Answer: WHERE

Partition elimination is a performance optimization technique in Azure Synapse Analytics dedicated SQL pool that allows the query engine to skip scanning partitions that don't contain relevant data for a query. To maximize partition elimination benefits, you should include a **WHERE clause** in your Transact-SQL queries that filters on the partitioning column. **Why WHERE clause is optimal:** - The WHERE clause allows you to specify filter conditions that align with the table's partitioning scheme - When the WHERE clause predicates match the partitioning column, the query optimizer can identify and eliminate irrelevant partitions from the execution plan - This reduces I/O operations and improves query performance by only scanning partitions that contain the requested data - For example, if a table is partitioned by month, a WHERE clause filtering on a specific month allows the engine to scan only that month's partition **Why other options are less suitable:** - **JOIN**: While JOIN operations can sometimes leverage partition elimination when joining on partitioning columns, this is not the primary or most reliable method for maximizing partition elimination - **DISTINCT**: This clause removes duplicate rows but doesn't inherently enable partition elimination based on partitioning columns - **GROUP BY**: This clause aggregates data but doesn't directly facilitate partition elimination unless combined with appropriate WHERE clause filtering The key principle is that partition elimination works best when query predicates in the WHERE clause directly reference the partitioning column, allowing the optimizer to prune unnecessary partitions before query execution.

Author: LeetQuiz Editorial Team