-
rs.add("<hostname>")
-
replicaSetAdd("<hostname>")
-
rs.insert("<hostname>")
-
replica.add("<hostname>")
- restore
- backup
- mongobackup
- mongodump
-
db.citizens.select('WHERE age >= 21')
-
db.citizens.where('age >= 21')
-
db.citizens.find('WHERE age >= 21')
-
db.citizens.find({age: {$gte: 21}})
- data
- documents
- fields
- rows
-
getDateTime(_id)
-
_id.createDate()
-
_id.getTimestamp()
-
_id.getDateTime()
- myCursor.hasNext()
- myCursor.sort()
- myCursor.next()
- myCursor.find()
-
db.users.find({_id: 1})
-
db.users.seek({_id: 1})
-
db.users.query({_id: 1})
-
db.query.users({_id: 1})
-
--type jsonArray
-
--json
-
--type json
-
--jsonArray
- mongo
- mongod
- mongoconnect
- dbconnect
- db.customers.find({lastName: 'smith'}).explain()
- db.customers.find({lastName: 'smith'}).perf()
- db.customers.find({lastName: 'smith'}).plan()
- db.customers.find({lastName: 'smith'}).usedIndex()
Q11. Suppose your aggregation pipeline terminated with an exception referring to exceeded memory limit. What is the best way to resolve the issue?
- Set useMemory to twice amount indicated in exception.
- Switch a 64 bit instance of MongoDB.
- Increase the memory of the MongoDB server.
- Set allowDiskUse to true.
- db.deleteUser("user")
- db.removeUser("user") DEPRECATED
- db.remove("user")
- db.dropUser("user")
- once the primary has been down for 10 minutes
- once the primary reboots
- immediately
- after the administrator reboots the primary
-
--setParameter authenticationMechanisms=GSSAPI
-
--setAuthentication=GSSAPI
-
--setParam auth=K
-
--setAuth method=Kerberos
- It monitors replica set and sends email in case of failure
- It casts the tie-breaking vote in an election.
- It holds a backup copy of the database.
- It reboots the failed server.
-
db.product.group({_id: "$category", count: {$sum:1}})
-
db.product.aggregate($sum: {_id: "$category", count: {$group:1}})
-
db.product.aggregate($group: {_id: "$category", count: {$sum:1}})
-
db.product.aggregate($count: {_id: "$category", count: {$group:1}})
- take
- limit
- max
- skip
Q18. You have a collection named restaurants with the geographical information stored in the location property, how do you create a geospatial index on it?
-
db.restaurants.CreateIndex({location: "2dsphere"})
-
db.restaurants.geospatial({location: "2dsphere"})
-
db.restaurants.CreateIndex("2dsphere":"location")
-
db.restaurants.CreateIndex({geospatial: "location"})
-
db.customers.findmatch ({"jobs":"secretary"})
-
db.customers.find ({"jobs:secretary"})
-
db.customers.find ({"jobs":["secretary"]})
-
db.customers.find ({"jobs":"secretary"})
-
db.customers.find({}, {skip: 5, limit: 10})
-
db.customers.find({}.page(5).take(10))
-
db.customers.find({}).skip(5).take(10)
-
db.customers.find({}).skip(5).limit(10)
-
db.customers.createIndex({firstName, lastName})
-
db.customers.createTextIndex({firstName, lastName})
-
db.customers.createIndex({firstName: "text", lastName: "text"})
-
db.customers.createText({firstName: 1, lastName: 1})
Q22. Assuming you have customers collection with a firstName and lastName field, which is the correct MongoDB shell command to create an index on lastName, then firstName both ascending?
-
db.customers.createIndex("lastName, firstName, ASC")
-
db.customers.addIndex({lastName:"ASC", firstName: "ASC"})
-
db.customers.newIndex({lastName:1, firstName:1})
-
db.customers.createIndex({lastName:1, firstName: 1})
Q23. One of the documents in your collection has an _id based upon an older database design and you want to change it. You write an update command to find the document and replace the _id but the _id isn't changed. How should you fix the issue?
- Set the replace option to true.
- Use the replaceOne() command instead.
- You can't. Once set, the _id field cannot be changed.
- Use the updateOne() command instead.
- Calculate interest quickly.
- Accomplish nothing, since compound indexes aren't allowed in Mongo.
- Use more than one field per index.
- Combine fields in different collations.
- They do not have to use the same operators.
- You do not need to structure the database to support them.
- They autogenerate reports.
- They run faster than indexed queries.
- every 2 minutes
- every 5 seconds
- every 2 seconds
- every 10 seconds
-
db.customers.all();
-
db.find().customers();
-
db.customers.find();
-
db.customers.show();
Q28. Given a cursor named myCursor, pointing to the customers collection, how to you get basic info about it?
-
myCursor.stats()
-
myCursor.dump()
-
myCursor.info()
-
myCursor.explain()
- They speed up read access while slowing down writes.
- They secure the database from intruders.
- They speed up reads and writes.
- They speed up write access while slowing down reads.
- Latitude, longitude
- XML
- GeoJSON
- BSON
Q31. Which programming language is used to write MongoDB queries? (Alternative: In the MongoDB shell, what programming language is used to make queries?)
- Python
- JavaScript
- SQL
- TypeScript
Q32. You have two text fields in your document and you'd like both to be quickly searchable. What should you do?
- Create a text index on each field.
- MongoDB is not able to do this.
- Create a compound text index using both fields.
- Create a text index on one field and a single field index on the other.
- mongorestore
- mongoi
- upload
- mongoimport
- access the database
- be called only when the key has a single value
- access the database only to perform read operations
- not access the data
- the name field
- the ObjectId field
- the
_id
field - no field will have an index
Q36. You have a collection of thousands of students. You'd like to return the second set of 20 documents from the sorted collection. What is the proper order in which to apply the operations?
- limit, skip, sort
- sort, limit, skip
- limit, sort, skip
- sort, skip, limit
Q37. You would like the stats() command to return kilobytes instead of bytes. Which command should you run?
-
db.vehicle.stats(1024)
-
db.vehicle.stats("kilobytes")
-
db.vehicle.stats(true)
-
db.vehicle.stats("kb")
- Use the
reIndex()
command to modify the index. - Delete the original index and create a new index.
- Call the
createIndex()
command with the update option. - Use the
updateIndex()
command.
Q39. You need to delete the index you created on the description field. Which command will accomplish this?
-
db.vehicle.dropIndex("description_text")
-
db.vehicle.dropIndex({"description":"text"})
-
db.vehicle.removeIndex({"description":"text"})
-
db.vehicle.removeIndex("description_text")
Q40. You would like to know how many different categories you have. Which query will best get the job done?
-
db.vehicle.distinct("category")
-
db.vehicle.unique("category")
-
db.vehicle.distinct("category").count()
-
db.vehicle.distinct("category").length
Note: count() works with find(...) but length works with distinct
-
db.customers.add({name: "Bob"})
-
db.customers.save({name: "Bob"})
-
db.customers.create({name: "Bob"})
-
db.customers.new({name: "Bob"})
-
_id
-
_name
- ObjectId
- mongoDB is schema-less so no field is required
- data, namespace, and journal
- namespace, journal, and log
- journal, data, and database
- data, log, and journal
Q44. You'd like a set of documents to be returned in last name, ascending order. Which query will accomplish this?
-
db.persons.find().sort({lastName: -1}}
-
db.persons.find().sort({lastName: 1}}
-
db.persons.find().sort({lastName: ascending}}
-
db.persons.find().sort({lastName: $asc}}
- restore
- read/write
- dbadmin
- delete collections
-
db.customers.delete({_id: 1});
-
db.customers.drop({_id: 1});
-
db.drop.customers({_id: 1});
-
db.customers.remove({_id: 1});
-
db.customers.remove({}).indexes();
-
db.customers.remove({});
-
db.customers.drop();
-
db.customers.delete();
- primary
- arbiter
- secondary
- backup
Q49. You need to get the names of all the indexes on your current collection. What is the best way to accomplish this?
-
db.people.getName();
-
db.people.reIndex({names: 1});
-
db.people.getIndexKeys();
-
db.people.getIndexes();
Q50. You are going to do a series of updates to multiple records. You find setting the multi option of the update() command too tiresome. What should you do instead?
- Use the replaceMany() command instead
- Use the updateMulti() command instead
- Use the updateMany() command instead
- Set the global multi option to True
- quit()
- exit()
- db.shutdownServer()
- db.shutdown()
Q52. Given a customer collection which includes fields for gender and city, which aggregate pipeline shows the number of female customers in each city? (Alternative: How can you view the execution performance statistics for a query?)
