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Questions # 21:

What are the benefits of creating indexes on PolarDB? (Number of correct answers: 2)

Options:
A.

Improve the query efficiency SELECT statements.

B.

Improve the efficiency of DML operations such as UPDATE.

C.

Improve the efficiency of DDL operations.

D.

Reduce invalid data scanning.

Expert Solution
Questions # 22:

Which of the following statements about migrating data into and out of Object Storage Service (OSS) are correct? (Number of correct answers: 3)

Options:
A.

You can migrate data between OSS buckets in any of the following conditions: Buckets are located within the same region, buckets are located across regions and buckets belong to different Alibaba Cloud accounts.

B.

A migration job occupies the network resources of the source and the destination. To ensure business continuity, we recommend that you specify a rate limit for a migration Job or run the migration job during an off-peak period.

C.

You cannot migrate data between OSS buckets if the data at the source is stored in a bucket of the Archive type.

D.

Online migration supports both migrating buckets at a time, and migrating all the data under an Alibaba Cloud account at a single time.

Expert Solution
Questions # 23:

In PolarDB, if an UPDATE SQL statement encounters an issue, you need to check the execution plan to figure out the root cause. However, in the production environment, to avoid affecting the production data, what statement should you use to view the execution plan? (Number of correct answers: 2)

Options:
A.

explain SQL

B.

explain analyze SQL

C.

explain verbose SQL

D.

explain analyze verbose SQL

Expert Solution
Questions # 24:

When connecting to the Alibaba Cloud RDS database, in order to improve the completeness and integrity of the connection, you can enable SSL encryption and install an SSL CA certificate for the required application service. Which of the following statements are correct? (Number of correct answers: 3)

Options:
A.

Due to the way in which SSL encryption is implemented, enabling SSL encryption will significantly increase the CPU usage rate. Enable SSL encryption when there is an encryption requirement for the external network link. The intranet link is relatively safe, and generally no link encryption is required.

B.

If the RDS instance is a multi-node instance, the system will trigger the active/standby switch after the SSL service is disabled.

C.

When using read/write splitting, you can also enable SSL encryption to improve the security of the connection.

D.

It is discovered that an Alibaba Cloud RDS SSL certificate is about to expire, and the validity period needs to be updated, requiring that the certificate be updated, then reinstalled. This will restart the RDS instance.

Expert Solution
Questions # 25:

Which of the following is NOT a feature of Alibaba Cloud's Cassandra database service?

Options:
A.

Centerless distributed architecture

B.

Supports both narrow and wide tables, providing flexible schema functions

C.

Cluster storage, strong expansion of read and write capabilities

D.

Enterprise-level capabilities such as disaster tolerance, backup and recovery, security, and monitoring across data centers

Expert Solution
Questions # 26:

A job hunting website stores user's resumes in Object Storage Service (OSS) The current resume upload process is as follows:

7. Users upload resumes

2. The server responds to the upload request

3. The resume is uploaded to the server

4. 1 he server uploads the resume to OSS

Which of the following methods can be used to upload objects to OSS without requiring Step 3?

Options:
A.

Simple Upload

B.

Form Upload

C.

Multipart Upload

D.

Append Upload

Expert Solution
Questions # 27:

Which of the following statements about PolarDB's endpoint(s) is NOT correct?

Options:
A.

The endpoint of the PolarDB MySQL database includes the cluster endpoint and the primary endpoint.

B.

Through a cluster endpoint, applications can connect to data nodes.

C.

The primary endpoint supports read/write splitting.

D.

Cluster endpoints support read/write splitting.

Expert Solution
Questions # 28:

When you use SQL statements to access tables in a database without an index configured, a full table scan will be performed. If a table contains a large amount of data, this kind of scan will access a large amount of data and consume a lot of the database's resources. Which of the following options are best practices when creating database indexes? (Number of correct answers: 3)

Options:
A.

Add an index to a field that is frequently queried but does not frequently perform add, delete, or modify operations.

B.

Applies indices to fields that contain many records.

C.

table should not contain more than 6 indexed fields.

D.

Apply indexing to fields of fixed length (preferably not long fields).

E.

Adhere to the rightmost prefix principle when using composite indexes.

Expert Solution
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