Strange behavior with wired tiger oplog and duplicate ts values

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    • Type: Bug
    • Resolution: Done
    • Priority: Minor - P4
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    • Affects Version/s: None
    • Component/s: Replication, Storage
    • None
    • Replication
    • ALL
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      It seems like inserts are fine with duplicate ts values but mask older documents, or replace them.

      test:PRIMARY> db.getSiblingDB("local").oplog.rs.insert({ts: new Timestamp(1444669076,3), op:"n", h: NumberLong("12312")})
WriteResult({ "nInserted" : 1 })
test:PRIMARY> db.getSiblingDB("local").oplog.rs.insert({ts: new Timestamp(1444669076,3), op:"n", h: NumberLong("12312")})
WriteResult({ "nInserted" : 1 })
test:PRIMARY> db.getSiblingDB("local").oplog.rs.insert({ts: new Timestamp(1444669076,3), op:"n", h: NumberLong("12312")})
WriteResult({ "nInserted" : 1 })
test:PRIMARY> db.getSiblingDB("local").oplog.rs.find()
{ "_id" : ObjectId("561d0d5e30adac216043a161"), "ts" : Timestamp(1444669076, 3), "op" : "n", "h" : NumberLong(12312) }
{ "ts" : Timestamp(1444669605, 1), "t" : NumberLong(0), "h" : NumberLong("-6898850243195961135"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "initiating set" } }
{ "ts" : Timestamp(1444669606, 1), "t" : NumberLong(1), "h" : NumberLong("-1589401225501337977"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "new primary" } }
{ "ts" : Timestamp(1444669631, 1), "t" : NumberLong(1), "h" : NumberLong("1621003532950817417"), "v" : 2, "op" : "n", "ns" : "", "o" : { "foo" : 1 } }
{ "ts" : Timestamp(1444744494, 1), "t" : NumberLong(2), "h" : NumberLong("-7504719105121076257"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "new primary" } }
test:PRIMARY> db.getSiblingDB("local").oplog.rs.insert({ts: new Timestamp(1444669076,3), op:"n", h: NumberLong("12312")})
WriteResult({ "nInserted" : 1 })
test:PRIMARY> db.getSiblingDB("local").oplog.rs.find()
{ "_id" : ObjectId("561d0d6930adac216043a162"), "ts" : Timestamp(1444669076, 3), "op" : "n", "h" : NumberLong(12312) }
{ "ts" : Timestamp(1444669605, 1), "t" : NumberLong(0), "h" : NumberLong("-6898850243195961135"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "initiating set" } }
{ "ts" : Timestamp(1444669606, 1), "t" : NumberLong(1), "h" : NumberLong("-1589401225501337977"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "new primary" } }
{ "ts" : Timestamp(1444669631, 1), "t" : NumberLong(1), "h" : NumberLong("1621003532950817417"), "v" : 2, "op" : "n", "ns" : "", "o" : { "foo" : 1 } }
{ "ts" : Timestamp(1444744494, 1), "t" : NumberLong(2), "h" : NumberLong("-7504719105121076257"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "new primary" } }
test:PRIMARY> db.getSiblingDB("local").oplog.rs.count()
8
test:PRIMARY> db.getSiblingDB("local").oplog.rs.stats().count
8
test:PRIMARY> db.getSiblingDB("local").oplog.rs.insert({ts: new Timestamp(1444669076,3), op:"n", h: NumberLong("12312")})
WriteResult({ "nInserted" : 1 })
test:PRIMARY> db.getSiblingDB("local").oplog.rs.stats().count
9
test:PRIMARY> db.getSiblingDB("local").oplog.rs.count()
9

      The mmapv1 storage engine does not show this behavior:

      > db.getSiblingDB("local").oplog.rs.find()
{ "ts" : Timestamp(1444744966, 1), "t" : NumberLong(0), "h" : NumberLong("373345472902605703"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "initiating set" } }
{ "ts" : Timestamp(1444744967, 1), "t" : NumberLong(1), "h" : NumberLong("5520691837775396305"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "new primary" } }
test:PRIMARY> db.getSiblingDB("local").oplog.rs.insert({ts: new Timestamp(1444669076,3), op:"n", h: NumberLong("12312")})
WriteResult({ "nInserted" : 1 })
test:PRIMARY> db.getSiblingDB("local").oplog.rs.find()
{ "ts" : Timestamp(1444744966, 1), "t" : NumberLong(0), "h" : NumberLong("373345472902605703"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "initiating set" } }
{ "ts" : Timestamp(1444744967, 1), "t" : NumberLong(1), "h" : NumberLong("5520691837775396305"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "new primary" } }
{ "_id" : ObjectId("561d0f0e30adac216043a164"), "ts" : Timestamp(1444669076, 3), "op" : "n", "h" : NumberLong(12312) }
test:PRIMARY> db.getSiblingDB("local").oplog.rs.insert({ts: new Timestamp(1444669076,3), op:"n", h: NumberLong("12312")})
WriteResult({ "nInserted" : 1 })
test:PRIMARY> db.getSiblingDB("local").oplog.rs.insert({ts: new Timestamp(1444669076,3), op:"n", h: NumberLong("12312")})
WriteResult({ "nInserted" : 1 })
test:PRIMARY> db.getSiblingDB("local").oplog.rs.find()
{ "ts" : Timestamp(1444744966, 1), "t" : NumberLong(0), "h" : NumberLong("373345472902605703"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "initiating set" } }
{ "ts" : Timestamp(1444744967, 1), "t" : NumberLong(1), "h" : NumberLong("5520691837775396305"), "v" : 2, "op" : "n", "ns" : "", "o" : { "msg" : "new primary" } }
{ "_id" : ObjectId("561d0f0e30adac216043a164"), "ts" : Timestamp(1444669076, 3), "op" : "n", "h" : NumberLong(12312) }
{ "_id" : ObjectId("561d0f1330adac216043a165"), "ts" : Timestamp(1444669076, 3), "op" : "n", "h" : NumberLong(12312) }
{ "_id" : ObjectId("561d0f1430adac216043a166"), "ts" : Timestamp(1444669076, 3), "op" : "n", "h" : NumberLong(12312) }

        1. oplog_insert_duplicate_ts.js
          2 kB

            Assignee:
            [DO NOT USE] Backlog - Replication Team
            Reporter:
            Scott Hernandez (Inactive)
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              Created:
              Updated:
              Resolved: