Fix or document impact of timeseries upgrade/downgrade on snapshot reads

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    • Type: Task
    • Resolution: Duplicate
    • Priority: Major - P3
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    • Affects Version/s: 8.3.0-rc0
    • Component/s: Catalog, Upgrade/Downgrade
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    • Catalog and Routing
    • 🟦 Shard Catalog
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      Time series collection have limitations for snapshot reads stemming from views not supporting point-in-time reads (SERVER-74429).

       

      After we do the timeseries upgrade/downgrade, the view is dropped. This is problematic for snapshot reads, for example if they read at a timestamp before to the upgrade:

      Reproduction steps (requires SERVER-114505):

      > db.adminCommand({setFeatureCompatibilityVersion: "8.0", confirm: true})
> db.createCollection("myts", {timeseries:{timeField:'t'}})
> db.myts.insertOne({t:ISODate()})
> const beforeUpgradeTime = db.getMongo().getClusterTime().clusterTime
> db.myts.aggregate([], {readConcern: {level: "snapshot", atClusterTime: beforeUpgradeTime}}).toArray()
[
    {
        "t" : ISODate("2025-11-28T11:32:08.157Z"),
        "_id" : ObjectId("692988389629f921a1d99976")
    }
]
> db.adminCommand({setFeatureCompatibilityVersion: "8.3", confirm: true})
> assert(db.getSiblingDB("local").oplog.rs.findOne({"o.upgradeDowngradeViewlessTimeseries": "myts"}))
> db.myts.aggregate([], {readConcern: {level: "snapshot", atClusterTime: beforeUpgradeTime}}).toArray()
[ ]

       

      Investigate if code or documentation changes are necessary.

            Assignee:
            Unassigned
            Reporter:
            Joan Bruguera Micó
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              Created:
              Updated:
              Resolved: