Automatic Deletion of Documents in MongoDB

Using TTL Indexes for Expiring Data

MongoDB provides a built-in mechanism to automatically delete documents after a certain period using TTL (Time-To-Live) indexes.

Creating a TTL Index

If your documents contain an expiration timestamp (e.g., expiresAt), you can create a TTL index to automatically remove expired records:

db.password_reset.createIndex({ expiresAt: 1 }, { expireAfterSeconds: 0 })

How It Works

• The expiresAt field must be of type Date.
• The index ensures that documents are deleted as soon as their expiresAt timestamp is reached.
• expireAfterSeconds: 0 means the document is removed exactly at the given expiresAt time.

Verifying the Index

To check if the TTL index was successfully created, run:

db.password_reset.getIndexes()

This should display an entry with expireAfterSeconds: 0.

Ensuring expiresAt Is a Date Type

Verify that your documents store expiresAt as an ISODate:

db.password_reset.find({}, { expiresAt: 1 }).limit(5)

If necessary, convert it:

db.password_reset.updateMany(
  {},
  [{ $set: { expiresAt: { $toDate: "$expiresAt" } } }]
)

Conclusion

TTL indexes provide an efficient way to automatically remove expired documents without requiring manual cleanup or cron jobs.