C100DEV 無料問題集「MongoDB Certified Developer Associate」

（A）It's an ordered collection of keys (fields) with assigned values. The keys in each document are strings of characters. Documents in MongoDB cannot contain duplicate keys.

（B）It's a table that contains information about all collections in the database.

（C）It's a text file containing the configuration of the MongoDB instance.

（A）We can link to a single document in another collection.

（B）We can embed fields in the document.

（C）We can embed fields as a child document in the document.

（A）[{ $match: { genres: { $nin: ['Drama'] }, 'imdb.votes': { $gte: 100 } } }]

（B）[{ $match: { genres: { $in: ['Drama'] } } }, { $project: { _id: 0, title: 1, genres: 1, 'imdb.votes': 1 } }]

（C）[{ $match: { genres: { $in: ['Drama'] }, 'imdb.votes': { $gte: 100 } } }, { $project: { _id: 0, title: 1, genres: 1, 'imdb.votes': 1 } }]

（D）[{ $project: { _id: 0, title: 1, genres: 1, 'imdb.votes': 1 } }]

（A）{ rating: 1, date: 1, votes: 1 }

（B）{ date: 1, votes: 1, rating: 1 }

（C）{ date: 1, rating: 1, votes: 1 }

（D）{ votes: 1, rating: 1, date: 1 }

（E）{ rating: 1, votes: 1, date: 1 }

（F）{ votes: 1, date: 1, rating: 1 }

（A）Replication is the primary mechanism for providing high availability in MongoDB.

（B）The primary node receives all new write operations, and the secondary nodes stay up to date with the primary.

（C）In the event of failover, the nodes vote to select the new primary node.

（A）The Polymorphic Pattern.

（B）The Schema Versioning Pattern.

（C）The Outlier Pattern.

（D）The Subset Pattern.

（E）The Attribute Pattern.

（A）secondaryPreferred

（B）primary

（C）secondary

（D）primaryPreferred

（E）nearest

（A）Replica set members have a fixed role assigned.

（B）Replica sets use failover to provide high availability to client applications.

（C）We can have up to 50 replica set members, but only 7 of those will be voting members.

（A）Query plans are cached so that plans don't have to be generated and compared with each other each time a query is executed.

（B）If there are no indexes for the query, the main stage in the query plan will be the COLLSCAN stage.

（C）For a given query, each index in the collection generates at least one query plan.

（A）In the primary shard.

（B）On the configuration servers.

（C）In a random shard.

（A）You need to apply document validation before inserting/modifying.

（B）Some fields share a similar characteristics, and you want to search across those fields.

（C）The documents in the collection are quite large.