1 files changed, 4 insertions, 0 deletions
diff --git a/dataset/file.go b/dataset/file.go
index 081fbdf..242172e 100644
--- a/dataset/file.go
+++ b/dataset/file.go
@@ -37,6 +37,10 @@ func NewFileReader(name, pattern string) (*FileReader, error) {
 	return f, nil
 }
 
+func (f *FileReader) Num() (int, error) {
+	return len(f.shards), nil
+}
+
 func (f *FileReader) Err() error {
 	return f.err
 }