Authentic Snowflake Certification Exam ARA-C01 Questions Answers

To create a read-only role for certain employees working in the human resources department, the role needs to have the following permissions on the hr_db database:

USAGE on the database: This allows the role to access the database and see its schemas and objects.

USAGE on all schemas in the database: This allows the role to access the schemas and see their objects.

SELECT on all tables in the database: This allows the role to query the data in the tables.

Option A is the correct answer because it grants the minimum permissions required for a read-only role on the hr_db database.

Option B is incorrect because SELECT on schemas is not a valid permission. Schemas only support USAGE and CREATE permissions.

Option C is incorrect because MODIFY on the database is not a valid permission. Databases only support USAGE, CREATE, MONITOR, and OWNERSHIP permissions. Moreover, USAGE on tables is not sufficient for querying the data. Tables support SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, and OWNERSHIP permissions.

Option D is incorrect because REFERENCES on tables is not relevant for querying the data. REFERENCES permission allows the role to create foreign key constraints on the tables.

https://docs.snowflake.com/en/user-guide/security-access-control-privileges.html#database-privileges

https://docs.snowflake.com/en/user-guide/security-access-control-privileges.html#schema-privileges

https://docs.snowflake.com/en/user-guide/security-access-control-privileges.html#table-privileges

 Compilation time is the time it takes for the optimizer to create an optimal query plan for the efficient execution of the query. It also involves some pruning of partition files, making the query execution efficient2

If the compilation time is greater than the execution time, it means that the optimizer spent more time analyzing the query than actually running it. This could indicate that the query has overly complex logic, such as multiple joins, subqueries, aggregations, or expressions. The complexity of the query could also affect the size and quality of the query plan, which could impact the performance of the query3

To reduce the compilation time, the Architect can try to simplify the query logic, use views or common table expressions (CTEs) to break down the query into smaller parts, or use hints to guide the optimizer. The Architect can also use the EXPLAIN command to examine the query plan and identify potential bottlenecks or inefficiencies4 References:

1: SnowPro Advanced: Architect | Study Guide 5

2: Snowflake Documentation | Query Profile Overview 6

3: Understanding Why Compilation Time in Snowflake Can Be Higher than Execution Time 7

4: Snowflake Documentation | Optimizing Query Performance 8

: SnowPro Advanced: Architect | Study Guide

: Query Profile Overview

: Understanding Why Compilation Time in Snowflake Can Be Higher than Execution Time

: Optimizing Query Performance

 According to the Snowflake documentation, the best practices for choosing clustering keys are:

Choose columns that are frequently used in join predicates. This can improve the join performance by reducing the number of micro-partitions that need to be scanned and joined.

Choose columns that are most actively used in selective filters. This can improve the scan efficiency by skipping micro-partitions that do not match the filter predicates.

Avoid using low cardinality columns, such as gender or country, as clustering keys. This can result in poor clustering and high maintenance costs.

Avoid using TIMESTAMP columns with nanoseconds, as they tend to have very high cardinality and low correlation with other columns. This can also result in poor clustering and high maintenance costs.

Avoid using columns with duplicate values or NULLs, as they can cause skew in the clustering and reduce the benefits of pruning.

Cluster on multiple columns if the queries use multiple filters or join predicates. This can increase the chances of pruning more micro-partitions and improve the compression ratio.

Clustering is not always useful, especially for small or medium-sized tables, or tables that are not frequently queried or updated. Clustering can incur additional costs for initially clustering the data and maintaining the clustering over time.

Clustering Keys & Clustered Tables | Snowflake Documentation

[Considerations for Choosing Clustering for a Table | Snowflake Documentation]