private FilterDefinition <BsonDocument> CreateQueryForRelevantDocuments( Type type) { var currentVersion = _versionService.GetCurrentOrLatestMigrationVersion(type); var existFilter = Builders <BsonDocument> .Filter.Exists(_versionService.GetVersionFieldName(), false); var notEqualFilter = Builders <BsonDocument> .Filter.Ne( _versionService.GetVersionFieldName(), currentVersion); return(Builders <BsonDocument> .Filter.Or(existFilter, notEqualFilter)); }