fix: [2.5] inverted index null offset file not compacted (#46775) (#46868)

relate: #46774
pr: #46775

Signed-off-by: aoiasd <zhicheng.yue@zilliz.com>

Author: aoiasd

internal/core/src/index/InvertedIndexTantivy.cpp

@@ -215,7 +215,13 @@ InvertedIndexTantivy<T>::LoadIndexMetas(
         if (file_name.find(INDEX_NULL_OFFSET_FILE_NAME) != std::string::npos) {
             null_offset_files.push_back(file);
         }
+
+        // add slice meta file for null offset file compact
+        if (file_name == INDEX_FILE_SLICE_META) {
+            null_offset_files.push_back(file);
+        }
     }
+
     if (null_offset_files.size() > 0) {
         // null offset file is sliced
         auto index_datas =
@@ -243,6 +249,10 @@ InvertedIndexTantivy<T>::RetainTantivyIndexFiles(
                 auto file_name =
                     boost::filesystem::path(file).filename().string();
                 return file_name == "index_type" ||
+                       // Slice meta is only used to compact null_offset files and non_exist_offset files.
+                       // It can be removed after compaction is complete.
+                       // Other index files are compacted by slice index instead of meta.
+                       file_name == INDEX_FILE_SLICE_META ||
                        file_name.find(INDEX_NULL_OFFSET_FILE_NAME) !=
                            std::string::npos;
             }),

internal/core/src/index/JsonInvertedIndex.cpp

@@ -234,6 +234,10 @@ JsonInvertedIndex<T>::LoadIndexMetas(
             std::string::npos) {
             non_exist_offset_files.push_back(file);
         }
+        // add slice meta file for null offset file compact
+        if (file_name == INDEX_FILE_SLICE_META) {
+            non_exist_offset_files.push_back(file);
+        }
     }
     if (non_exist_offset_files.size() > 0) {
         // null offset file is sliced