MongoDB

Question 1

Atomicity _________ isolation durability

Answer 1

Consistency

Question 2

Atomicity consistency ___________ durability

Answer 2

Isolation

Question 3

____________ consistency isolation durability

Answer 3

Atomicity

Question 4

Atomicity consistency isolation ____________

Answer 4

Durability

Question 5

ACID

Answer 5

Atomicity consistency isolation durability

Question 6

.explain() Verbosity levels

Answer 6

queryPlanner
executionStats
allPlansExecution

Question 7

____________
executionStats
allPlansExecution

Answer 7

queryPlanner

Question 8

queryPlanner
_______________
allPlansExecution

Answer 8

executionStats

Question 9

queryPlanner
executionStats
________________

Answer 9

allPlansExecution

Question 10

Create index in background

Answer 10

{background:true}

Question 11

Create text index

Answer 11

{field:”text”}

Question 12

Default write concern

Answer 12

w:1

Question 13

Enable sharding

Answer 13

sh.enableSharding(‘collection’)

Question 14

Shard collection

Answer 14

sh.shardCollection(‘collection’, {shard:key});

Question 15

Get shard status

Answer 15

sh.status();

Question 16

Add shard to cluster

Answer 16

sh.addShard(‘rs/server:port’);

Question 17

Create time to live TTL index

Answer 17

{expireAfterSeconds:360}

Question 18

List indexes

Answer 18

db.collection.getIndexes();

Question 19

Remove index

Answer 19

db.collection.dropIndex({index:signature});

Question 20

Add to replica set

Answer 20

rs.add(“hostname:port”);

Question 21

Shard query that hits a single shard

Answer 21

Targeted query

Question 22

Shard query that hits all nodes

Answer 22

Scatter gather or broadcast query

Question 23

Default chunk size

Answer 23

64mb

Question 24

Create hashed index

Answer 24

db.col.createIndex( { col: “hashed”});

Question 25

Components of ObjectId

Answer 25

Date Machine identifier Process ID Counter

Question 26

Aggregation pipeline stage memory limit

Answer 26

100MB

Question 27

Allow aggregation pipeline to use more than 100MB

Answer 27

{allowDiskUse:true}

Question 28

MMAPv1 concurrency level

Answer 28

Collection level locking

Question 29

WiredTiger concurrency level

Answer 29

Document level concurrency

Question 30

WiredTiger compression levels

Answer 30

Snappy and zlib

Question 31

What causes MMAPv1 document movement?

Answer 31

Document outgrows it's allocated space

Question 32

MMAPv1 document movement causes?

Answer 32

Indexes that point to file location to be updated

Question 33

Disable power of two allocation

Answer 33

Db.runCommand( { "collMod" : , "noPadding": true } ):

Question 34

MMAPv1 max file size

Answer 34

2047MB

Question 35

Manually split db.test chunk with number 3 into equal sized chunks

Answer 35

sh.splitFind("db.test", { "number": 3}):

Question 36

Split db.test AT number 3

Answer 36

sh.splitAt( "db.test", { "number": 3 });

Question 37

What causes an election

Answer 37

Initiating replica set, and primary becoming unavailable

Question 38

Rolled back data goes where?

Answer 38

Rollback/ folder in data path

Question 39

What causes rollback?

Answer 39

Data written to primary but not a secondary after primary failure

Question 40

Ensure data is written to most nodes

Answer 40

{w: "majority"}

Question 41

Ensure data is written to the journal

Answer 41

{j: true}

Question 42

What causes an election

Answer 42

Initiating replica set, and primary becoming unavailable

Question 43

Rolled back data goes where?

Answer 43

Rollback/ folder in data path

Question 44

Will update update a field to the same value?

Answer 44

No, it will skip it

Question 45

Can you update the _id field?

Answer 45

No, it is immutable

Question 46

By default, update will update how many documents?

Answer 46

1

Question 47

By default, remove will remove how many documents?

Answer 47

All of them.

Question 48

Remove just one document

Answer 48

Db.collection.remove({},{justOne:true);

Question 49

Update more than one document

Answer 49

db.collection.update({col:"cond"},{multi: true});

Question 50

Read preference choices

Answer 50

``` Primary primaryPreferred secondary secondaryPreferred nearest ```

Question 51

Find all from testData collection with nearest read preference

Answer 51

db.testData.find().readPref("nearest");