DP-420 Online Practice Questions and Answers

Correct Answer:

Box 1: CompanyID After you create a container with a unique key policy, the creation of a new or an update of an existing item resulting in a duplicate within a logical partition is prevented, as specified by the unique key constraint. The partition key combined with the unique key guarantees the uniqueness of an item within the scope of the container.

For example, consider an Azure Cosmos container with Email address as the unique key constraint and CompanyID as the partition key. When you configure the user's email address with a unique key, each item has a unique email address within a given CompanyID. Two items can't be created with duplicate email addresses and with the same partition key value.

Box 2: emailAddress

Reference: https://docs.microsoft.com/en-us/azure/cosmos-db/unique-keys

Correct Answer:

Box 1: Yes

Need to join readings and devices.

Box 2: No

Only readings is required. All required fields are in readings.

Box 3: No

Only devices is required. All required fields are in devices.

Correct Answer: B

Based on the characteristics of the application and the provided document structure, the most suitable partition key value for coll1 in the given scenario would be the customerId, Option B. The application frequently creates new orders by different customers and customers often view their past order history. Using customerId as the partition key would ensure that all orders associated with a particular customer are stored in the same partition. This enables efficient querying of past order history for a specific customer and reduces cross-partition queries, resulting in lower costs and improved performance. a partition key is a JSON property (or path) within your documents that is used by Azure Cosmos DB to distribute data among multiple partitions3. A partition key should have a high cardinality, which means it should have many distinct values, such as hundreds or thousands1. A partition key should also align with the most common query patterns of your application, so that you can efficiently retrieve data by using the partition key value1. Based on these criteria, one possible partition key that you could use for coll1 is B:customerId.

This partition key has the following advantages: It has a high cardinality, as each customer will have a unique ID3. It aligns with the query patterns of the application, as customers will often view their past order history3. It minimizes costs, as it reduces the number of cross-partition queries and optimizes the storage and throughput utilization1. This partition key also has some limitations, such as: It may not be optimal for scenarios where orders need to be queried independently from customers or aggregated by date or other criteria3. It may result in hot partitions or throttling if some customers create orders more frequently than others or have more data than others1. It may not support transactions across multiple customers, as transactions are scoped to a single logical partition2. Depending on your specific use case and requirements, you may need to adjust this partition key or choose a different one. For example, you could use a synthetic partition key that concatenates multiple properties of an item2, or you could use a partition key with a random or pre-calculated suffix to distribute the workload more evenly2.

Correct Answer: A

When creating a new Azure Cosmos DB account, in the Backup policy tab, choose continuous mode to enable the point in time restore functionality for the new account. With the point-in-time restore, data is restored to a new account, currently you can't restore to an existing account.

Reference: https://docs.microsoft.com/en-us/azure/cosmos-db/provision-account-continuous-backup

Correct Answer: A

If a query has a filter with two or more properties, adding a composite index will improve performance.

Consider the following query:

SELECT * FROM c WHERE c.name = “Tim” and c.age > 18

In the absence of a composite index on (name ASC, and age ASC), we will utilize a range index for this query. We can improve the efficiency of this query by creating a composite index for name and age.

Queries with multiple equality filters and a maximum of one range filter (such as >,<, <=, >=, !=) will utilize the composite index.

Reference:

https://azure.microsoft.com/en-us/blog/three-ways-to-leverage-composite-indexes-in-azure-cosmos-db/

Correct Answer: A

IS_NUMBER returns a Boolean value indicating if the type of the specified expression is a number. "1234" is a string, not a number.

Reference: https://docs.microsoft.com/en-us/azure/cosmos-db/sql/sql-query-is-number

Correct Answer: B

Explanation:

Instead configure an Azure Monitor alert to trigger the function.

You can set up alerts from the Azure Cosmos DB pane or the Azure Monitor service in the Azure portal.

Reference:

https://docs.microsoft.com/en-us/azure/cosmos-db/create-alerts

Correct Answer: D

Explanation:

Time to live for containers and items

The time to live value is set in seconds, and it is interpreted as a delta from the time that an item was last modified. You can set time to live on a container or an item within the container:

Time to Live on a container (set using DefaultTimeToLive):

If missing (or set to null), items are not expired automatically.

If present and the value is set to "-1", it is equal to infinity, and items don't expire by default.

If present and the value is set to some non-zero number "n" – items will expire "n" seconds after their last modified time.

Reference:

https://learn.microsoft.com/en-us/azure/cosmos-db/nosql/time-to-live

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

Correct Answer: C

Scenario: Develop an app named App2 that will run from the retail stores and query the data in account2. App2 must be limited to a single DNS endpoint when accessing account2.

By using Azure Private Link, you can connect to an Azure Cosmos account via a private endpoint. The private endpoint is a set of private IP addresses in a subnet within your virtual network.

When you're using Private Link with an Azure Cosmos account through a direct mode connection, you can use only the TCP protocol. The HTTP protocol is not currently supported.

Reference:

https://docs.microsoft.com/en-us/azure/cosmos-db/how-to-configure-private-endpoints