Add additional logs to show progress of reindexing operation. (#3746)

posting/index.go

@@ -492,16 +492,17 @@ type rebuilder struct {
 }
 
 func (r *rebuilder) Run(ctx context.Context) error {
-	glog.V(1).Infof("Rebuild: Starting process. StartTs=%d. Prefix=\n%s\n",
-		r.startTs, hex.Dump(r.prefix))
+	glog.V(1).Infof(
+		"Rebuilding index for predicate %s: Starting process. StartTs=%d. Prefix=\n%s\n",
+		r.attr, r.startTs, hex.Dump(r.prefix))
 
 	// We create one txn for all the mutations to be housed in. We also create a
 	// localized posting list cache, to avoid stressing or mixing up with the
 	// global lcache (the LRU cache).
 	txn := NewTxn(r.startTs)
 
 	stream := pstore.NewStreamAt(r.startTs)
-	stream.LogPrefix = fmt.Sprintf("Rebuilding index for predicate %s", r.attr)
+	stream.LogPrefix = fmt.Sprintf("Rebuilding index for predicate %s:", r.attr)
 	stream.Prefix = r.prefix
 	stream.KeyToList = func(key []byte, itr *badger.Iterator) (*bpb.KVList, error) {
 		// We should return quickly if the context is no longer valid.
@@ -533,16 +534,20 @@ func (r *rebuilder) Run(ctx context.Context) error {
 		// so this function doesn't have any work to do.
 		return nil
 	}
+
 	if err := stream.Orchestrate(ctx); err != nil {
 		return err
 	}
-	glog.V(1).Infof("Rebuild: Iteration done. Now committing at ts=%d\n", r.startTs)
+	glog.V(1).Infof("Rebuilding index for predicate %s: Iteration done. Now committing at ts=%d\n",
+		r.attr, r.startTs)
 
 	// Convert data into deltas.
 	txn.Update()
 
 	// Now we write all the created posting lists to disk.
 	writer := NewTxnWriter(pstore)
+	counter := 0
+	numDeltas := len(txn.cache.deltas)
 	for key, delta := range txn.cache.deltas {
 		if len(delta) == 0 {
 			continue
@@ -553,6 +558,12 @@ func (r *rebuilder) Run(ctx context.Context) error {
 		if err := writer.SetAt([]byte(key), delta, BitDeltaPosting, r.startTs); err != nil {
 			return err
 		}
+
+		counter++
+		if counter%1e5 == 0 {
+			glog.V(1).Infof("Rebuilding index for predicate %s: wrote %d of %d deltas to disk.\n",
+				r.attr, counter, numDeltas)
+		}
 	}
 	glog.V(1).Infoln("Rebuild: Flushing all writes.")
 	return writer.Flush()