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  1. Documentation
  2. DOCS-15547

Fix example in documentation of 'showRecordId()' cursor method

      While investigating SERVER-67539, we noticed that the documentation for showRecordId() has a stale example. There is more context in SERVER-67539 but I will explain the problem here as well. This pertains to the following docs page: https://www.mongodb.com/docs/manual/reference/method/cursor.showRecordId/.

      At the bottom of the page, we have the following example:

      You can project the added field $recordId, as in the following example:

      db.collection.find( { a: 1 }, { $recordId: 1 } ).showRecordId()

      This query returns only the _id field and the $recordId field in the matching documents:

      "_id" : ObjectId("53908ccb18facd50a75bfbac"),
      "$recordId" : NumberLong(168112)
      "_id" : ObjectId("53908cd518facd50a75bfbad"),
      "$recordId" : NumberLong(168176)

      This used to be accurate, but the behavior changed in MongoDB 4.4 as part of PM-684. The server will now omit the "$recordId" field for this query:

      MongoDB Enterprise > db.c.find({}, {$recordId: 1}).showRecordId()
      { "_id" : ObjectId("62fead4bee4c4666b602252e") }
      { "_id" : ObjectId("62fead4bee4c4666b6022530") }
      { "_id" : ObjectId("62fead4cee4c4666b6022532") }

      We should either correct the example or delete it. The following query can be used instead against 4.4+ versions of the server to return results containing just the _id and $recordId fields:

      MongoDB Enterprise > db.c.find({}, {_id: 1}).showRecordId()
      { "_id" : ObjectId("62fead4bee4c4666b602252e"), "$recordId" : NumberLong(1) }
      { "_id" : ObjectId("62fead4bee4c4666b6022530"), "$recordId" : NumberLong(2) }
      { "_id" : ObjectId("62fead4cee4c4666b6022532"), "$recordId" : NumberLong(3) }

            jason.price@mongodb.com Jason Price
            david.storch@mongodb.com David Storch
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              1 year, 32 weeks, 4 days ago