AWS Certified Data Engineer - Associate (DEA-C01) Practice Tests

Explanation

The Parallel state in AWS Step Functions executes multiple explicitly defined branches concurrently, starting each branch at its designated StartAt state. The Parallel state waits until all branches reach a terminal state before transitioning to the next state in the workflow, combining their outputs. This is the correct mechanism for running independent tasks simultaneously to reduce total processing time. The Fail state terminates the execution with a failure status and provides no execution or branching capability. The Choice state evaluates conditions against input data and routes execution to one of several possible next states, but it processes only one branch at a time rather than concurrently. The Succeed state terminates the execution successfully and has no capability to manage or monitor concurrent task execution.

Explanation

AWS DataSync is purpose-built for automating and accelerating data movement between on-premises storage systems and AWS storage services including S3, supporting both one-time migrations and periodic scheduled transfers. It handles scheduling, monitoring, and data integrity verification automatically. AWS Glue is an ETL service designed for data preparation and analytics workflows, not for periodic file synchronization between on-premises and S3. AWS Storage Gateway is optimized for hybrid cloud access patterns where on-premises applications need seamless access to cloud storage, not for periodic batch replication. AWS Snowball is a physical device for large one-time data transfers and does not support automated periodic replication.

Explanation

Amazon AppFlow is a fully managed integration service built specifically to move data between SaaS applications such as Salesforce, ServiceNow, and Slack and AWS services including S3 and Redshift. It provides native connectors, built-in data transformation capabilities, and multiple trigger options without requiring custom code or pipeline infrastructure. The service handles authentication, API rate limiting, and data format normalization automatically. Amazon EventBridge is an event bus service for routing events between AWS services and applications; while it can trigger actions in response to SaaS events, it does not extract and deliver the underlying data to S3 or Redshift without additional custom development. MWAA is an orchestration service for Apache Airflow workflows that can coordinate data movement tasks but requires deploying and managing an Airflow environment, writing DAG code, and configuring SaaS connectors manually. AWS Step Functions orchestrates sequences of AWS service calls but does not include built-in SaaS connectors and would require Lambda functions and custom integration code to extract data from external applications.

Explanation

STL_ALERT_EVENT_LOG records alerts generated by the Redshift query optimizer when it detects conditions that could indicate performance issues, such as nested loops, missing statistics, or hash joins on large datasets. Querying this view surfaces actionable warnings that point directly to optimization opportunities. STL_USAGE_CONTROL logs changes to WLM configuration and records when queries are paused or canceled due to WLM rules, which is useful for WLM administration but not for identifying optimizer-generated performance alerts. STL_QUERY_METRICS provides a snapshot of current query queue activity and active query metrics, not historical alert events. STL_WLM_QUERY records query execution details like CPU time, rows processed, and disk spill within WLM service classes, which supports performance analysis but does not surface optimizer-generated alert events.

Explanation

AWS Database Migration Service is purpose-built for database migrations and supports keeping the source database fully operational during the migration process. It uses continuous data replication (change data capture) to minimize downtime and includes data validation capabilities to verify that the migrated data matches the source. AWS Snowball is a physical device for large-scale data transfers and does not support ongoing database replication or validation. AWS DataSync transfers files between storage systems and does not handle relational database migrations. AWS Glue is an ETL service for preparing and transforming data for analytics workloads, not for migrating transactional databases while keeping them live.