-
db.members.aggregate([ {$match: {gender: "Female"}}, {$group: {_id: {city: "$city"}, number: {$sum: 1}}}, {$sort :{number: -1}}])
-
db.members.find({$match: {gender: "Female"}}, {$group: {_id: {city: "$city"}, number: {$sum: 1}}}.$sort ({number: -1})
-
db.members.find([ {$match: {gender: "Female"}}, {$group: {_id: {city: "$city"}, number: {$sum: 1}}}, {$sort :{number: -1}}])
-
db.members.aggregate([ {$match: {gender: "Female"}}, {$sort :{number: -1}}])
- wireTiger mode
- executionStats mode
- queryPlanner mode
- allPlansExecution mode
-
db.person.find({exists: 'homePhone'});
-
db.person.exists({homePhone: true});
-
db.person.find({homePhone: {$exists: true}});
-
db.person.has('homePhone');
- mongodb
- mongo-daemon
- daemon
- mongod
Q56. You have just secured your previously unsecured MongoDB server, but the server is still not requiring authentication. What is the best option?
- Restart the
mongod
process. - Issue the
secure()
command. - Issue the
mongoimport
command. - Issue the
authenticate()
command.
- MongoDB does not allow ad hoc queries; all queries require an index.
- Ad hoc queries are allowed only in the paid version.
- Ad hoc queries are allowed only through the ad hoc command.
- MongoDB allows ad hoc queries.
- allows you to do a calculation on the results
- allows you to run queries on the server
- allows you to select which fields should be in the return data
- allows you to format the results for a display
-
dropDatabase()
-
removeAll()
-
clear()
-
deleteDatabase()
-
-db=null
-
--shell-only
-
--free
-
-nodb
-
Use db.collection.set({$_id:pretty})
-
Create a second index
-
Use db.collection.format(numeric)
-
Use $_id = value
-
The oplog will be saved on one of the secondary servers.
-
The oplog is capped collection and can't run out of memory
-
The MongoDB instance will fail
-
The oplog will stop recording logging information
- mongo
- mongo-s
- shell
- mongo-shell
-
db.performance.members.aggregate([ {$match: {gender: "Female"}}, {$group: {_id:{city:"$city"}, number: {$sum: 1}}}, {$sort : {number: -1}}])
-
db.members.aggregate([ {$match: {gender: "Female"}}, {$group: {_id: {city: "$city"}, number:{$sum:1}}}, {$sort: {number:-1}}]).explain("executionStats")
-
db.members.aggregate([ {$match: {gender: "Female"}}, {$group:{_id: {city: "$city"}, number: {$sum: 1}}}, {$sort: {number: -1}}]).explain()
-
db.members.aggregate([ {$match: {gender: """Female"""}}, {$group: {_id: {city: """$city"""}, number: {$sum:1}}}, {$sort: {number: -1}}]).number()
- node 'list.js'
- exec('list.js)
- run('list.js)
- load('list.js)
- db.customers.sort({name: -1}.find({})
- db.customers.sort({name: -1})
- db.customers.find({}).sort({name: -1})
- db.customers.find({}).sort({name: 1})
Q67. Suppose you are using the mongoimport command to import personnel data and there is a unique index on the email field. What happens when there are duplicate emails in the import?
- The import command aborts without importing any records.
- The import command imports records upto but not including the record, and then aborts.
- The import command doesn't import the bad document but does import the rest.
- The import command prompts you to correct the bad record.
Q68. You have a collection with millions of documents. Each time you attempt to sort. MongoDB runs out of memory. What might help?
- Use the purge operator before the sort.
- Return the entire collection and sort on the client.
- Pass the --more-memory option.
- Create an index on the field you are sorting.
- Create a text index on the field and do a $text Query.
- Create an single field index in descending order, and do a query for the word.
- Do a $text query.
- Create a $regex on the fields, and do a $regex query.
- index
- Name
-
_id
- row number
- Create a user account.
- Register online.
- Create a data directory.
- Establish security credentials.
- as a properly formatted JSON array
- as YAML
- as plain text
- as a BSON object
- db.size()
- db.info()
- db.memory()
- db.stats()
- db.createUser({})
- db.insert({user: 1})
- db.customers.newUser({})
- db.newUser({})
- JSON (JavaScript Object Notation)
- BSON (Binary JSON)
- ORM (object relational mode)
- MBF (MongoDB binary format)
Q76. Which projection shows only the FirstName and lastName fields of a document in the customers collection?
-
db.customers.find({}, {firstName: 1, lastName: 1})
-
db.customers.find({}, {_id:0, firstName: 1, lastName: 1})
-
db.customers.find({_id: 0, year: 1, maek: 1, model: 1})
-
db.customers.find({}).project({firstName: 1, lastName: 1})
- database
- field
- no
- document