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Mongo Db

Subject : it-skills

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. Special keys passed in an update call to specify complex update operations - such as alter - adding - or removing keys - and even manipulating arrays and embedded documents.
$gt
db.commandHelp("commandName")
Update Modifiers
$pullAll

2. Not supported by the javascript shell and are converted to 64-bit floating point numbers.
$mod
$addToSet
32-Bit Integer
use <database name>

3. Update modifier used to increment a value. ex: {"$inc":{"counter":2}}
$inc
$set
Upsert
regular expression

4. Appends each value in the value_array to the field - if field is an existing array. Otherwise - it sets the field to the array value_array - if field is not present ex: { $pushAll : { field : value_array } }
db.myCollection.ensureIndex({keypattern},[{options}])
db.<collection>.find([properties]);
$pushAll
use <database name>

5. Adds a value to the array only if its not in the array already. Otherwise, if the field is not present, it sets the field to the array value. ex: { $addToSet : { a : { $each : [ 3 , 5 , 6 ] } } }
$
$addToSet
db.<col>.remove({selector});
$slice

6. Binary-encoded serialization of mongo documents.
$lt
$
regular expression
BSON

7. Unique 12-byte ID for documents.
object id
BSON
db.cloneDatabase(fromhost)
db.<col>.remove({selector});

8. Command to get help docs on a specific command at the collection level.
$elemMatch
$size
mongo
db.<col>.help([commandName]);

9. Meta query conditional used to negate the selector.
$ne
mongod
$not
$or

10. command to start the mongo shell.
mongod
mongo
Upsert
db.<collection>.findOne([properties]);

11. Query conditional allowing the selector to choose between more than one optional criteria.
$gt
$or
Cursor
db.<col>.remove({selector});

12. A document contained by a parent document. The embedded document is a value of a key in the parent document.
$rename
embedded document
$lt
db.<col>.update({selector},{document});

13. Operator allowing the execution of arbitrary javascript as part of the selector.
$pop
$nin
$gt
$where

14. String of arbitrary bytes.
binary data
$pull
64-Bit Integer
$inc

15. Stored as milliseconds since the epoch.
date
array
$gte
$pop

16. The local variable representation of a query. Uniquely - the cursor does not hold the results but instead access to the results.
db.runCommand({fsync:1,lock:1,async:1})
Cursor
$slice
use <database name>

17. Does not contain query conditional used to select documents with the field that is not in the selector list of values.
$addToSet
show collections
db.copyDatabase(frmDBName, toDBName, [frmHostName], [user], [pwd]);
$nin

18. Meta query conditional generating a modulus with the selector operand. Checks to see if the field value when divided by one value has the remainder of the second value.
db.copyDatabase(frmDBName, toDBName, [frmHostName], [user], [pwd]);
db.cloneDatabase(fromhost)
64-Bit Integer
$mod

19. Removes all occurrences of a value from a field. ex: { $pull : { field : _value } }
db.cloneDatabase(fromhost)
$pull
db.help([commandName]);
array

20. Greater than query conditional. ex: db.<col>.find({numVal: {$gt:3}});
$pushAll
$rename
Cursor
$gt

21. Flushes all pending writes to data files. The lock option allows one to safely snapshot the database's data files. The async option returns focus to the console immediately while the task runs in the background.
mongod
64-Bit Integer
db.runCommand({fsync:1,lock:1,async:1})
db.cloneDatabase(fromhost)

22. Adds a document to a collection.
db.<collection>.insert({document});
64-Bit Integer
regular expression
$or

23. Copies an entire database from one name on one server to another name on another server. Omit frmHostName to copy from one name to another on the same server.
string
db.copyDatabase(frmDBName, toDBName, [frmHostName], [user], [pwd]);
embedded document
$addToSet

24. Deletes documents from the collection based on the selector.
db.myCollection.ensureIndex({keypattern},[{options}])
64-Bit Integer
db.<col>.remove({selector});
$lte

25. ...
batch insert
array
db.<collection>.findOne([properties]);
$ne

26. Deletes a given field. ex: { $unset : { field : 1} }
$unset
mongo
$pullAll
mongo

27. Returns help information for a command.
$inc
null
db.commandHelp("commandName")
mongod

28. Lists all the collections in the database in use.
show collections
$pushAll
help
db.<col>.help([commandName]);

29. Clone the current database (implied by 'db') from another host.
db.<collection>.find([properties]);
$in
show collections
db.cloneDatabase(fromhost)

30. Adds a document to a collection.
regular expression
db.<collection>.insert({document});
$rename
Update Modifiers

31. Used to represent both a null value and a nonexistent field.
Upsert
db.commandHelp("commandName")
boolean
null

32. Update call that inserts a new document if no update match is found. Allows the same code to be used for inserts as well as updates.
document
$lt
$set
Upsert

33. Less than or equal query conditional. ex: db.<col>.find({numVal: {$lte:3}});
$inc
$lt
$lte
$push

34. command to start the mongodb process.
Cursor
mongo
db.runCommand({fsync:1,lock:1,async:1})
mongod

35. Creates an index on property(s). Options can describe the type of sorting, uniqueness, etc.
$mod
$or
db.commandHelp("commandName")
db.myCollection.ensureIndex({keypattern},[{options}])

36. Removes an element from an array based on the value of the field option being 1 or -1 for last or first element respectively. ex: { $pop : { field : -1 } }
db.getLastError()
$pop
db.<col>.help([commandName]);
mongod

37. Renames a field from the one indicated to the new field name. ex: { $rename : { old_field_name : new_field_name } }
$rename
$
null
minimum value

38. Set or list of values.
db.myCollection.ensureIndex({keypattern},[{options}])
$size
array
$pushAll

39. changes the database on which you are working.
$all
use <database name>
db.<collection>.insert({document});
Cursor

40. Not equal query conditional. ex: db.<col>.find({numVal: {$ne:3}});
minimum value
$ne
db.getLastError()
$gt

41. In BSON - represents the smallest possible value.
db.help([commandName]);
mongod
minimum value
Update Modifiers

42. Update modifier that set the value of a key and if the key does not exist, it will create the key. ex: db.<col>.update({selector},{"$set":{"someKey":"someValue"}});
$gt
Multi-updates
$mod
$set

43. Update a document in the collection.
db.cloneDatabase(fromhost)
64-Bit Integer
Upsert
db.<col>.update({selector},{document});

44. Command to get help docs on a specific command at the db level.
mongod
$inc
db.help([commandName]);
BSON

45. The standard number representation in the javascript shell.
64-bit floating point numbers
key.index
db.<collection>.find([properties]);
date

46. Javascript code. Documents can contain code as values.
code
db.<collection>.insert({document});
db.getLastError()
document

47. Removes all occurrences of each value in the passed in array from the field. ex: { $pullAll : { field : value_array } }
$pullAll
undefined
mongo
db.myCollection.ensureIndex({keypattern},[{options}])

48. Operator used in the second argument of the find() call to specify which slice of an array to return for an array field.
$
$slice
date
db.<collection>.insert({document});

49. Returns information about the last operation. Not necessarily error data - the return can contain things like number of records updated.
$nin
Cursor
64-bit floating point numbers
db.getLastError()

50. Contains query conditional used to check if a value contains the field value.
$unset
db.<col>.help([commandName]);
$
$in