CosmosDB

Question 1

Considerations for choosing partition key

Answer 1

• transactions can only occur across a single partition
• queries work fastest when not run across all partitions
• containers can contain 1 or more partitions

Question 2

What is the property to run a query across partitions?

Answer 2

EnableCrossPartitionQuery

Question 3

What is the property to run a query in parallel?

Answer 3

MaxDegreeOfParallelism (client side)

Question 4

Strong Consistency

Answer 4

1. Guarantees no dirty reads

High latency because must wait for all slaves to update

Question 5

Eventual Consistency

Answer 5

5. There’s no ordering guarantee for reads. In the absence of any further writes, the replicas eventually converge.

Low latency because only one write to make

Question 6

Bounded Staleness Consistency

Answer 6

2. Dirty reads possible

Staleness configurable by time and updates (i.e. no stale data older than 30 seconds)

Question 7

Session Consistency

Answer 7

3. No dirty reads for the writer (read your own writes)

Scoped to a client session.

Dirty reads possible for the other users

Question 8

Consistent Prefix Consistency

Answer 8

4. Updates that are returned contain some prefix of all the updates, with no gaps.

Consistent prefix guarantees that reads never see out-of-order writes.

Question 9

What is the _etag property?

Answer 9

GUID used for optimistic concurrency so Cosmos knows when one user is going to override changes of another user resulting in a conflict

Question 10

Hash Index

Answer 10

Used for equality queries for strings and numbers.

Question 11

Range Index

Answer 11

Equality range, order by for strings and numbers.

Question 12

Spatial Index

Answer 12

Distance and intersection for geo coordinates

Question 13

Consistent Indexing Mode

Answer 13

Indexed as soon as the document is added or updated.

Question 14

Lazy Indexing Mode

Answer 14

Indexed when Cosmos has CPU cycles to spare and is not processing requests.