MongoDB query for document older than 30 seconds

Question

Does anyone have a good approach for a query against a collection for documents that are older than 30 seconds. I'm creating a cleanup worker that marks items as failed after they have been in a specific state for more than 30 seconds. Not that it matters, but I'm using mongojs for this one. Every document has a `created` time associated with it.

Accepted Answer

We are assuming you have a `created_at` or similar field in your document that has the time it was inserted or otherwise modified depending on which is important to you.

Rather than iterate over the results you might want to look at the `multi` option in update to apply your change to all documents that match your query. Setting the time you want to look past should be fairly straightforward

In shell syntax, which should be pretty much the same of the driver:

```
db.collection.update({
     created_at: {$lt: time },
     state: oldstate 
},
{$set: { state: newstate } }, false, true )
```

The first `false` being for upserts which does not make any sense in this usage and the second `true` marking for `multi` document update.

If the documents are indeed going to be short lived and you have no other need for them afterwards, then you might consider capped collections. You can have a `total size` or `time to live` option for these and the natural insertion order favours processing of queued entries.

MongoDB query for document older than 30 seconds

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