# JournalId.IsPrefixOf(JournalId)

[Type overview](/orleans/docs/api/csharp/microsoft.orleans.journaling/orleans.journaling.journalid/) | [Methods](/orleans/docs/api/csharp/microsoft.orleans.journaling/orleans.journaling.journalid/methods/)

[Source](https://github.com/dotnet/orleans/blob/e4e752cedecc2976811db49802c7a999b1f1c704/src/Orleans.Journaling/JournalId.cs#L103-L114)

```csharp
public bool IsPrefixOf(JournalId journalId)
```

Determines whether this id is a prefix of `journalId`.

### Parameters

- `journalId` (`JournalId`): The journal id to test.

### Returns

`true` if this id is the default value, equals `journalId`, or identifies an ancestor segment.