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  1. Core Server
  2. SERVER-28952

Multikey indexes should not be eligible for DISTINCT_SCAN if distinct key is an array component

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Critical - P2
    • Resolution: Fixed
    • Affects Version/s: 3.4.4
    • Fix Version/s: 3.4.5, 3.5.7
    • Component/s: Querying
    • Labels:
      None
    • Backwards Compatibility:
      Fully Compatible
    • Operating System:
      ALL
    • Backport Requested:
      v3.4
    • Steps To Reproduce:
      Hide

      > use test_distinct
      switched to db test_distinct
       
      > db.Item.insert({label:"L1",content:["A","B","C"]})
      WriteResult({ "nInserted" : 1 })
      > db.Item.insert({label:"L1",content:["B","C","D"]})
      WriteResult({ "nInserted" : 1 })
      > db.Item.insert({label:"L1",content:["C","D","E"]})
      WriteResult({ "nInserted" : 1 })
      > db.Item.insert({label:"L2",content:["a","b","c"]})
      WriteResult({ "nInserted" : 1 })
      > db.Item.insert({label:"L2",content:["b","c","d"]})
      WriteResult({ "nInserted" : 1 })
       
      > db.Item.distinct("content")
      [ "A", "B", "C", "D", "E", "a", "b", "c", "d" ]
       
      > db.Item.distinct("content",{label:"L1"})
      [ "A", "B", "C", "D", "E" ]
       
      > db.Item.distinct("content",{label:"L1",content:"C"})
      [ "A", "B", "C", "D", "E" ]
       
      > db.Item.createIndex({label:1,content:1})
      {
          "createdCollectionAutomatically" : false,
          "numIndexesBefore" : 1,
          "numIndexesAfter" : 2,
          "ok" : 1
      }
       
       
      // Incorrect
      > db.Item.distinct("content",{label:"L1",content:"C"})
      [ "A", "B", "C" ]
       
      > db.Item.dropIndex({label:1,content:1})
      { "nIndexesWas" : 2, "ok" : 1 }
       
      > db.Item.distinct("content",{label:"L1",content:"C"})
      [ "A", "B", "C", "D", "E" ]
      

      Show
      > use test_distinct switched to db test_distinct   > db.Item.insert({label: "L1" ,content:[ "A" , "B" , "C" ]}) WriteResult({ "nInserted" : 1 }) > db.Item.insert({label: "L1" ,content:[ "B" , "C" , "D" ]}) WriteResult({ "nInserted" : 1 }) > db.Item.insert({label: "L1" ,content:[ "C" , "D" , "E" ]}) WriteResult({ "nInserted" : 1 }) > db.Item.insert({label: "L2" ,content:[ "a" , "b" , "c" ]}) WriteResult({ "nInserted" : 1 }) > db.Item.insert({label: "L2" ,content:[ "b" , "c" , "d" ]}) WriteResult({ "nInserted" : 1 })   > db.Item.distinct( "content" ) [ "A" , "B" , "C" , "D" , "E" , "a" , "b" , "c" , "d" ]   > db.Item.distinct( "content" ,{label: "L1" }) [ "A" , "B" , "C" , "D" , "E" ]   > db.Item.distinct( "content" ,{label: "L1" ,content: "C" }) [ "A" , "B" , "C" , "D" , "E" ]   > db.Item.createIndex({label:1,content:1}) { "createdCollectionAutomatically" : false , "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 }     // Incorrect > db.Item.distinct( "content" ,{label: "L1" ,content: "C" }) [ "A" , "B" , "C" ]   > db.Item.dropIndex({label:1,content:1}) { "nIndexesWas" : 2, "ok" : 1 }   > db.Item.distinct( "content" ,{label: "L1" ,content: "C" }) [ "A" , "B" , "C" , "D" , "E" ]
    • Sprint:
      Query 2017-05-08

