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  1. Core Server
  2. SERVER-44238

mapReduce fails to merge with sharded output in different database

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    • Type: Icon: Bug Bug
    • Resolution: Won't Fix
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: MapReduce
    • None
    • ALL
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      (function() {
"use strict";
const st = new ShardingTest({shards: 2});
const db = st.s.getDB("test");
assert.commandWorked(db.adminCommand({enableSharding: "test"}));
assert.commandWorked(db.adminCommand({enableSharding: "foreign"}));
const inputColl = db.input;
const outputCollOtherDB = db.getSiblingDB("foreign").output;
assert.commandWorked(
    db.adminCommand({shardCollection: inputColl.getFullName(), key: {_id: "hashed"}}));
assert.commandWorked(
    db.adminCommand({shardCollection: outputCollOtherDB.getFullName(), key: {_id: "hashed"}}));

assert.commandWorked(inputColl.insert([{_id: 1}, {_id: 2}, {_id: 3}]));
assert.commandWorked(outputCollOtherDB.insert({_id: 1, value: 0}));
function mapFn() {
    emit(this._id, 1);
}
function reduceFn(key, values) {
    return Array.sum(values);
}

assert.commandWorked(inputColl.mapReduce(mapFn, reduceFn, {
    out:
        {merge: outputCollOtherDB.getName(), db: outputCollOtherDB.getDB().getName(), sharded: true}
}));

st.stop();
}());
      Show
      ( function () { "use strict" ; const st = new ShardingTest({shards: 2}); const db = st.s.getDB( "test" ); assert.commandWorked(db.adminCommand({enableSharding: "test" })); assert.commandWorked(db.adminCommand({enableSharding: "foreign" })); const inputColl = db.input; const outputCollOtherDB = db.getSiblingDB( "foreign" ).output; assert.commandWorked( db.adminCommand({shardCollection: inputColl.getFullName(), key: {_id: "hashed" }})); assert.commandWorked( db.adminCommand({shardCollection: outputCollOtherDB.getFullName(), key: {_id: "hashed" }})); assert.commandWorked(inputColl.insert([{_id: 1}, {_id: 2}, {_id: 3}])); assert.commandWorked(outputCollOtherDB.insert({_id: 1, value: 0})); function mapFn() { emit( this ._id, 1); } function reduceFn(key, values) { return Array.sum(values); } assert.commandWorked(inputColl.mapReduce(mapFn, reduceFn, { out: {merge: outputCollOtherDB.getName(), db: outputCollOtherDB.getDB().getName(), sharded: true } })); st.stop(); }());

      The attached reproduction script fails with:

      [js_test:repro] 2019-10-24T18:52:40.920-0400 2019-10-24T18:52:40.920-0400 E  QUERY    [js] uncaught exception: Error: map reduce failed:{
[js_test:repro] 2019-10-24T18:52:40.921-0400 	"ok" : 0,
[js_test:repro] 2019-10-24T18:52:40.921-0400 	"errmsg" : "MR post processing failed: { operationTime: Timestamp(1571957560, 122), ok: 0.0, errmsg: \"The upsert document could not be inserted onto the shard targeted by the query, since its shard key belongs on a different shard. Cross-shard upserts ...\", code: 20, codeName: \"IllegalOperation\", $gleStats: { lastOpTime: { ts: Timestamp(1571957560, 122), t: 1 }, electionId: ObjectId('7fffffff0000000000000001') }, lastCommittedOpTime: Timestamp(1571957560, 113), $configServerState: { opTime: { ts: Timestamp(1571957560, 114), t: 1 } }, $clusterTime: { clusterTime: Timestamp(1571957560, 123), signature: { hash: BinData(0, 0000000000000000000000000000000000000000), keyId: 0 } } }",
[js_test:repro] 2019-10-24T18:52:40.921-0400 	"operationTime" : Timestamp(1571957560, 124),
[js_test:repro] 2019-10-24T18:52:40.921-0400 	"$clusterTime" : {
[js_test:repro] 2019-10-24T18:52:40.921-0400 		"clusterTime" : Timestamp(1571957560, 124),
[js_test:repro] 2019-10-24T18:52:40.921-0400 		"signature" : {
[js_test:repro] 2019-10-24T18:52:40.921-0400 			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
[js_test:repro] 2019-10-24T18:52:40.921-0400 			"keyId" : NumberLong(0)
[js_test:repro] 2019-10-24T18:52:40.921-0400 		}
[js_test:repro] 2019-10-24T18:52:40.921-0400 	}
[js_test:repro] 2019-10-24T18:52:40.921-0400 } :
[js_test:repro] 2019-10-24T18:52:40.921-0400 _getErrorWithCode@src/mongo/shell/utils.js:25:13
[js_test:repro] 2019-10-24T18:52:40.921-0400 DBCollection.prototype.mapReduce@src/mongo/shell/collection.js:1085:15
[js_test:repro] 2019-10-24T18:52:40.921-0400 @repro.js:23:22
[js_test:repro] 2019-10-24T18:52:40.921-0400 @repro.js:1:2

            Assignee:
            charlie.swanson@mongodb.com Charlie Swanson
            Reporter:
            charlie.swanson@mongodb.com Charlie Swanson
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            Watchers:
            3 Start watching this issue

              Created:
              Updated:
              Resolved: