MongoDB ttl index behave unexpected

Question

We currently have a ttl index on a timestamp in MongoDB.

Before we had an ttl expireAfterSeconds : 604800 seconds -> 1 week of documents.

A few weeks ago we change this to a TTL index of 31536000 seconds -> 365 days.

But MongoDB still removes documents after 7 days instead of 365.

MongoDB version: 4.2.18
MongoDB running hosted Atlas / AWS

Indexes in database:

  {
    v: 2,
    key: { _id: 1 },
    name: '_id_',
    ns: '<DB>.<COLLECTION>'
  },
  {
    v: 2,
    key: { id: 1, ts: 1 },
    name: 'id_1_ts_1',
    ns: '<DB>.<COLLECTION>
  },
  {
    v: 2,
    key: { ts: 1 },
    name: 'ts_1',
    ns: '<DB>.<COLLECTION>',
    expireAfterSeconds: 31536000
  }
]

We have an environmental variable to set the TTL index on each start of the application, the code to set the ttl index looks like this:

      await collection.createIndex(
        { ts: 1 },
        {
          expireAfterSeconds: ENV.<Number>
        }
      );
    } catch (e) {
      if ((e as any).codeName == "IndexOptionsConflict") {
        await collection.dropIndex("ts_1");
        await collection.createIndex(
          { ts: 1 },
          {
            expireAfterSeconds: ENV.<Number>
          }
        );
      }
    }

as seen from the indexes, the TTL index should remove documents after one year? Why does it behave like this? Any insights?

How did you change the `expireAfterSeconds` value for the index? — prasad_, Feb 17 '22 at 13:38
I think, you need to specify the _index name_ in the `await collection.dropIndex("ts");`. — prasad_, Feb 18 '22 at 09:54
We actually do it, I accidentally removed it while removing the real key names. Edited abobe. — Villeviktor, Feb 21 '22 at 08:15
Maybe you should drop the index first, and then create the new index. — prasad_, Feb 21 '22 at 08:19

score -1 · Answer 1 · answered Mar 31 '22 at 19:22

-1

I would look into the collMod command

answered Mar 31 '22 at 19:22

Dan Mullen

1

1

Please add some code to address the issue or link to a similar question with an answer. More description needed – Usman Shaukat Mar 31 '22 at 19:41

MongoDB ttl index behave unexpected

1 Answers1