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Lessons Learned #558: What an Execution Plan XML Can Tell Us in Azure SQL Database

Jose_Manuel_Jurado's avatar
Jose_Manuel_Jurado
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Oct 11, 2026

During a performance investigation in Azure SQL Database, we requested the execution plan to understand what the query was doing. While reviewing the evidence, the customer asked a broader question: when you open the XML of an execution plan, what do you usually look for?

During a performance investigation in Azure SQL Database, we requested the execution plan to understand what the query was doing. While reviewing the evidence, the customer asked a broader question: ...
Updated Oct 11, 2026
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azure sql database
AZURE SQL DB
Execution Plans
Implicit Conversion
Lessons learned
parallelism
Query Optimization
query performance
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troubleshooting
subbuk's avatar
subbuk
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Oct 11, 2026

Nice work Jose as always! 

An execution plan XML can explain why a query behaved a certain way, but it should not be treated as an automatic tuning script. The right approach is to capture the actual plan from the slow execution, preserve the parameters and runtime evidence, then use that evidence to test a specific tuning change.

Takeaways for me
As a engineer -  we should use execution plan XML to build an evidence-backed hypothesis, not to jump straight to a fix.

And as customer - ensure to capture the actual slow execution with parameters and runtime metrics, then validate any tuning recommendation with measured before/after results.