rs0 [direct: secondary] mydb> db['mycoll'].find({"fsType": "PageRef","page.formData.pt_title.value": "a"}).sort({ _id: -1 }).explain('executionStats');
{
  explainVersion: '1',
  queryPlanner: {
    namespace: 'mydb.mycoll',
    indexFilterSet: false,
    parsedQuery: {
      '$and': [
        { fsType: { '$eq': 'PageRef' } },
        { 'page.formData.pt_title.value': { '$eq': 'a' } }
      ]
    },
    queryHash: '2447185D',
    planCacheKey: 'E9AC766F',
    maxIndexedOrSolutionsReached: false,
    maxIndexedAndSolutionsReached: false,
    maxScansToExplodeReached: false,
    winningPlan: {
      stage: 'SORT',
      sortPattern: { _id: -1 },
      memLimit: 104857600,
      type: 'simple',
      inputStage: {
        stage: 'FETCH',
        filter: { 'page.formData.pt_title.value': { '$eq': 'a' } },
        inputStage: {
          stage: 'IXSCAN',
          keyPattern: { fsType: 1, 'page.template.uid': 1, 'page.translated': 1 },
          indexName: 'myIndex',
          isMultiKey: false,
          multiKeyPaths: {
            fsType: [],
            'page.template.uid': [],
            'page.translated': []
          },
          isUnique: false,
          isSparse: false,
          isPartial: false,
          indexVersion: 2,
          direction: 'forward',
          indexBounds: {
            fsType: [ '["PageRef", "PageRef"]' ],
            'page.template.uid': [ '[MinKey, MaxKey]' ],
            'page.translated': [ '[MinKey, MaxKey]' ]
          }
        }
      }
    },
    rejectedPlans: [
      {
        stage: 'FETCH',
        filter: {
          '$and': [
            { fsType: { '$eq': 'PageRef' } },
            { 'page.formData.pt_title.value': { '$eq': 'a' } }
          ]
        },
        inputStage: {
          stage: 'IXSCAN',
          keyPattern: { _id: 1 },
          indexName: '_id_',
          isMultiKey: false,
          isUnique: true,
          isSparse: false,
          isPartial: false,
          indexVersion: 2,
          direction: 'backward',
          indexBounds: { _id: [ '[MaxKey, MinKey]' ] }
        }
      }
    ]
  },
  executionStats: {
    executionSuccess: true,
    nReturned: 0,
    executionTimeMillis: 1678,
    totalKeysExamined: 21489,
    totalDocsExamined: 21489,
    executionStages: {
      stage: 'SORT',
      nReturned: 0,
      executionTimeMillisEstimate: 70,
      works: 21492,
      advanced: 0,
      needTime: 21490,
      needYield: 0,
      saveState: 237,
      restoreState: 237,
      isEOF: 1,
      sortPattern: { _id: -1 },
      memLimit: 104857600,
      type: 'simple',
      totalDataSizeSorted: 0,
      usedDisk: false,
      spills: 0,
      spilledDataStorageSize: 0,
      inputStage: {
        stage: 'FETCH',
        filter: { 'page.formData.pt_title.value': { '$eq': 'a' } },
        nReturned: 0,
        executionTimeMillisEstimate: 65,
        works: 21490,
        advanced: 0,
        needTime: 21489,
        needYield: 0,
        saveState: 237,
        restoreState: 237,
        isEOF: 1,
        docsExamined: 21489,
        alreadyHasObj: 0,
        inputStage: {
          stage: 'IXSCAN',
          nReturned: 21489,
          executionTimeMillisEstimate: 9,
          works: 21490,
          advanced: 21489,
          needTime: 0,
          needYield: 0,
          saveState: 237,
          restoreState: 237,
          isEOF: 1,
          keyPattern: { fsType: 1, 'page.template.uid': 1, 'page.translated': 1 },
          indexName: 'myIndex',
          isMultiKey: false,
          multiKeyPaths: {
            fsType: [],
            'page.template.uid': [],
            'page.translated': []
          },
          isUnique: false,
          isSparse: false,
          isPartial: false,
          indexVersion: 2,
          direction: 'forward',
          indexBounds: {
            fsType: [ '["PageRef", "PageRef"]' ],
            'page.template.uid': [ '[MinKey, MaxKey]' ],
            'page.translated': [ '[MinKey, MaxKey]' ]
          },
          keysExamined: 21489,
          seeks: 1,
          dupsTested: 0,
          dupsDropped: 0
        }
      }
    }
  },
  command: {
    find: 'mycoll',
    filter: { fsType: 'PageRef', 'page.formData.pt_title.value': 'a' },
    sort: { _id: -1 },
    '$db': 'mydb'
  },
  serverInfo: {
    host: 'mongo-0',
    port: 27017,
    version: '7.0.2',
    gitVersion: '02b3c655e1302209ef046da6ba3ef6749dd0b62a'
  },
  serverParameters: {
    internalQueryFacetBufferSizeBytes: 104857600,
    internalQueryFacetMaxOutputDocSizeBytes: 104857600,
    internalLookupStageIntermediateDocumentMaxSizeBytes: 104857600,
    internalDocumentSourceGroupMaxMemoryBytes: 104857600,
    internalQueryMaxBlockingSortMemoryUsageBytes: 104857600,
    internalQueryProhibitBlockingMergeOnMongoS: 0,
    internalQueryMaxAddToSetBytes: 104857600,
    internalDocumentSourceSetWindowFieldsMaxMemoryBytes: 104857600,
    internalQueryFrameworkControl: 'forceClassicEngine'
  },
  ok: 1,
  operationTime: Timestamp({ t: 1697465159, i: 30 })
}
rs0 [direct: secondary] mydb>