PouchDB Interview Questions and Answers

This section covers frequently asked PouchDB interview questions, focusing on its core features, data management, and synchronization capabilities.

What is PouchDB?

PouchDB is a JavaScript library providing a client-side database API that mimics the functionality of CouchDB. It allows building applications that work offline and synchronize data with a CouchDB server when online. It uses WebSQL and IndexedDB as its underlying storage mechanisms.

More information on PouchDB

How PouchDB Works

PouchDB stores data locally in the browser (using WebSQL or IndexedDB, depending on browser support). When online, it synchronizes this data with a remote CouchDB or compatible database server. This provides seamless offline/online functionality.

Key Features of PouchDB

  • Cross-browser compatibility
  • Lightweight
  • Easy to learn
  • Open-source

Browsers Supporting PouchDB

PouchDB is supported by major browsers (Chrome, Firefox, Safari, Edge, Opera) and mobile platforms (Android, iOS, Windows Phone).

Advantages of PouchDB

  • High performance (local storage).
  • Offline/online synchronization.

Installing PouchDB

[Explain the process of installing PouchDB using Node.js and npm. This would generally involve running the command `npm install pouchdb`.]

More information on PouchDB installation

Creating a PouchDB Database

Syntax

let db = new PouchDB('mydatabase');

More information on creating databases

db.info() Method

The db.info() method retrieves information about a database (name, update sequence, etc.).

Syntax

db.info(function(err, info) {
    // Handle error or display info
});

More information on db.info()

Deleting a PouchDB Database

Syntax

db.destroy(function(err, res) {
    // Handle error or confirm deletion
});

More information on deleting databases

Deleting a Remote CouchDB Database

Specify the remote CouchDB URL in the PouchDB constructor to delete a remote database.

db.put() Method

The db.put() method adds a new document to the database. It requires the document data and accepts an optional callback.

More information on db.put()

Fetching Documents

The db.get() method retrieves a specific document by its ID.

More information on fetching documents

Updating Documents

Use db.put(). Include the _rev value (revision ID) from the existing document to ensure you're updating the correct version.

More information on updating documents

Deleting Documents

The db.remove() method deletes a document. You need the document ID and revision ID (_rev).

More information on deleting documents

Batches in PouchDB

A batch is an array of documents. db.bulkDocs() is used for bulk document operations.

More information on batches

Fetching Batches

Use the db.allDocs() method to retrieve multiple documents.

More information on fetching batches

Updating Batches

Use db.bulkDocs() to update multiple documents simultaneously. You'll need the _id and _rev values.

More information on updating batches

Deleting Batches

Use db.bulkDocs() to delete multiple documents simultaneously.

More information on deleting batches

Attachments in PouchDB

Attachments are binary files (images, etc.) associated with documents.

Adding Attachments

Use db.putAttachment() to add an attachment to a document. You'll need the document ID, attachment ID, MIME type, and the attachment data.

More information on adding attachments

Retrieving Attachments

Use db.getAttachment() to retrieve an attachment. It returns a Blob or Buffer object.

More information on retrieving attachments

Deleting Attachments

Use db.removeAttachment() to delete an attachment. You'll need the document ID, attachment ID, and revision (_rev) of the document.

More information on deleting attachments