      Description

      > db.serverStatus()
      {
          "host" : "rinmato-MacBook-Pro.local",
          "version" : "3.4.4",
          "process" : "mongod",
          "pid" : NumberLong(4087),
          "uptime" : 278,
          "uptimeMillis" : NumberLong(277065),
          "uptimeEstimate" : NumberLong(277),
          "localTime" : ISODate("2017-04-25T06:30:29.040Z"),
          "asserts" : {
              "regular" : 0,
              "warning" : 0,
              "msg" : 0,
              "user" : 0,
              "rollovers" : 0
          },
          "connections" : {
              "current" : 2,
              "available" : 202,
              "totalCreated" : 2
          },
          "extra_info" : {
              "note" : "fields vary by platform",
              "page_faults" : 0
          },
          "globalLock" : {
              "totalTime" : NumberLong(277064000),
              "currentQueue" : {
                  "total" : 0,
                  "readers" : 0,
                  "writers" : 0
              },
              "activeClients" : {
                  "total" : 8,
                  "readers" : 0,
                  "writers" : 0
              }
          },
          "locks" : {
              "Global" : {
                  "acquireCount" : {
                      "r" : NumberLong(8148),
                      "w" : NumberLong(61),
                      "W" : NumberLong(5)
                  }
              },
              "Database" : {
                  "acquireCount" : {
                      "r" : NumberLong(4027),
                      "R" : NumberLong(12),
                      "W" : NumberLong(61)
                  }
              },
              "Collection" : {
                  "acquireCount" : {
                      "r" : NumberLong(4011)
                  }
              },
              "Metadata" : {
                  "acquireCount" : {
                      "w" : NumberLong(1)
                  }
              }
          },
          "network" : {
              "bytesIn" : NumberLong(3132),
              "bytesOut" : NumberLong(12707),
              "physicalBytesIn" : NumberLong(3132),
              "physicalBytesOut" : NumberLong(12707),
              "numRequests" : NumberLong(67)
          },
          "opLatencies" : {
              "reads" : {
                  "latency" : NumberLong(1306),
                  "ops" : NumberLong(2)
              },
              "writes" : {
                  "latency" : NumberLong(0),
                  "ops" : NumberLong(0)
              },
              "commands" : {
                  "latency" : NumberLong(12199),
                  "ops" : NumberLong(31)
              }
          },
          "opcounters" : {
              "insert" : 0,
              "query" : 1,
              "update" : 0,
              "delete" : 0,
              "getmore" : 0,
              "command" : 34
          },
          "opcountersRepl" : {
              "insert" : 0,
              "query" : 0,
              "update" : 0,
              "delete" : 0,
              "getmore" : 0,
              "command" : 0
          },
          "storageEngine" : {
              "name" : "wiredTiger",
              "supportsCommittedReads" : true,
              "readOnly" : false,
              "persistent" : true
          },
          "wiredTiger" : {
              "uri" : "statistics:",
              "LSM" : {
                  "application work units currently queued" : 0,
                  "merge work units currently queued" : 0,
                  "rows merged in an LSM tree" : 0,
                  "sleep for LSM checkpoint throttle" : 0,
                  "sleep for LSM merge throttle" : 0,
                  "switch work units currently queued" : 0,
                  "tree maintenance operations discarded" : 0,
                  "tree maintenance operations executed" : 0,
                  "tree maintenance operations scheduled" : 0,
                  "tree queue hit maximum" : 0
              },
              "async" : {
                  "current work queue length" : 0,
                  "maximum work queue length" : 0,
                  "number of allocation state races" : 0,
                  "number of flush calls" : 0,
                  "number of operation slots viewed for allocation" : 0,
                  "number of times operation allocation failed" : 0,
                  "number of times worker found no work" : 0,
                  "total allocations" : 0,
                  "total compact calls" : 0,
                  "total insert calls" : 0,
                  "total remove calls" : 0,
                  "total search calls" : 0,
                  "total update calls" : 0
              },
              "block-manager" : {
                  "blocks pre-loaded" : 1609,
                  "blocks read" : 191,
                  "blocks written" : 42,
                  "bytes read" : 1314816,
                  "bytes written" : 421888,
