Dropping admin db sets FCV to 3.4 but leaves UUIDs

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    • Type: Bug
    • Resolution: Fixed
    • Priority: Major - P3
    • 3.6.3, 3.7.2
    • Affects Version/s: 3.6.0
    • Component/s: Upgrade/Downgrade
    • None
    • Fully Compatible
    • ALL
    • v3.6
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      The following shows how dropping the admin db may leave UUIDs.

      test> db.adminCommand({getParameter: 1, featureCompatibilityVersion: 1})
{ "featureCompatibilityVersion" : { "version" : "3.6" }, "ok" : 1 }
test> use local
switched to db local
local> db.runCommand({listCollections: 1})
{
    "cursor" : {
        "id" : NumberLong(0),
        "ns" : "local.$cmd.listCollections",
        "firstBatch" : [
            {
                "name" : "startup_log",
                "type" : "collection",
                "options" : {
                    "capped" : true,
                    "size" : 10485760
                },
                "info" : {
                    "readOnly" : false,
                    "uuid" : BinData(4,"8Vlh0RQDSSy2HRFJJlBVDQ==")
                },
                "idIndex" : {
                    "v" : 2,
                    "key" : {
                        "_id" : 1
                    },
                    "name" : "_id_",
                    "ns" : "local.startup_log"
                }
            }
        ]
    },
    "ok" : 1
}
local> use admin
switched to db admin
admin> db.dropDatabase()
{ "dropped" : "admin", "ok" : 1 }
admin> db.adminCommand({getParameter: 1, featureCompatibilityVersion: 1})
{ "featureCompatibilityVersion" : { "version" : "3.4" }, "ok" : 1 }
admin> use local
switched to db local
local> db.runCommand({listCollections: 1})
{
    "cursor" : {
        "id" : NumberLong(0),
        "ns" : "local.$cmd.listCollections",
        "firstBatch" : [
            {
                "name" : "startup_log",
                "type" : "collection",
                "options" : {
                    "capped" : true,
                    "size" : 10485760
                },
                "info" : {
                    "readOnly" : false,
                    "uuid" : BinData(4,"8Vlh0RQDSSy2HRFJJlBVDQ==")
                },
                "idIndex" : {
                    "v" : 2,
                    "key" : {
                        "_id" : 1
                    },
                    "name" : "_id_",
                    "ns" : "local.startup_log"
                }
            }
        ]
    },
    "ok" : 1
}
local> db.adminCommand({getParameter: 1, featureCompatibilityVersion: 1})
{ "featureCompatibilityVersion" : { "version" : "3.4" }, "ok" : 1 }
local> db.version()

      As shown, info.uuid is still present in the local.startup_log collection.

      Show
      The following shows how dropping the admin db may leave UUIDs. test> db.adminCommand({getParameter: 1, featureCompatibilityVersion: 1}) { "featureCompatibilityVersion" : { "version" : "3.6" }, "ok" : 1 } test> use local switched to db local local> db.runCommand({listCollections: 1}) { "cursor" : { "id" : NumberLong(0), "ns" : "local.$cmd.listCollections" , "firstBatch" : [ { "name" : "startup_log" , "type" : "collection" , "options" : { "capped" : true , "size" : 10485760 }, "info" : { "readOnly" : false , "uuid" : BinData(4, "8Vlh0RQDSSy2HRFJJlBVDQ==" ) }, "idIndex" : { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_" , "ns" : "local.startup_log" } } ] }, "ok" : 1 } local> use admin switched to db admin admin> db.dropDatabase() { "dropped" : "admin" , "ok" : 1 } admin> db.adminCommand({getParameter: 1, featureCompatibilityVersion: 1}) { "featureCompatibilityVersion" : { "version" : "3.4" }, "ok" : 1 } admin> use local switched to db local local> db.runCommand({listCollections: 1}) { "cursor" : { "id" : NumberLong(0), "ns" : "local.$cmd.listCollections" , "firstBatch" : [ { "name" : "startup_log" , "type" : "collection" , "options" : { "capped" : true , "size" : 10485760 }, "info" : { "readOnly" : false , "uuid" : BinData(4, "8Vlh0RQDSSy2HRFJJlBVDQ==" ) }, "idIndex" : { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_" , "ns" : "local.startup_log" } } ] }, "ok" : 1 } local> db.adminCommand({getParameter: 1, featureCompatibilityVersion: 1}) { "featureCompatibilityVersion" : { "version" : "3.4" }, "ok" : 1 } local> db.version() As shown, info.uuid is still present in the local.startup_log collection.
    • Storage 2018-01-01, Storage 2018-01-15, Storage 2018-02-12
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      Dropping the admin database sets FCV to 3.4 but does not downgrade properly. E.g. UUIDs still remain in the collection catalog.

      This is only possible on a standalone mongod, replset nodes disallow this.

      As discussed, maybe we don't want to allow users to drop admin database.

            Assignee:
            Maria van Keulen
            Reporter:
            Kevin Albertson
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              Created:
              Updated:
              Resolved: