Databases

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      Description — Working with Couchbase Lite Databases
      Related Content — Blobs | Documents | Indexing

      Create or Open Database

      You can create a new database and-or open an existing database, using the Database class. Just pass in a database name and optionally a DatabaseConfiguration — see Example 1.

      Things to watch for include:

      • If the named database does not exist in the specified, or default, location then a new one is created

      • The database is created in a default location unless you specify a directory for it — see: DatabaseConfiguration and DatabaseConfiguration.Directory()

        Best Practice is to always specify the path to the database explicitly.

        Typically, the default location for C#.Net is . a platform-dependant location:

        • .NET Core: Path.Combine(AppContext.BaseDirectory, "CouchbaseLite") (unless the app context is altered [e.g. by XUnit], this will be the same directory as the output binary)

        • UWP: Windows.Storage.ApplicationData.Current.LocalFolder.Path (Inside the installed app sandbox. Note that this sandbox gets deleted sometimes when debugging from inside Visual Studio when the app is shutdown)

        • Xamarin iOS: In a folder named CouchbaseLite inside of ApplicationSupportDirectory (this can be retrieved more easily from the simulator using the SimPholders utility)

        • Xamarin Android: Using the Context passed in the Activate() method, Context.FilesDir.AbsolutePath (database can be retrieved using adb)

      Example 1. Open or create a database
      var db = new Database("my-database");

      Close Database

      You are advised to incorporate the closing of all open databases into your application workflow.

      Closing a database is simple, just use Database.Close() — see: Example 2. This also closes [1] active replications, listeners and-or live queries connected to the database.

      Closing a database soon after starting a replication involving it can cause an exception as the asynchronous replicator (start) may not yet be connected.
      Safely Closing a Database pre 2.8
      Before closing, check that any attached listeners (query/replication/change) indicate they are at least at connected status before closing — see for example: Monitor Status.
      Example 2. Close a Database
      database.Close()

      Database Encryption

      This is an Enterprise Edition feature.

      Couchbase Lite on C#.Net includes the ability to encrypt Couchbase Lite databases. This allows mobile applications to secure the data at rest, when it is being stored on the device. The algorithm used to encrypt the database is 256-bit AES.

      Enabling

      To enable encryption, use DatabaseConfiguration.EncryptionKey() to set the encryption key of your choice. Provide this encryption key every time the database is opened — see Example 3.

      Example 3. Configure Database Encryption
      // Create a new, or open an existing database with encryption enabled
      var config = new DatabaseConfiguration
      {
          // Or, derive a key yourself and pass a byte array of the proper size
          EncryptionKey = new EncryptionKey("password")
      };
      
      using (var db = new Database("seekrit", config)) {
          // Change the encryption key (or add encryption if the DB is unencrypted)
          db.ChangeEncryptionKey(new EncryptionKey("betterpassw0rd"));
      
          // Remove encryption
          db.ChangeEncryptionKey(null);
      }

      Persisting

      Couchbase Lite does not persist the key. It is the application’s responsibility to manage the key and store it in a platform specific secure store such as Apple’s Keychain or Android’s Keystore.

      Opening

      An encrypted database can only be opened with the same language SDK that was used to encrypt it in the first place. So a database encrypted using the C#.Net SDK, and then exported, is readable only by the C#.Net SDK.

      Changing

      To change an existing encryption key, open the database using its existing encryption-key and use Database.ChangeEncryptionKey() to set the required new encryption-key value.

      Removing

      To remove encryption, open the database using its existing encryption-key and use Database.ChangeEncryptionKey() with a null value as the encryption key.

      Upgrading

      To upgrade an encrypted database see: Upgrade 1.x databases

      Finding a Database File

      Where a database goes by default depends on the platform it is running on. Here are the defaults for each platform:

      • .NET Core: Path.Combine(AppContext.BaseDirectory, "CouchbaseLite") (unless the app context is altered [e.g. by XUnit], this will be the same directory as the output binary)

      • UWP: Windows.Storage.ApplicationData.Current.LocalFolder.Path (Inside the installed app sandbox. Note that this sandbox gets deleted sometimes when debugging from inside Visual Studio when the app is shutdown)

      • Xamarin iOS: In a folder named CouchbaseLite inside of ApplicationSupportDirectory (this can be retrieved more easily from the simulator using the SimPholders utility)

      • Xamarin Android: Using the Context passed in the Activate() method, Context.FilesDir.AbsolutePath (database can be retrieved using adb)

      Database Maintenance

      From time to time it may be necessary to perform certain maintenance activities on your database, for example to compact the database file, removing unused documents and blobs no longer referenced by any documents.

      Couchbase Lite’s API provides the Database.PerformMaintenance() method. The available maintenance operations, including compact are as shown in the enum MaintenanceType to accomplish this.

      This is a resource intensive operation and is not performed automatically. It should be run on-demand using the API. If in doubt, consult Couchbase support.

      Command Line Tool

      cblite is a command-line tool for inspecting and querying Couchbase Lite databases.

      You can download and build it from the couchbaselabs GitHub repository. Note that the cblite tool is not supported by the Couchbase Support Policy.

      Troubleshooting

      You should use console logs as your first source of diagnostic information. If the information in the default logging level is insufficient you can focus it on database errors and generate more verbose messages — see: Example 4.

      For more on using Couchbase logs — see: Using Logs.

      Example 4. Increase Level of Database Log Messages
      Database.Log.Console.Domains = LogDomain.Database;

      1. Commencing with Release 2.8