                  "bytes written for checkpoint" : 421888,
                  "mapped blocks read" : 0,
                  "mapped bytes read" : 0
              },
              "cache" : {
                  "application threads page read from disk to cache count" : 79,
                  "application threads page read from disk to cache time (usecs)" : 2267,
                  "application threads page write from cache to disk count" : 0,
                  "application threads page write from cache to disk time (usecs)" : 0,
                  "bytes belonging to page images in the cache" : 2110375,
                  "bytes currently in the cache" : 2423646,
                  "bytes not belonging to page images in the cache" : 313271,
                  "bytes read into cache" : 1954246,
                  "bytes written from cache" : 301882,
                  "checkpoint blocked page eviction" : 0,
                  "eviction calls to get a page" : 19,
                  "eviction calls to get a page found queue empty" : 19,
                  "eviction calls to get a page found queue empty after locking" : 0,
                  "eviction currently operating in aggressive mode" : 0,
                  "eviction empty score" : 0,
                  "eviction server candidate queue empty when topping up" : 0,
                  "eviction server candidate queue not empty when topping up" : 0,
                  "eviction server evicting pages" : 0,
                  "eviction server slept, because we did not make progress with eviction" : 0,
                  "eviction server unable to reach eviction goal" : 0,
                  "eviction state" : 16,
                  "eviction walks abandoned" : 0,
                  "eviction worker thread active" : 4,
                  "eviction worker thread created" : 0,
                  "eviction worker thread evicting pages" : 0,
                  "eviction worker thread removed" : 12,
                  "eviction worker thread stable number" : 0,
                  "failed eviction of pages that exceeded the in-memory maximum" : 0,
                  "files with active eviction walks" : 0,
                  "files with new eviction walks started" : 0,
                  "force re-tuning of eviction workers once in a while" : 2,
                  "hazard pointer blocked page eviction" : 0,
                  "hazard pointer check calls" : 0,
                  "hazard pointer check entries walked" : 0,
                  "hazard pointer maximum array length" : 0,
                  "in-memory page passed criteria to be split" : 0,
                  "in-memory page splits" : 0,
                  "internal pages evicted" : 0,
                  "internal pages split during eviction" : 0,
                  "leaf pages split during eviction" : 0,
                  "lookaside table insert calls" : 0,
                  "lookaside table remove calls" : 0,
                  "maximum bytes configured" : 8053063680,
                  "maximum page size at eviction" : 0,
                  "modified pages evicted" : 0,
                  "modified pages evicted by application threads" : 0,
                  "overflow pages read into cache" : 0,
                  "overflow values cached in memory" : 0,
                  "page split during eviction deepened the tree" : 0,
                  "page written requiring lookaside records" : 0,
                  "pages currently held in the cache" : 153,
                  "pages evicted because they exceeded the in-memory maximum" : 0,
                  "pages evicted because they had chains of deleted items" : 0,
                  "pages evicted by application threads" : 0,
                  "pages queued for eviction" : 0,
                  "pages queued for urgent eviction" : 0,
                  "pages queued for urgent eviction during walk" : 0,
                  "pages read into cache" : 151,
                  "pages read into cache requiring lookaside entries" : 0,
                  "pages requested from the cache" : 3925,
                  "pages seen by eviction walk" : 0,
                  "pages selected for eviction unable to be evicted" : 0,
                  "pages walked for eviction" : 0,
                  "pages written from cache" : 24,
                  "pages written requiring in-memory restoration" : 0,
                  "percentage overhead" : 8,
                  "tracked bytes belonging to internal pages in the cache" : 251400,
                  "tracked bytes belonging to leaf pages in the cache" : 2172246,
                  "tracked dirty bytes in the cache" : 69914,
                  "tracked dirty pages in the cache" : 2,
                  "unmodified pages evicted" : 0
              },
              "connection" : {
                  "auto adjusting condition resets" : 29,
                  "auto adjusting condition wait calls" : 1712,
                  "files currently open" : 67,
