MongoDB C100DBA 問題集

質問 1：
In a sharded replicas set environment with multiple mongos servers, which of the following would decide the mongos failover?
A. mongo shell
B. individual language drivers
C. mongod
D. mongos
正解：B

質問 2：
Which of the following command inside aggregate command is used in MongoDB aggregation to filter the documents to pass only the documents that match the specified condition(s) to the next pipeline stage.
A. $group
B. $match
C. $sum
D. $aggregate
正解：B

質問 3：
Which features of relational database management systems were deliberately omitted in MongoDB and help us to obtain horizontal scalability? Check all that apply.
A. Joins
B. Multi-statement transactions
C. Authentication
正解：A,B

質問 4：
Below is a sample document of "orders" collection

A. $sort
正解：A

質問 5：
Which of the following is true about aggregation framework?
A. the aggregate command operates on a multiple collection
B. Each aggregation operator need to return atleast one of more documents as a result
C. A single aggregation framework operator can be used more than once in a query
D. Pipeline expressions are stateless except accumulator expressions used with $group operator
正解：B,C,D

質問 6：
Which of the documents below will be retrieved by the following query? Assume the documents are stored in a collection called "sample". Check all that apply.
db.sample.find( { "$or" : [ { "a" : { "$in" : [ 3, 10] > }, { "b" : { "$lt" : 2 > > ] > )
A. { \ Jd" : 10,"a" : 3, "c" : 1, "b" : 1}
B. {". Jd" : 6, "a" : 1, "c" : 1, "b" : 5}
C. {". Jd" : : 4, "a" : 5, "c" : : 0, "b" : 17}
D. {''_ _id" : 3, "a" : 4, "c" : 0, "b" : 14}
E. {". Jd" : : 1, "a" : 0, "c" : : 0, "b" : 2}
F. {". Jd" : : 2, "a" : 2, "c" : : 0, "b" : 1}
G. {''_ Jd" : 7, "a" : 8, "c" : 1, "b" : 7}
H. { ''\ Jd" : 9, "a" : 17, "c" : 1, "b" : 1}
I. {". Jd" : : 5, "a" : 3, "c" : : 0, "b" : 12}
J. {". Jd" : : 8, "a" : 11, "c" : 1, "b" : 0}
正解：A,F,H,I,J

質問 7：
What is the first task that a secondary would perform on being prompted by another secondary for an election?
A. Connect to primary to confirm its availability
B. Start the election process for primary
C. Vote for itself and then call for election
D. Vote for the first secondary so that it would become the next primary
正解：A

質問 8：
Which is the correct order (lowest to highest) in which MongoDB compares the BSON types?
A. Null, Number, Object and String
B. String, Null, Number and Object
C. Null, Number, String and Object
D. Number, Null, String and Object
正解：C