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  1. Core Server
  2. SERVER-74794

PeriodicShardedIndexConsistencyChecker fails with error "unrecognized field 'let'"

    • Type: Icon: Bug Bug
    • Resolution: Won't Fix
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: 5.0.15
    • Component/s: None
    • Labels:
      None
    • Query Optimization
    • ALL
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      Upgrade the config servers in a sharded 4.4 cluster that has some indexes defined to 5.0.

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      Upgrade the config servers in a sharded 4.4 cluster that has some indexes defined to 5.0.

      We have begin upgrading one of our 4.4.16 clusters to 5.0.15. So far, only the config servers and 2 shard replicas have been upgraded. Since upgrading these nodes to 5.0.15, we see the following logged every 10 minutes:

      {"t":{"$date":"2023-03-13T17:33:50.005+00:00"},"s":"I",  "c":"SHARDING", "id":22049,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Checking consistency of sharded collection indexes across the cluster"}
      {"t":{"$date":"2023-03-13T17:33:50.162+00:00"},"s":"I",  "c":"SHARDING", "id":22052,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Error while checking sharded index consistency","attr":{"error":{"code":9,"codeName":"FailedToParse","errmsg":"unrecognized field 'let'"}}} 

      I enabled debug logging for the "sharding" and "query" components and was able to obtain additional details about the 'let' it's referring to:

       

      {"t":{"$date":"2023-03-13T17:43:50.005+00:00"},"s":"I",  "c":"SHARDING", "id":22049,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Checking consistency of sharded collection indexes across the cluster"}
      {"t":{"$date":"2023-03-13T17:43:50.005+00:00"},"s":"D5", "c":"QUERY",    "id":20967,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Beginning planning","attr":{"options":"INDEX_INTERSECTION SPLIT_LIMITED_SORT ","query":"ns=config.collectionsTree: $and\nSort: {}\nProj: {}\n"}}
      {"t":{"$date":"2023-03-13T17:43:50.005+00:00"},"s":"D5", "c":"QUERY",    "id":20968,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Index number and details","attr":{"indexNumber":0,"index":"kp: { _id: 1 } unique name: '(_id_, )' io: { v: 2, key: { _id: 1 }, name: \"_id_\" }"}}
      {"t":{"$date":"2023-03-13T17:43:50.005+00:00"},"s":"D5", "c":"QUERY",    "id":20972,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Rated tree","attr":{"tree":"$and\n"}}
      {"t":{"$date":"2023-03-13T17:43:50.005+00:00"},"s":"D5", "c":"QUERY",    "id":20979,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Planner: outputted indexed solutions","attr":{"numSolutions":0}}
      {"t":{"$date":"2023-03-13T17:43:50.005+00:00"},"s":"D5", "c":"QUERY",    "id":20984,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Planner: outputting a collection scan","attr":{"collectionScan":"COLLSCAN\n---ns = config.collections\n---filter = $and\n---nodeId = 1\n---fetched = 1\n---sortedByDiskLoc = 0\n---providedSorts = {baseSortPattern: {}, ignoredFields: []}\n"}}
      {"t":{"$date":"2023-03-13T17:43:50.005+00:00"},"s":"D5", "c":"QUERY",    "id":5400802, "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"collection scan bounds","attr":{"min":"none","max":"none"}}
      {"t":{"$date":"2023-03-13T17:43:50.005+00:00"},"s":"D2", "c":"QUERY",    "id":20926,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Only one plan is available; it will be run but will not be cached","attr":{"query":"ns: config.collections query: {} sort: {} projection: {}","planSummary":"COLLSCAN"}}
      {"t":{"$date":"2023-03-13T17:43:50.147+00:00"},"s":"D5", "c":"QUERY",    "id":20725,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Expression prior to rewrite","attr":{"expression":"{$or: [{$gt: [{$size: [\"$missingFromShards\"]}, {$const: 0}]}, {$gt: [{$size: [\"$inconsistentProperties\"]}, {$const: 0}]}]}"}}
      {"t":{"$date":"2023-03-13T17:43:50.147+00:00"},"s":"D5", "c":"QUERY",    "id":20967,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Beginning planning","attr":{"options":"NO_TABLE_SCAN ","query":"ns=AAA.ClusterSettingsTree: $and\nSort: {}\nProj: {}\nCollation: { locale: \"simple\" }\n"}}
      {"t":{"$date":"2023-03-13T17:43:50.147+00:00"},"s":"D5", "c":"QUERY",    "id":20968,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Index number and details","attr":{"indexNumber":0,"index":"kp: { _id: 1 } name: '(shardkey, )'"}}
      {"t":{"$date":"2023-03-13T17:43:50.147+00:00"},"s":"D5", "c":"QUERY",    "id":20972,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Rated tree","attr":{"tree":"$and\n"}}
      {"t":{"$date":"2023-03-13T17:43:50.147+00:00"},"s":"D5", "c":"QUERY",    "id":20979,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Planner: outputted indexed solutions","attr":{"numSolutions":0}}
      {"t":{"$date":"2023-03-13T17:43:50.147+00:00"},"s":"D1", "c":"QUERY",    "id":20904,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Dispatching command {cmdObj} to establish cursors on shards","attr":{"cmdObj":{"aggregate":"ClusterSettings","pipeline":[{"$indexStats":{}},{"$group":{"_id":{"$const":null},"indexDoc":{"$push":"$$ROOT"},"allShards":{"$addToSet":"$shard"}}},{"$unwind":{"path":"$indexDoc"}},{"$group":{"_id":"$indexDoc.name","shards":{"$push":"$indexDoc.shard"},"specs":{"$push":{"$objectToArray":[{"$ifNull":["$indexDoc.spec",{"$const":{}}]}]}},"allShards":{"$first":"$allShards"}}},{"$project":{"_id":true,"missingFromShards":{"$setDifference":["$allShards","$shards"]},"inconsistentProperties":{"$setDifference":[{"$reduce":{"input":"$specs","initialValue":{"$arrayElemAt":["$specs",{"$const":0}]},"in":{"$setUnion":["$$value","$$this"]}}},{"$reduce":{"input":"$specs","initialValue":{"$arrayElemAt":["$specs",{"$const":0}]},"in":{"$setIntersection":["$$value","$$this"]}}}]}}},{"$match":{"$expr":{"$or":[{"$gt":[{"$size":"$missingFromShards"},0]},{"$gt":[{"$size":"$inconsistentProperties"},0]}]}}},{"$project":{"inconsistentProperties":true,"missingFromShards":true,"indexName":"$$ROOT._id","_id":false}},{"$limit":1}],"cursor":{"batchSize":101},"let":{"NOW":{"$date":"2023-03-13T17:43:50.147Z"},"CLUSTER_TIME":{"$timestamp":{"t":1678729430,"i":159}}},"fromMongos":true,"collation":{"locale":"simple"},"readConcern":{"provenance":"implicitDefault"},"writeConcern":{"w":1,"wtimeout":0}}}}
      {"t":{"$date":"2023-03-13T17:43:50.147+00:00"},"s":"D3", "c":"QUERY",    "id":4625502, "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Establishing cursors on remotes","attr":{"opId":21823852,"numRemotes":1,"opKey":{"uuid":{"$uuid":"7f913566-8991-477c-8711-3e8182a2d278"}}}}
      {"t":{"$date":"2023-03-13T17:43:50.149+00:00"},"s":"D3", "c":"QUERY",    "id":4674000, "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Experienced a failure while establishing cursors","attr":{"error":{"code":9,"codeName":"FailedToParse","errmsg":"unrecognized field 'let'"}}}
      {"t":{"$date":"2023-03-13T17:43:50.149+00:00"},"s":"I",  "c":"QUERY",    "id":4625501, "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Unable to establish remote cursors","attr":{"error":{"code":9,"codeName":"FailedToParse","errmsg":"unrecognized field 'let'"},"nRemotes":0}}
      {"t":{"$date":"2023-03-13T17:43:50.163+00:00"},"s":"I",  "c":"SHARDING", "id":22052,   "ctx":"PeriodicShardedIndexConsistencyChecker","msg":"Error while checking sharded index consistency","attr":{"error":{"code":9,"codeName":"FailedToParse","errmsg":"unrecognized field 'let'"}}} 

       

      I'm thinking perhaps 'let' is a new option that was added in 5.0. If so, the command should not be attempting to use it until all nodes in the cluster are 5.0 (or maybe check if fCV is 5.0).

       

            Assignee:
            backlog-query-optimization [DO NOT USE] Backlog - Query Optimization
            Reporter:
            ian.springer@salesforce.com Ian Springer
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              Created:
              Updated:
              Resolved: