r io.ReaderAt) (backPos int64, err error) {
 	if dh.DataLen != 0 {
 		bug(dh, "LoadBack() on non-backpointer data header")

go/zodb/storage/fs1/fs1tools/dump.go

@@ -129,6 +129,10 @@ func Dump(w io.Writer, path string, dir fs1.IterDir, d Dumper) (err error) {
 //	https://github.com/zopefoundation/ZODB/commit/ddcb46a2
 type DumperFsDump struct {
 	ntxn  int // current transaction record #
+
+	// for loading data
+	dhLoading fs1.DataHeader
+	data      []byte
 }
 
 func (d *DumperFsDump) DumperName() string {
@@ -164,19 +168,21 @@ func (d *DumperFsDump) DumpTxn(buf *xfmt.Buffer, it *fs1.Iter) error {
 		buf .S(fmt.Sprintf("%05d", j))	// XXX -> .D_f("05", j)
 		buf .S(" oid=") .V(dh.Oid)
 
-		if dh.DataLen == 0 {
-			buf .S(" class=undo or abort of object creation")
-
-			backPos, err := dh.LoadBackRef(it.R)
-			if err != nil {
-				// XXX
-			}
+		// load actual data
+		d.dhLoading = *dh
+		data := d.data
+		err = d.dhLoading.LoadData(it.R, &data)
+		if err != nil {
+			return err
+		}
+		// if memory was reallocated - use it next time
+		if cap(data) > cap(d.data) {
+			d.data = data
+		}
 
-			if backPos != 0 {
-				buf .S(" bp=") .X016(uint64(backPos))
-			}
+		if data == nil {
+			buf .S(" class=undo or abort of object creation")
 		} else {
-			// XXX Datah.LoadData()
 			//modname, classname = zodb.GetPickleMetadata(...)	// XXX
 			//fullclass = "%s.%s" % (modname, classname)
 			fullclass := "AAA.BBB"	// FIXME stub
@@ -185,6 +191,11 @@ func (d *DumperFsDump) DumpTxn(buf *xfmt.Buffer, it *fs1.Iter) error {
 			buf .S(" class=") .S(fullclass)
 		}
 
+		if dh.DataLen == 0 && data != nil {
+			// it was backpointer - print tid of transaction it points to
+			buf .S(" bp=") .V(d.dhLoading.Tid)
+		}
+
 		buf .S("\n")
 	}
 

go/zodb/storage/fs1/fs1tools/reindex.go

@@ -60,7 +60,7 @@ func VerifyIndexFor(path string) error {
 
 // ----------------------------------------
 
-const reindexSummary = "dump last few transactions of a database"
+const reindexSummary = "XXX"	// XXX
 
 func reindexUsage(w io.Writer) {
 	fmt.Fprintf(w,