EXEC(@SQL) vs. EXEC SP_EXECUTESQL: Which Dynamic SQL Approach Is Best for Performance?

SQL Server Dynamic SQL: Optimizing EXEC(@SQL) and EXEC SP_EXECUTESQL

When working with dynamic SQL in SQL Server, developers often choose between EXEC(@SQL) and EXEC SP_EXECUTESQL. Understanding the strengths and weaknesses of each is crucial for performance optimization.

EXEC(@SQL): The Simpler Approach

This method constructs a SQL string and executes it directly. Its simplicity is appealing, but it lacks explicit parameterization. This absence of parameter identification prevents the query optimizer from effectively reusing query plans.

EXEC SP_EXECUTESQL: Parameterized Efficiency

EXEC SP_EXECUTESQL offers a significant advantage through explicit parameter definition. This allows the query optimizer to prepare and cache query plans, leading to performance gains by eliminating repeated compilation overhead.

Key Differences:

• Query Plan Caching: SP_EXECUTESQL excels at plan reuse thanks to its parameterized nature. EXEC(@SQL) often results in recompilation for each execution, even with identical queries and varying parameters.
• Development Effort: EXEC(@SQL) is easier to implement initially, but SP_EXECUTESQL demands more careful parameter handling and adherence to its specific syntax.
• Database System Dependency: EXEC(@SQL) is more portable, relying on standard SQL. SP_EXECUTESQL is specific to SQL Server.

Best Practices and Further Reading

Erland Sommarskog's influential article, "The Curse and Blessings of Dynamic SQL," provides comprehensive guidance on the intricacies of dynamic SQL in SQL Server. This resource offers valuable insights into best practices and potential pitfalls, empowering developers to make informed choices between EXEC(@SQL) and EXEC SP_EXECUTESQL based on specific needs.

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