-
Type:
Bug
-
Resolution: Won't Fix
-
Priority:
Major - P3
-
None
-
Affects Version/s: None
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Component/s: Aggregation Framework
-
ALL
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Query 2020-01-27, Query 2020-02-10, Query 2020-03-09
- MongoDB 4.0.7 add mergeByPBRT option between mongos and mongod
- if mongos has upgraded to a new version，the normal aggregation command to mongod below 4.0.7 will cause access error.
mongos> db.test.aggregate([{"$match":{"c32":17}}, {"$group":{"_id":null, "total":{"$sum":"$float"}}}])
2019-12-30T19:59:16.398+0800 E QUERY [js] Error: command failed: {
"ok" : 0,
"errmsg" : "unrecognized field 'mergeByPBRT'",
"code" : 9,
"codeName" : "FailedToParse",
"operationTime" : Timestamp(1577707153, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1577707155, 3),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
Workaround，only add mergeByPBRT option in change stream aggregation command.
diff --git a/src/mongo/s/commands/cluster_aggregate.cpp b/src/mongo/s/commands/cluster_aggregate.cpp
index d58ce76220..a2c308a353 100644
--- a/src/mongo/s/commands/cluster_aggregate.cpp
+++ b/src/mongo/s/commands/cluster_aggregate.cpp
@@ -215,7 +215,9 @@ BSONObj createCommandForTargetedShards(
targetedCmd[AggregationRequest::kNeedsMergeName] = Value(true);
// If this is a change stream, set the 'mergeByPBRT' flag on the command. This notifies
// the shards that the mongoS is capable of merging streams based on resume token.
- targetedCmd[AggregationRequest::kMergeByPBRTName] = Value(litePipe.hasChangeStream());
+ if (litePipe.hasChangeStream()) {
+ targetedCmd[AggregationRequest::kMergeByPBRTName] = Value(litePipe.hasChangeStream());
+ }
targetedCmd[AggregationRequest::kCursorName] =
Value(DOC(AggregationRequest::kBatchSizeName << 0));
}