Bugfix on merging i64 fast fields

src/core/segment_reader.rs

@@ -25,6 +25,8 @@ use schema::FieldType;
 use postings::FreqHandler;
 use schema::TextIndexingOptions;
 
+
+
 /// Entry point to access all of the datastructures of the `Segment`
 ///
 /// - term dictionary
@@ -74,6 +76,11 @@ impl SegmentReader {
         self.delete_bitset.len() as DocId
     }
 
+    #[doc(hidden)]
+    pub fn fast_fields_reader(&self) -> &FastFieldsReader {
+        &*self.fast_fields_reader
+    }
+
     /// Accessor to a segment's fast field reader given a field.
     ///
     /// Returns the u64 fast value reader if the field

src/indexer/merger.rs

@@ -77,8 +77,8 @@ fn extract_fieldnorm_reader(segment_reader: &SegmentReader, field: Field) -> Opt
 
 fn extract_fast_field_reader(segment_reader: &SegmentReader, field: Field) -> Option<U64FastFieldReader> {
     segment_reader
-        .get_fast_field_reader(field)
-        .ok()
+        .fast_fields_reader()
+        .open_reader(field)
 }
 
 impl IndexMerger {