                  "memory allocations" : 24297,
                  "memory frees" : 15981,
                  "memory re-allocations" : 1026,
                  "pthread mutex condition wait calls" : 4448,
                  "pthread mutex shared lock read-lock calls" : 2818,
                  "pthread mutex shared lock write-lock calls" : 524,
                  "total fsync I/Os" : 41,
                  "total read I/Os" : 1210,
                  "total write I/Os" : 63
              },
              "cursor" : {
                  "cursor create calls" : 159,
                  "cursor insert calls" : 69,
                  "cursor next calls" : 1117,
                  "cursor prev calls" : 60,
                  "cursor remove calls" : 4,
                  "cursor reset calls" : 3291,
                  "cursor restarted searches" : 0,
                  "cursor search calls" : 3751,
                  "cursor search near calls" : 4,
                  "cursor update calls" : 0,
                  "truncate calls" : 0
              },
              "data-handle" : {
                  "connection data handles currently active" : 65,
                  "connection sweep candidate became referenced" : 0,
                  "connection sweep dhandles closed" : 1,
                  "connection sweep dhandles removed from hash list" : 5,
                  "connection sweep time-of-death sets" : 67,
                  "connection sweeps" : 27,
                  "session dhandles swept" : 1,
                  "session sweep attempts" : 19
              },
              "lock" : {
                  "checkpoint lock acquisitions" : 4,
                  "checkpoint lock application thread wait time (usecs)" : 0,
                  "checkpoint lock internal thread wait time (usecs)" : 2,
                  "handle-list lock eviction thread wait time (usecs)" : 836,
                  "metadata lock acquisitions" : 4,
                  "metadata lock application thread wait time (usecs)" : 0,
                  "metadata lock internal thread wait time (usecs)" : 2,
                  "schema lock acquisitions" : 72,
                  "schema lock application thread wait time (usecs)" : 5,
                  "schema lock internal thread wait time (usecs)" : 3,
                  "table lock acquisitions" : 0,
                  "table lock application thread time waiting for the table lock (usecs)" : 0,
                  "table lock internal thread time waiting for the table lock (usecs)" : 0
              },
              "log" : {
                  "busy returns attempting to switch slots" : 0,
                  "consolidated slot closures" : 13,
                  "consolidated slot join active slot closed" : 0,
                  "consolidated slot join races" : 0,
                  "consolidated slot join transitions" : 13,
                  "consolidated slot joins" : 18,
                  "consolidated slot transitions unable to find free slot" : 0,
                  "consolidated slot unbuffered writes" : 0,
                  "log bytes of payload data" : 6073,
                  "log bytes written" : 7808,
                  "log files manually zero-filled" : 0,
                  "log flush operations" : 2675,
                  "log force write operations" : 2973,
                  "log force write operations skipped" : 2967,
                  "log records compressed" : 5,
                  "log records not compressed" : 1,
                  "log records too small to compress" : 12,
                  "log release advances write LSN" : 7,
                  "log scan operations" : 5,
                  "log scan records requiring two reads" : 0,
                  "log server thread advances write LSN" : 6,
                  "log server thread write LSN walk skipped" : 1215,
                  "log sync operations" : 13,
                  "log sync time duration (usecs)" : 439765,
                  "log sync_dir operations" : 1,
                  "log sync_dir time duration (usecs)" : 27040,
                  "log write operations" : 18,
                  "logging bytes consolidated" : 7424,
                  "maximum log file size" : 104857600,
                  "number of pre-allocated log files to create" : 2,
                  "pre-allocated log files not ready and missed" : 1,
                  "pre-allocated log files prepared" : 2,
                  "pre-allocated log files used" : 0,
                  "records processed by log scan" : 10,
                  "total in-memory size of compressed records" : 12198,
                  "total log buffer size" : 33554432,
                  "total size of compressed records" : 5262,
                  "written slots coalesced" : 0,
                  "yields waiting for previous log file close" : 0
              },
              "reconciliation" : {
                  "fast-path pages deleted" : 0,
                  "page reconciliation calls" : 24,
                  "page reconciliation calls for eviction" : 0,
