diff --git a/mobile/lib/db/common/base.dart b/mobile/lib/db/common/base.dart
index 9266e67033..6d01cf4ff4 100644
--- a/mobile/lib/db/common/base.dart
+++ b/mobile/lib/db/common/base.dart
@@ -4,7 +4,7 @@ import "package:sqlite_async/sqlite_async.dart";
 mixin SqlDbBase {
   static const _params = {};
 
-  static String getParams(int count) {
+  String getParams(int count) {
     if (!_params.containsKey(count)) {
       final params = List.generate(count, (_) => "?").join(", ");
       _params[count] = params;
diff --git a/mobile/lib/db/local/db.dart b/mobile/lib/db/local/db.dart
index 465e9687fd..91d0737366 100644
--- a/mobile/lib/db/local/db.dart
+++ b/mobile/lib/db/local/db.dart
@@ -5,12 +5,13 @@ import "package:flutter/foundation.dart";
 import "package:path/path.dart";
 import "package:path_provider/path_provider.dart";
 import "package:photo_manager/photo_manager.dart";
+import "package:photos/db/common/base.dart";
 import "package:photos/db/local/mappers.dart";
 import "package:photos/db/local/schema.dart";
 import "package:photos/log/devlog.dart";
 import "package:sqlite_async/sqlite_async.dart";
 
-class LocalDB {
+class LocalDB with SqlDbBase {
   static const _databaseName = "local_2.db";
   static const _batchInsertMaxCount = 1000;
   static const _smallTableBatchInsertMaxCount = 5000;
@@ -23,7 +24,7 @@ class LocalDB {
     final String path = join(documentsDirectory.path, _databaseName);
 
     final database = SqliteDatabase(path: path);
-    await LocalDBMigration.migrate(database);
+    await migrate(database, LocalDBMigration.migrationScripts);
     _sqliteDB = database;
     devLog("LocalDB init complete $path");
   }
@@ -35,7 +36,7 @@ class LocalDB {
       final List<List<Object?>> values =
           slice.map((e) => LocalDBMappers.assetsRow(e)).toList();
       await _sqliteDB.executeBatch(
-        'INSERT OR REPLACE INTO assets ($assetColumns) values(${placeHolderMap[15]})',
+        'INSERT OR REPLACE INTO assets ($assetColumns) values(${getParams(15)})',
         values,
       );
     });
@@ -52,7 +53,7 @@ class LocalDB {
       final List<List<Object?>> values =
           slice.map((e) => LocalDBMappers.devicePathRow(e)).toList();
       await _sqliteDB.executeBatch(
-        'INSERT OR REPLACE INTO device_path ($devicePathColumns) values(${placeHolderMap[5]})',
+        'INSERT OR REPLACE INTO device_path ($devicePathColumns) values(${getParams(5)})',
         values,
       );
     });
diff --git a/mobile/lib/db/local/schema.dart b/mobile/lib/db/local/schema.dart
index 85cc353253..4244dbbaad 100644
--- a/mobile/lib/db/local/schema.dart
+++ b/mobile/lib/db/local/schema.dart
@@ -6,23 +6,6 @@ const assetColumns =
 
 const devicePathColumns =
     "path_id, name, album_type, ios_album_type, ios_album_subtype";
-const placeHolderMap = {
-  1: "?",
-  2: "?,?",
-  3: "?,?,?",
-  4: "?,?,?,?",
-  5: "?,?,?,?,?",
-  6: "?,?,?,?,?,?",
-  7: "?,?,?,?,?,?,?",
-  8: "?,?,?,?,?,?,?,?",
-  9: "?,?,?,?,?,?,?,?,?",
-  10: "?,?,?,?,?,?,?,?,?,?",
-  11: "?,?,?,?,?,?,?,?,?,?,?",
-  12: "?,?,?,?,?,?,?,?,?,?,?,?",
-  13: "?,?,?,?,?,?,?,?,?,?,?,?,?",
-  14: "?,?,?,?,?,?,?,?,?,?,?,?,?,?",
-  15: "?,?,?,?,?,?,?,?,?,?,?,?,?,?,?",
-};
 
 class LocalDBMigration {
   static const migrationScripts = [
diff --git a/mobile/lib/services/local/import/device_assets.service.dart b/mobile/lib/services/local/import/device_assets.service.dart
index df5db7fc76..b65b282f73 100644
--- a/mobile/lib/services/local/import/device_assets.service.dart
+++ b/mobile/lib/services/local/import/device_assets.service.dart
@@ -11,6 +11,9 @@ import "package:photos/services/local/import/model.dart";
 
 class DeviceAssetsService {
   final _logger = Logger("DeviceAssetsService");
+  // The ignoreSizeConstraint is used to ignore the size constraint, otherwise
+  // photo manager will only give assets that meet it's default constraint where
+  // only assets with w/h in [0,100000] dim will be returned
   static const ignoreSizeConstraint = SizeConstraint(ignoreSize: true);
   static const assetFetchPageSize = 2000;
 
@@ -62,6 +65,9 @@ class DeviceAssetsService {
     return r;
   }
 
+  // _getAssetPaths will return AssetEntityPath and assets that will meet the
+  // specified filter conditions. If fromTimeInMs and toTimeInMs are provided,
+  // we will only get those assets that were updated in the specified time.
   Future<List<DevicePathAssets>> _getDevicePathAssets({
     int? fromTimeInMs,
     int? toTimeInMs,
@@ -95,6 +101,7 @@ class DeviceAssetsService {
     final OrderOption? orderOption,
   }) async {
     final filterOptionGroup = FilterOptionGroup();
+
     filterOptionGroup.setOption(
       AssetType.image,
       FilterOption(needTitle: needsTitle, sizeConstraint: ignoreSizeConstraint),
@@ -113,6 +120,10 @@ class DeviceAssetsService {
         max: DateTime.fromMillisecondsSinceEpoch(updateToTimeInMs),
       );
     } else {
+      // During full diff, ignore the default creation time filter otherwise
+      // photo manager will only give assets with creation time between [0, now()]
+      // utc. This will cause the app to miss out on assets that have creation_time
+      // outside this time window.
       filterOptionGroup.createTimeCond =
           DateTimeCond.def().copyWith(ignore: true);
     }