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A company is migrating an on-premises PostgreSQL database to Amazon RDS for PostgreSQL. The database has a large table that is frequently accessed by reporting queries. The reporting queries filter on a column that has a high cardinality but low selectivity. To optimize query performance on this table, which design choice should the database specialist recommend?
Option D is correct because a covering index includes all columns needed by the reporting queries, allowing PostgreSQL to satisfy the query entirely from the index without accessing the heap (table) pages. This eliminates the overhead of random I/O for row lookups, which is espec…Read full explanation
A company is designing a new e-commerce platform using Amazon DynamoDB. The workload requires single-digit millisecond latency for user session data, which is accessed by session token. The session data is temporary and should be automatically deleted after 24 hours. Which DynamoDB design should the database specialist recommend?
DynamoDB Time to Live (TTL) automatically deletes expired items after a specified timestamp, making it ideal for session data that must be removed after 24 hours. This approach requires no additional infrastructure, meets the single-digit millisecond latency requirement by using …Read full explanation
A financial services company is migrating its Oracle database to Amazon Aurora PostgreSQL. The database runs a critical batch processing job every night that updates millions of rows. The company needs the migration to minimize downtime and ensure data integrity. Which AWS service should the database specialist use to perform the migration?
AWS DMS with ongoing replication (change data capture, CDC) is the correct choice because it enables a near-zero-downtime migration by continuously replicating changes from the source Oracle database to the target Aurora PostgreSQL while the source remains fully operational. Afte…Read full explanation
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