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Type:
Bug
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Resolution: Done
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Priority:
Major - P3
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Affects Version/s: 3.2.0
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Component/s: mongorestore
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Labels:None
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Server Tools 10 (02/19/16)
An empty collection will be dumped as a 0 byte .bson file. When running mongorestore normally, the empty collection will be correctly created. However, if --noIndexRestore is specified then the empty collection will not be created. If the server is running 3.2, then this prevents subsequent oplog replay from working (SERVER-17634), which impedes the workaround for TOOLS-176.
Reproducer:
> use test
> db.dropDatabase()
> db.createCollection("test")
$ mongodump
> db.dropDatabase()
> show collections // returns nothing
$ mongorestore
> show collections // shows "test"
> db.adminCommand({applyOps: [ { ts: Timestamp(1452934862,5), h: NumberLong("6736086318751491068"), v: 2, op: "i", ns: "test.test", o: { _id: 1 }, o2: {} } ] }) // succeeds
{ "applied" : 1, "results" : [ true ], "ok" : 1 }
> db.dropDatabase()
$ mongorestore --noIndexRestore
> show collections // returns nothing, but should show "test"
> db.adminCommand({applyOps: [ { ts: Timestamp(1452934862,5), h: NumberLong("6736086318751491068"), v: 2, op: "i", ns: "test.test", o: { _id: 1 }, o2: {} } ] }) // fails with:
{
"applied" : 1,
"code" : 26,
"errmsg" : "Failed to apply insert due to missing collection: { ts: Timestamp 1452934862000|5, h: 6736086318751491068, v: 2.0, op: \"i\", ns: \"test.test\", o: { _id: 1.0 }, o2: {} }",
"results" : [
false
],
"ok" : 0
}
Workaround:
Instead of doing:
mongorestore --noIndexRestore --oplogReplay dump
it is possible to do:
mongo --eval 'db.getSiblingDB("db").createCollection("collection")' # repeat for each empty collection, ie. each 0 byte .bson file under `dump` mongorestore --noIndexRestore --oplogReplay dump
However, if --drop is used then the workaround is more complicated. Instead of doing:
mongorestore --drop --noIndexRestore --oplogReplay dump
it should be possible to do:
mongorestore --drop --noIndexRestore dump mongo --eval 'db.getSiblingDB("db").createCollection("collection")' # repeat for each empty collection, ie. each 0 byte .bson file under `dump` mkdir justoplog ; mv data/oplog.bson justoplog mongorestore --oplogReplay --noIndexRestore justoplog
- related to
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- Closed
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TOOLS-852 mongorestore --noDataRestore
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- Accepted
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SERVER-17634 do not apply replicated insert operations on missing collections
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- Closed
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