Oracle Database provides several techniques to optimize data access from Object Storage, particularly in the context of Autonomous Database, leveraging external tables and advanced storage formats. The question asks for four correct methods, and based on Oracle documentation, the following are the most applicable:
Correct Answer (A):Scan avoidance using partitioned external tables
Partitioned external tables allow Oracle Database to skip irrelevant partitions when querying data stored in Object Storage. By organizing data into partitions (e.g., by date or region), the database engine can prune partitions that don’t match the query predicates, significantly reducing the amount of data scanned and improving performance. This is a well-documented optimization for external data access in Oracle Database and Autonomous Database environments.
Correct Answer (D):Scan avoidance using columnar pruning for columnar stores like parquet and orc
Columnar pruning is a technique where only the required columns are read from columnar file formats such as Parquet or ORC stored in Object Storage. These formats store data column-wise, enabling the database to avoid scanning entire rows or irrelevant columns, which is particularly efficient for analytical queries common in Autonomous Data Warehouse (ADW). This is a standard optimization supported by Oracle’s external table framework when accessing Object Storage.
Correct Answer (E):Optimized data archive using hybrid partitioned tables
Hybrid partitioned tables combine local database partitions with external partitions stored in Object Storage. This allows older, less frequently accessed data to be archived efficiently in the cloud while remaining queryable alongside active data in the database. The database optimizes access by seamlessly integrating these partitions, reducing costs and improving archival efficiency. This feature is explicitly supported in Oracle Database and enhanced in Autonomous Database for data lifecycle management.
Correct Answer (F):Optimized data archive using partitioned external tables
Similar to hybrid partitioned tables, using partitioned external tables alone optimizes data archiving by storing historical data in Object Storage with partitioning (e.g., by year). This method enables efficient querying of archived data by pruning unneeded partitions, offering a cost-effective and scalable archival solution. It’s a distinct approach from hybrid tables, focusing solely on external storage, and is widely used in Oracle environments.
Incorrect Options:
B. Scan avoidance using columnar pruning for .csv files
CSV files are row-based, not columnar, and lack the internal structure of formats like Parquet or ORC. While Oracle can read CSVs from Object Storage via external tables, columnar pruning is not applicable because CSVs don’t support column-wise storage or metadata for pruning. This makes this option incorrect as a specific optimization technique, though basic predicate pushdown might still reduce scanning to some extent.
C. Scan avoidance using block skipping when reading parquet and orc files
Block skipping (or row group skipping) is a feature in some database systems where metadata in Parquet or ORC files allows skipping entire blocks of data based on query filters. While Oracle supports Parquet and ORC through external tables and can leverage their columnar nature (via pruning), “block skipping” is not explicitly highlighted as a primary optimization in Oracle’s documentation for Autonomous Database. It’s more commonly associated with systems like Apache Spark or Hive. Oracle’s focus is on columnar pruning and partitioning, making this option less accurate in this context.
Why Four Answers?
The question specifies “four ways,” and while six options are provided, A, D, E, and F are the most directly supported and documented methods in Oracle Autonomous Database for optimizing Object Storage access. Options B and C, while conceptually related to data access optimizations, are either inapplicable (CSV lacks columnar structure) or not explicitly emphasized (block skipping) in Oracle’s feature set for this purpose.
This selection aligns with Oracle’s focus on partitioning and columnar formats for efficient cloud data access, ensuring both performance and archival optimization.
[Reference:, External Tables and Object Storage, Hybrid Partitioned Tables, Autonomous Database Data Loading, ]
