list db mongo

Guri Bee

2 min read

·

19-10-2024

1

0

Share

Mastering MongoDB: A Comprehensive Guide to Listing Databases and Collections

MongoDB, a popular NoSQL database, offers flexible data storage and retrieval capabilities. Understanding how to list your databases and collections is crucial for efficient database management. This guide delves into the essential commands and concepts, drawing upon real-world examples and practical tips gleaned from the vibrant GitHub community.

Listing Databases: Your First Step in MongoDB Management

To start your journey, let's explore how to list all the databases available in your MongoDB instance.

1. Using the show dbs Command

The most straightforward method is to use the show dbs command in the MongoDB shell. This command returns a simple list of all available databases, including system databases like admin and local.

Example:

> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB
test    0.000GB

(Source: https://github.com/mongodb/mongo)

2. Exploring Databases with the db Command

You can also use the db command to get information about the currently active database. This can be helpful when you're working within a specific database and need to see its name.

Example:

> db
test

(Source: https://github.com/mongodb/mongo)

Diving Deeper: Listing Collections within a Database

Once you've identified the relevant database, you can delve into the collections within it.

1. Using the show collections Command

Similar to the show dbs command, you can use show collections to retrieve a list of collections within the active database.

Example:

> use myDatabase
switched to db myDatabase
> show collections
users
products
orders

(Source: https://github.com/mongodb/mongo)

2. Programmatic Listing with the listCollections Method

For more programmatic control, you can utilize the listCollections method available in MongoDB drivers. This method allows you to specify filters and options for retrieving collections.

Example (Node.js):

const MongoClient = require('mongodb').MongoClient;
const uri = "mongodb://localhost:27017";

async function listCollections() {
  const client = new MongoClient(uri);
  try {
    await client.connect();
    const db = client.db('myDatabase');
    const collections = await db.listCollections().toArray();
    console.log(collections);
  } catch (err) {
    console.error(err);
  } finally {
    await client.close();
  }
}

listCollections();

(Source: https://github.com/mongodb/node-mongodb-native)

Beyond the Basics: Filtering and Accessing Information

To enhance your database management, you can utilize advanced techniques:

• Filtering with Regular Expressions: You can use the show collections command with regular expressions to filter collections based on their names.
• Accessing Metadata: You can use commands like db.collectionName.stats() to retrieve information about a specific collection's size, document count, and other statistics.

Conclusion

This guide has armed you with the essential commands and techniques for listing databases and collections in MongoDB. Whether you're using the interactive shell or programming languages, understanding these methods will empower you to efficiently manage your data and unlock the full potential of MongoDB. Remember, as you progress, explore the vast resources and vibrant community on GitHub to continuously expand your MongoDB expertise.