try to perform backups without killing the server

services/database/backuptool/backuptool.go

@@ -84,12 +84,18 @@ func scanner(db *db_client.DatabaseRpcClient, bucketCh chan string, outCh chan R
 	defer session.Close()
 
 	for bucket := range bucketCh {
-		iter, err := session.Scan(bucket, "", "\xff", -1)
+		// Call Scan() in batches, to avoid overloading the server.
+		batchSize := 1000
+		startKey, endKey := "", "\xff"
+		for startKey < endKey {
+			iter, err := session.Scan(bucket, startKey, endKey, batchSize)
 			if err != nil {
 				log.Printf("Scan error for bucket %s: %s", bucket, err)
-			continue
+				break
 			}
 
+			// Iterate over the results and send them to outCh.
+			n := 0
 			for {
 				var data []byte
 				key, err := iter.Next(&data)
@@ -102,6 +108,16 @@ func scanner(db *db_client.DatabaseRpcClient, bucketCh chan string, outCh chan R
 					Key:    key,
 					Data:   data,
 				}
+				n++
+				startKey = key
+			}
+			// An empty result means we've reached the end
+			// of the scan.
+			if n == 0 {
+				break
+			}
+			// Start the next scan from the next key.
+			startKey = db_client.IncrementKey(startKey)
 		}
 	}
 }