DynamoDB

Question 1

What type of database is DynamoDB?

Answer 1

NoSQL, non-relational, fully managed, highly available, horizontally scalable

Question 2

What is the maximum item size in DynamoDB?

Answer 2

400KB including all attribute names and values

Question 3

What are the data types supported by DynamoDB?

Answer 3

Scalar (String, Number, Binary), Document (List, Map), Set (String Set, Number Set, Binary Set)

Question 4

What is a Partition Key?

Answer 4

Primary key that must be unique for each item and ensures data distribution

Question 5

What is a Sort Key?

Answer 5

Used with Partition Key for composite primary keys, allows grouping and sorting

Question 6

What are RCU and WCU in DynamoDB?

Answer 6

RCU = 1 strong read/sec for 4KB or 2 eventual, WCU = 1 write/sec for 1KB

Question 7

What are the two read/write capacity modes in DynamoDB?

Answer 7

Provisioned and On-Demand

Question 8

What causes ‘ProvisionedThroughputExceededException’?

Answer 8

Exceeding provisioned RCUs/WCUs or hot partition keys

Question 9

What DynamoDB feature can reduce hot key issues?

Answer 9

DAX (DynamoDB Accelerator)

Question 10

What operation reads items by Primary Key?

Answer 10

GetItem

Question 11

What operation is used to retrieve multiple items with the same partition key?

Answer 11

Query

Question 12

What operation scans the whole table?

Answer 12

Scan

Question 13

What is the difference between Query and Scan?

Answer 13

Query is efficient and uses keys, Scan reads the entire table

Question 14

What are DynamoDB Streams?

Answer 14

Ordered stream of item-level changes in a table

Question 15

What can consume DynamoDB Streams?

Answer 15

Lambda, Kinesis, KCL Apps

Question 16

What is TTL in DynamoDB and what happens when items expire?

Answer 16

Auto-deletes items after Unix timestamp. Items may briefly appear in reads before deletion.

Question 17

What is a Local Secondary Index (LSI)?

Answer 17

Alternate sort key, same partition key, up to 5 per table, defined at table creation

Question 18

What is a Global Secondary Index (GSI)?

Answer 18

Alternate primary key, can be added anytime, requires separate RCUs/WCUs

Question 19

What happens if a GSI is throttled?

Answer 19

Writes to the base table may also be throttled

Question 20

What is the SQL-compatible query language for DynamoDB?

Answer 20

PartiQL

Question 21

What are Conditional Writes in DynamoDB?

Answer 21

Write operations that only succeed if conditions are met (e.g. attribute_not_exists)

Question 22

What does ‘attribute_not_exists’ help with?

Answer 22

Prevents overwriting existing items

Question 23

What are DynamoDB Transactions?

Answer 23

ACID complaint Atomicity, Consistency, Isolation, Durability. Enable coordinated, all or nothing operations on one or more items across one or more tables in DynamoDb.

Question 24

What is the DynamoDB CLI option to retrieve specific attributes?

Answer 24

–projection-expression

Question 25

What is DAX?

Answer 25

In-memory caching for DynamoDB with microsecond latency

Question 26

What is the default cache TTL for DAX?

Answer 26

5 minutes

Question 27

What security features does DynamoDB support?

Answer 27

IAM, KMS encryption, VPC endpoints, SSL/TLS

Question 28

What is the use of DynamoDB Streams in cross-region replication?

Answer 28

Provides real-time change data for replication

Question 29

What is the maximum retention of DynamoDB Streams?

Answer 29

24 hours

Question 30

What is Optimistic Locking in DynamoDB?

Answer 30

Uses version number to avoid conflicts during concurrent writes

Question 31

How do you manage fine-grained access control in DynamoDB?

Answer 31

IAM with conditions on LeadingKeys and attributes

Question 32

What are the TTL stream options?

Answer 32

KEYS_ONLY, NEW_IMAGE, OLD_IMAGE, NEW_AND_OLD_IMAGES

Question 33

Can you use DynamoDB without internet access?

Answer 33

Yes, using DynamoDB Local

Question 34

When should you use On-Demand mode in DynamoDB?

Answer 34

Unpredictable or spiky workloads

Question 35

What AWS service helps migrate data to DynamoDB?

Answer 35

AWS Database Migration Service (DMS)

Question 36

What is Write Sharding in DynamoDB?

Answer 36

Technique to distribute writes across partitions by adding suffixes to avoid hot partitions and throttling

Question 37

What is the Partition Key Hashing used for?

Answer 37

Determines which partition the item goes to

Question 38

How are Scan and Parallel Scan different?

Answer 38

Parallel Scan uses multiple workers to scan data segments

Question 39

What does --filter-expression do in CLI?

Answer 39

Filters items before they are returned

Question 40

What does --max-items do in CLI?

Answer 40

Limits number of items shown and returns a NextToken

Question 41

Can conditional writes be used in BatchWriteItem?

Answer 41

No, BatchWriteItem does not support condition expressions

Question 42

How does DynamoDB ensure consistency?

Answer 42

Offers Strongly Consistent Reads as an option

Question 43

What does 'Begins_with' condition do?

Answer 43

Checks if an attribute starts with a given substring

Question 44

Can you use IAM to limit attribute-level access?

Answer 44

Yes, via fine-grained access policies