Dynamo DB

Question 1

Is DynamoDB single region?

Answer 1

No

Question 2

Does it support SQL?

Answer 2

No

Question 3

What consistency model DynamoDB supports by default?

Answer 3

Eventual consistency

Question 4

What consistency model DynamoDB supports?

Answer 4

Eventual (default) and strong consistency

Question 5

What is disadvantage of strongly consistent read?

Answer 5

It may fail if data is not available.

Question 6

What ACID consistency stands for?

Answer 6

Atomic Consistent Isolated Durable

Question 7

What BASE consistency stands for?

Answer 7

Basic Availability, Soft-state, Eventual-consistency

Question 8

What DynamoDB price model is based on?

Answer 8

The pricing is based on throughput. User should define how may reads/writes is needed per minute.

Question 9

How Autoscale works with DynamoDB?

Answer 9

Auto scaling rules scale up based on throughput. Scaling down is tricky process.

Question 10

What is On-Demand complicity

Answer 10

When you do not know upfront read/write capacity DynamoDB will automatically determine needed capacity. It is cheaper to go with Auto-scale, provisioning through put upfront.

Question 11

How to achieve ACID compliance?

Answer 11

By using DynamoDB transactions.

Question 12

How DynamoDB identifies a document?

Answer 12

1. By using partition key that are use to calculate hash. The hash is used to identify a partition where data is
   located.
2. By using partition key and sort key. Partition key defines a partition. sort index determines sort order with in a partition.

Question 13

What is Global Secondary Index

Answer 13

Partition key and sort key can be different from those on the table. Global means that it is not restricted for a partition data is stored in…

Question 14

What is Local Secondary Index

Answer 14

Same partition key as in a table but sort key may be different.

Question 15

What is the limit for amount of secondary indexes?

Answer 15

No limit. But indexes take up a storage space.

Question 16

What is the use case for GLOBAL Secondary Index?

Answer 16

Fast query attributes by index outside of primary key.

Question 17

What is the use case to use LOCAL secondary index?

Answer 17

When you know primary key and want to get by other sort key.

Question 18

What is projection?

Answer 18

Projection is required to create a secondary index. Projections are stored in separate tables. The table attributes are copied to these storage. Projections always occur with [partition key]+[sort index].

Question 19

Keep cost down, and minimal latency to access just a few attributes the faster way possible?

Answer 19

Projecting just those attributes in GLOBAL Secondary Index. It will keep cost MINIMAL, and will give lowest possible latency for those fields.

Question 20

Keep cost moderate and lowest latency when FREQUENTLY access some-non key attributes.

Answer 20

Projecting those attributes with global secondary index. It will minimize cost otherwise caused by scans.

Question 21

What to do in order to frequently query all attributes?

Answer 21

Projecting it or even entire table with secondary index will double the price (basically it is maintaining a duplicate table). But it gives maximum flexibility querying the table.

Question 22

What to do to rarely query but write or update frequently?

Answer 22

Project keys only for global secondary index.

Minimal cost. Fast writes or updates for non-partition items