                  "pages deleted" : 0,
                  "split bytes currently awaiting free" : 0,
                  "split objects currently awaiting free" : 0
              },
              "session" : {
                  "open cursor count" : 17,
                  "open session count" : 16,
                  "table alter failed calls" : 0,
                  "table alter successful calls" : 0,
                  "table alter unchanged and skipped" : 0,
                  "table compact failed calls" : 0,
                  "table compact successful calls" : 0,
                  "table create failed calls" : 0,
                  "table create successful calls" : 0,
                  "table drop failed calls" : 1,
                  "table drop successful calls" : 1,
                  "table rebalance failed calls" : 0,
                  "table rebalance successful calls" : 0,
                  "table rename failed calls" : 0,
                  "table rename successful calls" : 0,
                  "table salvage failed calls" : 0,
                  "table salvage successful calls" : 0,
                  "table truncate failed calls" : 0,
                  "table truncate successful calls" : 0,
                  "table verify failed calls" : 0,
                  "table verify successful calls" : 0
              },
              "thread-state" : {
                  "active filesystem fsync calls" : 0,
                  "active filesystem read calls" : 0,
                  "active filesystem write calls" : 0
              },
              "thread-yield" : {
                  "application thread time evicting (usecs)" : 0,
                  "application thread time waiting for cache (usecs)" : 0,
                  "page acquire busy blocked" : 0,
                  "page acquire eviction blocked" : 0,
                  "page acquire locked blocked" : 0,
                  "page acquire read blocked" : 0,
                  "page acquire time sleeping (usecs)" : 0
              },
              "transaction" : {
                  "number of named snapshots created" : 0,
                  "number of named snapshots dropped" : 0,
                  "transaction begins" : 30,
                  "transaction checkpoint currently running" : 0,
                  "transaction checkpoint generation" : 4,
                  "transaction checkpoint max time (msecs)" : 223,
                  "transaction checkpoint min time (msecs)" : 51,
                  "transaction checkpoint most recent time (msecs)" : 53,
                  "transaction checkpoint scrub dirty target" : 0,
                  "transaction checkpoint scrub time (msecs)" : 0,
                  "transaction checkpoint total time (msecs)" : 394,
                  "transaction checkpoints" : 4,
                  "transaction checkpoints skipped because database was clean" : 1,
                  "transaction failures due to cache overflow" : 0,
                  "transaction fsync calls for checkpoint after allocating the transaction ID" : 4,
                  "transaction fsync duration for checkpoint after allocating the transaction ID (usecs)" : 21078,
                  "transaction range of IDs currently pinned" : 0,
                  "transaction range of IDs currently pinned by a checkpoint" : 0,
                  "transaction range of IDs currently pinned by named snapshots" : 0,
                  "transaction sync calls" : 0,
                  "transactions committed" : 4,
                  "transactions rolled back" : 26
              },
              "concurrentTransactions" : {
                  "write" : {
                      "out" : 0,
                      "available" : 128,
                      "totalTickets" : 128
                  },
                  "read" : {
                      "out" : 0,
                      "available" : 128,
                      "totalTickets" : 128
                  }
              }
          },
          "mem" : {
              "bits" : 64,
              "resident" : 32,
              "virtual" : 2580,
              "supported" : true,
              "mapped" : 0,
              "mappedWithJournal" : 0
          },
          "metrics" : {
              "commands" : {
                  "buildInfo" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(4)
                  },
                  "distinct" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(2)
                  },
                  "dropIndexes" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(1)
                  },
                  "getLog" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(2)
                  },
                  "isMaster" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(14)
                  },
                  "listCollections" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(4)
                  },
                  "listDatabases" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(2)
