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I want to know if it's possible to use TTL on nested documents.
I have Account and inside I have Sessions. Sessions need to expire in 30 minutes. I've set everything up but obviously when I set TTL index on Account.Sessions.EndDateTime it removes the whole Account. Can I make sure it removes only Session?
This is what it looks like in database. Notice how it will delete whole Account and not only Session when EndDateTime will come.
{
"_id" : ObjectId("53af273888dba003f429540b"),
"Email" : "[email protected]",
"PasswordHash" : "CZaBEQRbwWNgJBjyhks7gH0Z3v5ZvDkW29pryF0DEXyE8rIw0NA4x39+uQneArKaUv97sP1e+e22YT1glbqQsw==",
"PasswordSalt" : "100000.Qx4D8uj7oDcWHRTLGRRTDwVkw2UcaM52XkDR9k2ga073Ow==",
"Sessions" : [
{
"Token" : "da55cf0783c4249b26283948fcae6caa15df320ca456203045aea81cad691df8",
"IpAddress" : "::1",
"StartDateTime" : ISODate("2014-06-28T20:36:27.000Z"),
"EndDateTime" : ISODate("2014-06-28T21:06:27.000Z")
}
]
}
This is where I create said index.
if (!_db.Accounts.IndexExists("Sessions.EndDateTime"))
{
_db.Accounts.CreateIndex(IndexKeys.Ascending("Sessions.EndDateTime"),
IndexOptions.SetTimeToLive(new TimeSpan(0)));
}
786
The TTL feature relies on a background thread in mongod that reads the date-typed values in the index and removes expired documents from the collection.
TTL indexes are special single-field indexes that MongoDB can use to automatically remove documents from a collection after a certain amount of time or at a specific clock time.
MongoDB delivers an upstanding feature named Embedded or Nested Document. An Embedded or Nested Document is a type of document that contains one document within another.
Accessing embedded/nested documents – In MongoDB, you can access the fields of nested/embedded documents of the collection using dot notation and when you are using dot notation, then the field and the nested field must be inside the quotation marks.
That is currently not possible with TTL index. Mongod will remove the whole document after a specified number of seconds or at a specific clock time.
TTL relies on a background thread in mongod that reads the date-typed values in the index and removes expired documents from the collection.
I would recommend that you store the session sub-document in a separate collection and add a TTL index on that collection.
If you can't change your schema, the alternative is to create a background job that will delete nested documents from your collection every 60 seconds.
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