DP-420 Online Practice Questions and Answers

Correct Answer:

Box 1: Last Write Wins (LWW) (default) mode

Last Write Wins (LWW): This resolution policy, by default, uses a system-defined timestamp property. It's based on the time-synchronization clock protocol.

Box 2: Merge Procedures (custom) mode

Custom: This resolution policy is designed for application-defined semantics for reconciliation of conflicts. When you set this policy on your Azure Cosmos container, you also need to register a merge stored procedure. This procedure is

automatically invoked when conflicts are detected under a database transaction on the server. The system provides exactly once guarantee for the execution of a merge procedure as part of the commitment protocol.

Reference:

https://docs.microsoft.com/en-us/azure/cosmos-db/conflict-resolution-policies

https://docs.microsoft.com/en-us/azure/cosmos-db/sql/how-to-manage-conflicts

Correct Answer:

Box 1: Yes

The Automatic failover option allows Azure Cosmos DB to failover to the region with the highest failover priority with no user action should a region become unavailable.

Box 2: No

West Europe is used for failover. Only North Europe is writable.

To Configure multi-region set UseMultipleWriteLocations to true.

Box 3: Yes

Provisioned throughput with single write region costs $0.008/hour per 100 RU/s and provisioned throughput with multiple writable regions costs $0.016/per hour per 100 RU/s.

Reference: https://docs.microsoft.com/en-us/azure/cosmos-db/sql/how-to-multi-master https://docs.microsoft.com/en-us/azure/cosmos-db/optimize-cost-regions

Correct Answer:

Box 1: No

Four containers with 1000 RU/s each.

Box 2: No

Max 8000 RU/s for db2. 8 containers, so 1000 RU/s for each container.

Box 3: Yes

Max 8000 RU/s for db2. 8 containers, so 1000 RU/s for each container. Can very well add an additional container.

Reference:

https://docs.microsoft.com/en-us/azure/cosmos-db/plan-manage-costs

https://azure.microsoft.com/en-us/pricing/details/cosmos-db/

Correct Answer: B

Setting ConflictResolutionMode to Custom and using the default settings for the policy will not ensure that conflicts are sent to the conflict feed. You need to define a custom stored procedure using the "conflictingItems" parameter to handle conflicts properly.

Correct Answer: A

Correct Answer: D

With an upsert operation we can either insert or update an existing record at the same time.

FeedPollDelay: The time (in milliseconds) for the delay between polling a partition for new changes on the feed, after all current changes are drained. Default is 5,000 milliseconds, or 5 seconds.

Incorrect Answers:

A: checkpointInterval: When set, it defines, in milliseconds, the interval between lease checkpoints. Default is always after each Function call.

C: maxItemsPerInvocation: When set, this property sets the maximum number of items received per Function call. If operations in the monitored collection are performed through stored procedures, transaction scope is preserved when reading items from the change feed. As a result, the number of items received could be higher than the specified value so that the items changed by the same transaction are returned as part of one atomic batch.

Reference: https://docs.microsoft.com/en-us/azure/azure-functions/functions-bindings-cosmosdb-v2-trigger

Correct Answer: C

C: When triggers are registered, you can specify the operations that it can run with.

F: When executing, pre-triggers are passed in the RequestOptions object by specifying PreTriggerInclude and then passing the name of the trigger in a List object.

Reference: https://docs.microsoft.com/en-us/azure/cosmos-db/sql/how-to-use-stored-procedures-triggers-udfs

Correct Answer: DE

Explanation:

Connecting to a preferred region using the API for NoSQL

The SDKs accept an optional parameter PreferredLocations that is an ordered list of Azure regions.

The SDK will automatically send all writes to the current write region. All reads will be sent to the first available region in the preferred locations list. If the request fails, the client will fail down the list to the next region.

The SDK will only attempt to read from the regions specified in preferred locations. So, for example, if the Azure Cosmos DB account is available in four regions, but the client only specifies two read(non-write) regions within the

PreferredLocations, then no reads will be served out of the read region that is not specified in PreferredLocations. If the read regions specified in the PreferredLocations list are not available, reads will be served out of write region.

Reference: https://learn.microsoft.com/en-us/azure/cosmos-db/nosql/tutorial-global-distribution

Correct Answer: D

Reference: https://learn.microsoft.com/en-us/azure/cosmos-db/consistency-levels

Correct Answer: D

App1 queries the con-product and con-productVendor containers.

Note: Request unit is a performance currency abstracting the system resources such as CPU, IOPS, and memory that are required to perform the database operations supported by Azure Cosmos DB.

Scenario:

Develop an app named App1 that will run from all locations and query the data in account1.

Once multi-region writes are configured, maximize the performance of App1 queries against the data in account1.

Whenever there are multiple solutions for a requirement, select the solution that provides the best performance, as long as there are no additional costs associated.

Incorrect Answers:

A:

Bounded staleness relates to writes. App1 only do reads.

Note: Bounded staleness is frequently chosen by globally distributed applications that expect low write latencies but require total global order guarantee. Bounded staleness is great for applications featuring group collaboration and sharing, stock ticker, publish-subscribe/queueing etc.

Reference: https://docs.microsoft.com/en-us/azure/cosmos-db/consistency-levels