                  },
                  "replSetGetStatus" : {
                      "failed" : NumberLong(2),
                      "total" : NumberLong(2)
                  },
                  "serverStatus" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(1)
                  },
                  "whatsmyuri" : {
                      "failed" : NumberLong(0),
                      "total" : NumberLong(2)
                  }
              },
              "cursor" : {
                  "timedOut" : NumberLong(0),
                  "open" : {
                      "noTimeout" : NumberLong(0),
                      "pinned" : NumberLong(0),
                      "total" : NumberLong(0)
                  }
              },
              "document" : {
                  "deleted" : NumberLong(0),
                  "inserted" : NumberLong(0),
                  "returned" : NumberLong(0),
                  "updated" : NumberLong(0)
              },
              "getLastError" : {
                  "wtime" : {
                      "num" : 0,
                      "totalMillis" : 0
                  },
                  "wtimeouts" : NumberLong(0)
              },
              "operation" : {
                  "scanAndOrder" : NumberLong(0),
                  "writeConflicts" : NumberLong(0)
              },
              "queryExecutor" : {
                  "scanned" : NumberLong(2),
                  "scannedObjects" : NumberLong(6)
              },
              "record" : {
                  "moves" : NumberLong(0)
              },
              "repl" : {
                  "executor" : {
                      "counters" : {
                          "eventCreated" : 0,
                          "eventWait" : 0,
                          "cancels" : 0,
                          "waits" : 0,
                          "scheduledNetCmd" : 0,
                          "scheduledDBWork" : 0,
                          "scheduledXclWork" : 0,
                          "scheduledWorkAt" : 0,
                          "scheduledWork" : 0,
                          "schedulingFailures" : 0
                      },
                      "queues" : {
                          "networkInProgress" : 0,
                          "dbWorkInProgress" : 0,
                          "exclusiveInProgress" : 0,
                          "sleepers" : 0,
                          "ready" : 0,
                          "free" : 0
                      },
                      "unsignaledEvents" : 0,
                      "eventWaiters" : 0,
                      "shuttingDown" : false,
                      "networkInterface" : "\nNetworkInterfaceASIO Operations' Diagnostic:\nOperation:    Count:   \nConnecting    0        \nIn Progress   0        \nSucceeded     0        \nCanceled      0        \nFailed        0        \nTimed Out     0        \n\n"
                  },
                  "apply" : {
                      "attemptsToBecomeSecondary" : NumberLong(0),
                      "batches" : {
                          "num" : 0,
                          "totalMillis" : 0
                      },
                      "ops" : NumberLong(0)
                  },
                  "buffer" : {
                      "count" : NumberLong(0),
                      "maxSizeBytes" : NumberLong(0),
                      "sizeBytes" : NumberLong(0)
                  },
                  "initialSync" : {
                      "completed" : NumberLong(0),
                      "failedAttempts" : NumberLong(0),
                      "failures" : NumberLong(0)
                  },
                  "network" : {
                      "bytes" : NumberLong(0),
                      "getmores" : {
                          "num" : 0,
                          "totalMillis" : 0
                      },
                      "ops" : NumberLong(0),
                      "readersCreated" : NumberLong(0)
                  },
                  "preload" : {
                      "docs" : {
                          "num" : 0,
                          "totalMillis" : 0
                      },
                      "indexes" : {
                          "num" : 0,
                          "totalMillis" : 0
                      }
                  }
              },
              "storage" : {
                  "freelist" : {
                      "search" : {
                          "bucketExhausted" : NumberLong(0),
                          "requests" : NumberLong(0),
                          "scanned" : NumberLong(0)
                      }
                  }
              },
              "ttl" : {
                  "deletedDocuments" : NumberLong(0),
                  "passes" : NumberLong(4)
              }
          },
          "ok" : 1
      }
      

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                • Created:
                  Updated:
                  Resolved: