- (Exam Topic 5)
What are two methods that can be used to denormalize tables in BigQuery?

1. A. 1) Split table into multiple tables; 2) Use a partitioned table
2. B. 1) Join tables into one table; 2) Use nested repeated fields
3. C. 1) Use a partitioned table; 2) Join tables into one table
4. D. 1) Use nested repeated fields; 2) Use a partitioned table

Correct Answer: B
The conventional method of denormalizing data involves simply writing a fact, along with all its dimensions, into a flat table structure. For example, if you are dealing with sales transactions, you would write each individual fact to a record, along with the accompanying dimensions such as order and customer information.
The other method for denormalizing data takes advantage of BigQuery’s native support for nested and repeated structures in JSON or Avro input data. Expressing records using nested and repeated structures can provide a more natural representation of the underlying data. In the case of the sales order, the outer part of a JSON structure would contain the order and customer information, and the inner part of the structure would contain the individual line items of the order, which would be represented as nested, repeated elements.
Reference: https://cloud.google.com/solutions/bigquery-data-warehouse#denormalizing_data

- (Exam Topic 5)
Which of the following IAM roles does your Compute Engine account require to be able to run pipeline jobs?

1. A. dataflow.worker
2. B. dataflow.compute
3. C. dataflow.developer
4. D. dataflow.viewer

Correct Answer: A
The dataflow.worker role provides the permissions necessary for a Compute Engine service account to execute work units for a Dataflow pipeline
Reference: https://cloud.google.com/dataflow/access-control

- (Exam Topic 5)
Which row keys are likely to cause a disproportionate number of reads and/or writes on a particular node in a Bigtable cluster (select 2 answers)?

1. A. A sequential numeric ID
2. B. A timestamp followed by a stock symbol
3. C. A non-sequential numeric ID
4. D. A stock symbol followed by a timestamp

Correct Answer: AB
using a timestamp as the first element of a row key can cause a variety of problems.
In brief, when a row key for a time series includes a timestamp, all of your writes will target a single node; fill
that node; and then move onto the next node in the cluster, resulting in hotspotting.
Suppose your system assigns a numeric ID to each of your application's users. You might be tempted to use the user's numeric ID as the row key for your table. However, since new users are more likely to be active users, this approach is likely to push most of your traffic to a small number of nodes. [https://cloud.google.com/bigtable/docs/schema-design]
Reference:
https://cloud.google.com/bigtable/docs/schema-design-time-series#ensure_that_your_row_key_avoids_hotspotti

- (Exam Topic 2)
Flowlogistic’s CEO wants to gain rapid insight into their customer base so his sales team can be better informed in the field. This team is not very technical, so they’ve purchased a visualization tool to simplify the creation of BigQuery reports. However, they’ve been overwhelmed by all the data in the table, and are spending a lot of money on queries trying to find the data they need. You want to solve their problem in the most cost-effective way. What should you do?

1. A. Export the data into a Google Sheet for virtualization.
2. B. Create an additional table with only the necessary columns.
3. C. Create a view on the table to present to the virtualization tool.
4. D. Create identity and access management (IAM) roles on the appropriate columns, so only they appear in a query.

Correct Answer: C

- (Exam Topic 5)
Dataproc clusters contain many configuration files. To update these files, you will need to use the --properties option. The format for the option is: file_prefix:property= .

1. A. details
2. B. value
3. C. null
4. D. id

Correct Answer: B
To make updating files and properties easy, the --properties command uses a special format to specify the configuration file and the property and value within the file that should be updated. The formatting is as follows: file_prefix:property=value.
Reference: https://cloud.google.com/dataproc/docs/concepts/cluster-properties#formatting