Databases

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

Database Concepts

Databases created on Couchbase Lite can share the same hierarchical structure as Capella databases. This makes it easier to sync data between mobile applications and applications built using Capella.

Figure 1. Couchbase Lite Database Hierarchy

Although the terminology is different, the structure can be mapped to relational database terms:

Table 1. Relational Database → Couchbase

Relational database	Couchbase
Database	Database
Schema	Scope
Table	Collection

This structure gives you plenty of choices when it comes to partitioning your data. The most basic structure is to use the single default scope with a single default collection; or you could opt for a structure that allow you to split your collections into logical scopes.

Figure 2. Couchbase Lite Examples

Storing local configuration

You may not need to sync all the data related to a particular application. You can set up a scope that syncs data, and a second scope that doesn’t. One reason for doing this is to store local configuration data (such as the preferred screen orientation or keyboard layout). Since this information only relates to a particular device, there is no need to sync it:

• local data scope — Contains information pertaining to the device.
• syncing data scope — Contains information pertaining to the user, which can be synced back to the cloud for use on the web or another device.

Managing Couchbase Lite Databases in Ionic

Initializing the Environment

In an Ionic application using Couchbase Lite, begin by initializing the Capacitor Engine. Subsequently, employ a design pattern such as Context/Provider or Service Locator to maintain and access your database instances throughout the application lifecycle.

Example: Initializing Capacitor Engine and Database Context

import { CapacitorEngine } from 'cbl-ionic';

const engine = new CapacitorEngine(); // Initialize once, early in your app

This configuration ensures seamless interaction between your Ionic app and the underlying native database functionalities, facilitating effective database management. This only needs to be done once in your application and must be done before any other Couchbase Lite operations are performed.

Create or Open a Database

To create or open a database, use the Database class from the cbl-ionic package, specifying the database name and optionally, a DatabaseConfiguration for custom settings like the database directory or encryption.

Example 1. Creating/Opening a Database

import { Database, DatabaseConfiguration } from 'cbl-ionic'; //import the package

const config = new DatabaseConfiguration();
config.setDirectory('path/to/database'); // Optional
const myDatabase = new Database('myDatabaseName', config);
await myDatabase.open();

Closing a Database

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

Example 2. Closing a Database

await myDatabase.close();

Deleting a Database

The delete method is used to delete a database.

 await database.deleteDatabase();

Alternatively, you can delete a database by calling the delete method on the Database class.

Database.deleteDatabase('myDatabaseName', 'path/to/database');

Database Encryption

Couchbase Lite Enterprise Edition includes the ability to encrypt Couchbase Lite databases. This allows mobile applications to secure 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 database encryption in Ionic, use the DatabaseConfiguration class to set an encryption key before opening or creating a database. This encryption key must be provided every time the database is accessed.

Example3. Configure Database Encryption

const dbName = 'my_secure_db';
const encryptionKey = 'my_secret_key';

const config = new DatabaseConfiguration();
config.setEncryptionKey(encryptionKey);

const db = new Database(dbName, config);

await db.open();

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 Apples's Keystore or Android’s Keystore.

Opening

An encrypted database can only be opened with the same language package that was used to encrypt it in the first place. So a database encrypted using the Ionic package on iOS, and then exported, is readable only by the iOS SDK since cbl-ionic is a wrapper around the native SDKs.

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.

const dbName = 'my_secure_db';
const config = new DatabaseConfiguration();
const db = new Database(dbName, config);
await db.open();
await db.performMaintenance(MaintenanceType.compact);

This is a resource intensive operation and is not performed automatically. It should be run on-demand using the API. A full listing of the available maintenance operations is shown below:

• MaintenanceType.compact: Compact the database file and delete unused attachments.
• MaintenanceType.reindex: (Volatile API) Rebuild the entire database’s indexes.
• MaintenanceType.integrityCheck: (Volatile API) Check for the database’s corruption. If found, an error will be returned.
• MaintenanceType.optimize: Quickly updates database statistics that may help optimize queries that have been run by this Database since it was opened
• MaintenanceType.fullOptimize: Fully scans all indexes to gather database statistics that help optimize queries.

For questions or issues, please visit the Couchbase Forums where you can ask for help and discuss with the community.

Deprecated API

With the introduction of Scopes and Collections, several Database APIs in the Ionic package are now deprecated. These features will be removed in a future release, and developers are encouraged to use the Scopes/Collections APIs instead for these operations.

Document APIs

• deleteDocument
• getCount
• getDocument
• purgeDocument
• save

Index APIs

• createIndex
• getIndexes
• deleteIndex

For developers not working with custom Scopes/Collections, you can use the _default (default) scope and collection to achieve the same functionality with the new Scopes/Collections APIs.

Couchbase Lite for VSCode

Couchbase Lite for VSCode is a Visual Studio Code extension that provides a user interface for inspecting and querying Couchbase Lite databases. You can find more information about this extension from it's GitHub repository.

Couchbase Lite for JetBrains

Couchbase Lite for JetBrains is a JetBrains IDE plugin that provides a user interface for inspecting and querying Couchbase Lite databases. You can find more information about this plugin from its GitHub repository.

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.

try {
  await db.setLogLevel(LogDomain.DATABASE, LogLevel.VERBOSE);
  console.log('Database log level set to VERBOSE.');
} catch (error) {
  console.error('Setting log level failed:', error);
}