Final answer:
To improve external table performance, one can partition the table, choose efficient file formats like Parquet or ORC, use compression techniques to reduce data size, optimize the reading process with predicate pushdown or indexing, and ensure the storage system is well-optimized for speed.
Step-by-step explanation:
To improve the performance of an external table in a database system, there are several strategies one can employ. One way is to partition the external table. Partitioning helps in managing and accessing subsets of data more efficiently, thus reducing the query execution time. Another way is to choose the proper file format. For instance, columnar formats like Parquet or ORC often provide better compression and performance over row-based formats like CSV. Additionally, use compression techniques to minimize the data footprint and improve read times. It's also important to optimize the reading process by using techniques such as predicate pushdown, where filtering is done as early as possible in the data retrieval process, or by indexing, which can significantly speed up the access to the required data. Lastly, ensure the underlying storage system is optimized for read/write operations and network throughput is sufficient for data transfer.