Question 1

How do I install the MAT Calcite plugin in Eclipse MAT?

Accepted Answer

Ensure you have MAT 0.14.0+ and Java 17. Open Help > Install New Software, add the update site URL (stable or early access), select the 'SQL for Memory Analyzer' category, and follow the prompts. Restart MAT after installation.

Question 2

Can I use SQL joins to find memory leaks in heap dumps?

Accepted Answer

Yes, the plugin supports SQL joins to analyze object relationships. For example, you can join java.lang.String and java.net.URL tables to identify retained objects or duplicate patterns, as shown in the sample queries.

Question 3

What's the difference between MAT Calcite plugin and MAT's built-in OQL?

Accepted Answer

MAT Calcite plugin uses standard SQL with full join, group by, and order by support, while MAT's OQL is more limited. Use Calcite for complex relational queries and OQL for simpler object-based queries.

Question 4

How to optimize SQL queries for large heap dumps?

Accepted Answer

Use the 'explain plan for' feature to view execution plans and identify bottlenecks. Focus on filtering early and avoiding unnecessary columns, as the roadmap mentions projection support is planned but not yet implemented.

Question 5

Does it support querying heap dumps from the command line?

Accepted Answer

Yes, use './MemoryAnalyzer -application MatCalcitePlugin.execute ' for batch processing. This is useful for automated analysis without the GUI.

Question 6

Is there a way to map custom Java classes to SQL tables automatically?

Accepted Answer

The plugin automatically maps all Java classes in the heap dump to tables under the 'heap' schema. Use double-quoted identifiers like '"com.example.MyClass"' to reference them, with fields becoming columns.

MAT Calcite plugin

What is MAT Calcite plugin?

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