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Test your basic knowledge |
Mongo Db
Start Test
Study First
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. Javascript code. Documents can contain code as values.
BSON
code
$gt
$where
2. Command to get help docs on a specific command at the collection level.
$lt
BSON
db.runCommand({fsync:1,lock:1,async:1})
db.<col>.help([commandName]);
3. Returns the size of a document after it is converted to BSON from the JSON-like original.
$unset
binary data
Object.bsonsize({document});
$rename
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 } }
$pushAll
$unset
mongod
$ne
5. 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.
db.runCommand({fsync:1,lock:1,async:1})
batch insert
db.<collection>.insert({document});
64-bit floating point numbers
6. Query conditional allowing the selector to choose between more than one optional criteria.
db.<collection>.insert({document});
use <database name>
$size
$or
7. Greater than or equal query conditional. ex: db.<col>.find({numVal: {$gte:3}});
Update Modifiers
string
$gte
db.<collection>.findOne([properties]);
8. 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 } }
$set
$elemMatch
$pop
show collections
9. 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.
$in
db.myCollection.ensureIndex({keypattern},[{options}])
db.copyDatabase(frmDBName, toDBName, [frmHostName], [user], [pwd]);
64-bit floating point numbers
10. Lists all the collections in the database in use.
$push
show collections
array
Upsert
11. changes the database on which you are working.
db.<col>.help([commandName]);
null
object id
use <database name>
12. Not supported by the javascript shell and are converted to 64-bit floating point numbers.
db.<collection>.find([properties]);
db.getLastError()
undefined
64-Bit Integer
13. Clone the current database (implied by 'db') from another host.
db.cloneDatabase(fromhost)
db.copyDatabase(frmDBName, toDBName, [frmHostName], [user], [pwd]);
code
$where
14. Operator allowing the partial specification of fields in an embedded document in an array.
$lte
$elemMatch
$inc
undefined
15. Not equal query conditional. ex: db.<col>.find({numVal: {$ne:3}});
$or
$not
mongo
$ne
16. Deletes documents from the collection based on the selector.
$pull
key.index
db.<col>.remove({selector});
db.<collection>.insert({document});
17. Removes all occurrences of each value in the passed in array from the field. ex: { $pullAll : { field : value_array } }
$gt
$or
$pullAll
mongo
18. The standard number representation in the javascript shell.
db.<collection>.find([properties]);
64-bit floating point numbers
$nin
undefined
19. String of arbitrary bytes.
mongod
binary data
$not
db.help([commandName]);
20. Array specific conditional allowing matching on multiple elements within an array. The operation is non strict on the sequence of the values in the passed selector array.
db.<col>.help([commandName]);
$all
db.help([commandName]);
$pushAll
21. Update modifier that set the value of a key and if the key does not exist, it will create the key. ex: db.<col>.update({selector},{"$set":{"someKey":"someValue"}});
db.cloneDatabase(fromhost)
db.<col>.remove({selector});
$set
$ne
22. Data structure used to store all other data in mongo databases.
document
db.<collection>.insert({document});
$not
null
23. 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.
Update Modifiers
show collections
db.cloneDatabase(fromhost)
$mod
24. 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.copyDatabase(frmDBName, toDBName, [frmHostName], [user], [pwd]);
db.<collection>.find([properties]);
64-bit floating point numbers
25. A document contained by a parent document. The embedded document is a value of a key in the parent document.
$in
document
Cursor
embedded document
26. Adds a document to a collection.
db.myCollection.ensureIndex({keypattern},[{options}])
db.<collection>.insert({document});
$addToSet
db.<col>.remove({selector});
27. Set or list of values.
$addToSet
$lt
undefined
array
28. Appends a value to field - if the field is an existing array. Otherwise it sets the field to the array [value] if field is not present. ex: { $push : { field : value } }
string
$push
$ne
db.copyDatabase(frmDBName, toDBName, [frmHostName], [user], [pwd]);
29. Binary-encoded serialization of mongo documents.
BSON
binary data
$mod
$lte
30. Updates all matching documents, not just the first, that match the selector.
db.runCommand({fsync:1,lock:1,async:1})
document
embedded document
Multi-updates
31. command to start the mongodb process.
object id
mongod
db.myCollection.ensureIndex({keypattern},[{options}])
array
32. Does not contain query conditional used to select documents with the field that is not in the selector list of values.
maximum value
$mod
$nin
db.help([commandName]);
33. Less than query conditional. ex: db.<col>.find({numVal: {$lt:3}});
use <database name>
$lt
$where
Multi-updates
34. Used to describe a variable as not having been initialized.
$pushAll
string
object id
undefined
35. command to start the mongo shell.
$in
mongod
mongo
$pushAll
36. Returns information about the last operation. Not necessarily error data - the return can contain things like number of records updated.
db.getLastError()
use <database name>
$size
db.help([commandName]);
37. command to start the mongodb process.
$nin
db.cloneDatabase(fromhost)
$
mongod
38. Update modifier used to increment a value. ex: {"$inc":{"counter":2}}
db.myCollection.ensureIndex({keypattern},[{options}])
$inc
$pushAll
db.commandHelp("commandName")
39. Used to represent both a null value and a nonexistent field.
$push
batch insert
null
db.copyDatabase(frmDBName, toDBName, [frmHostName], [user], [pwd]);
40. Command to list commands and descriptions of those commands in the context of the database.
mongod
help
mongod
$in
41. Removes all occurrences of a value from a field. ex: { $pull : { field : _value } }
undefined
db.cloneDatabase(fromhost)
$pull
$mod
42. Unique 12-byte ID for documents.
object id
mongod
$pull
db.<col>.update({selector},{document});
43. Operator allowing the execution of arbitrary javascript as part of the selector.
$where
db.<collection>.findOne([properties]);
minimum value
Cursor
44. Syntax used for selectors to be specific to a certain element position within an array.
key.index
mongo
boolean
object id
45. Operator used in the second argument of the find() call to specify which slice of an array to return for an array field.
db.cloneDatabase(fromhost)
$slice
$pull
db.<collection>.insert({document});
46. Deletes a given field. ex: { $unset : { field : 1} }
use <database name>
$slice
$pullAll
$unset
47. Standard javascript regular expressions. These can be stored in documents
$where
regular expression
64-Bit Integer
$inc
48. command to start the mongo shell.
embedded document
Update Modifiers
$pop
mongo
49. ...
batch insert
db.getLastError()
help
$unset
50. Not supported by the javascript shell and are converted to 64-bit floating point numbers.
32-Bit Integer
db.<col>.remove({selector});
regular expression
db.<collection>.insert({document});