Merge pull request #10249 from hpbieker/hpb-delete-from-prevent-rebuild-series

Prevent DELETE FROM to rebuild series files for shards where nothing is deleted

tsdb/engine/tsm1/engine.go

@@ -1616,7 +1616,14 @@ func (e *Engine) deleteSeriesRange(seriesKeys [][]byte, min, max int64) error {
 
 	// Have we deleted all values for the series? If so, we need to remove
 	// the series from the index.
-	if len(seriesKeys) > 0 {
+	hasDeleted := false;
+	for _, k := range seriesKeys {
+		if len(k) > 0 {
+			hasDeleted = true
+			break
+		}
+	}
+	if hasDeleted {
 		buf := make([]byte, 1024) // For use when accessing series file.
 		ids := tsdb.NewSeriesIDSet()
 		measurements := make(map[string]struct{}, 1)