CODEWITHSUNDEEP
node.jsmongodbmongoose
karma
karma

Reputation: 923

TTL mongo for specific entry array

I read that mongodb has TTL (Time to live) indexes that can be activated for document.

But does it work if document structure is as follows?

username: 'user x',
activity: [
  {type:a, desc:1, timestamp:timestamp},
  {type:b, desc:2, timestamp:timestamp},
  {type:b, desc:3, timestamp:timestamp},
  etc.
]

Is there possibility to set TTL based on timestamp+7days of each array item so that only those expires but recent ones are kept?

Upvotes: 4

Views: 1751

Answers (2)

Jespertheend
Jespertheend

Reputation: 2260

There's currently no way to delete specific elements from an array using a TTL index. There's a feature request for this, but it seems like at the moment the best way to do this is to create a separate collection that links to the _id of your documents.

So in your case, instead of adding an activity array to all your users, you create an extra activities collections which contains documents like this:

{type:a, desc:1, timestamp:timestamp, userId:ObjectId("611636e533f29e4bd6683b05")}
{type:b, desc:2, timestamp:timestamp, userId:ObjectId("611636e533f29e4bd6683b05")}
{type:b, desc:3, timestamp:timestamp, userId:ObjectId("611636e533f29e4bd6683b05")}

Upvotes: 0

Kevin Smith
Kevin Smith

Reputation: 14436

Read the documentation carefully, The TTL index can be applied to an array but it will delete the whole document when expired not just the element inside the array.

However, you could split the array out into many documents?

Upvotes: 4

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