Which DB2 tool can be used to identify inefficient SQL statements without actually executing those statements?

Introduction / Context:
This question examines DB2 performance tuning tools. When optimizing SQL, it is often useful to analyze access plans and estimated costs without running the statements on large data sets. DB2 provides tools that show how queries will be executed, highlighting potential inefficiencies such as full table scans or poorly chosen indexes.

Given Data / Assumptions:

The environment uses DB2 databases.

The goal is to find inefficient SQL based on access plans rather than runtime behavior.

Graphical tools are available to display explain information.

The database has statistics collected so that the optimizer can estimate costs.

Concept / Approach:
Visual Explain is a DB2 tool that displays the access plan chosen by the optimizer for a given SQL statement. It can show join strategies, index usage, and estimated resource consumption. Because it relies on the EXPLAIN facility rather than full execution, Visual Explain can be used to identify inefficiencies before statements are run in production.

Step-by-Step Solution:
1. Recall that EXPLAIN and related tools provide access plan information without executing queries. 2. Visual Explain is specifically designed to graphically represent EXPLAIN output. 3. QMF is a query and reporting tool, not focused solely on explain plans. 4. Task Center is used for scheduling and managing tasks, not for detailed access plan analysis. 5. Development Center assists in application development but does not specialize in visualizing SQL access plans.

Verification / Alternative check:
DB2 documentation shows that Visual Explain works with EXPLAIN data and allows users to view plans, estimated CPU cost, I O cost, and cardinalities. It is widely recommended in tuning guides.

Why Other Options Are Wrong:
QMF can run SQL and report results, but it does not primarily analyze explain plans visually.
Task Center deals with job management and automation rather than SQL tuning.
Development Center helps create procedures and objects but is not the main performance analysis interface.

Common Pitfalls:
Users sometimes attempt to tune queries solely by running them and observing elapsed time, which can be misleading on small test data. Using Visual Explain encourages a more systematic approach based on optimizer decisions, index design, and join methods.

Final Answer:
The correct tool is Visual Explain.