An execution plan describes the operations the database engine expects to perform to execute a query. It can show scans, seeks, JOIN algorithms, sorting, filtering, and estimated costs.
When a JOIN query is slow, the execution plan can help identify expensive operations and possible optimization opportunities.
Review an execution plan to determine whether a large Orders table is being scanned instead of efficiently accessed through an index.
SELECT
c.CustomerName,
o.OrderAmount
FROM Customers c
INNER JOIN Orders o
ON c.CustomerID = o.CustomerID;Used by SQL developers, Data Engineers, DBAs, and performance analysts to optimize complex queries.
- Execution plans show how queries are processed.
- JOIN algorithms can be inspected.
- Table scans may be expensive on large datasets.
- Indexes may change the execution strategy.
- Execution plans are important for performance tuning.
What is an execution plan?
An execution plan describes the operations the database engine uses or plans to use to execute a SQL query.
Why inspect an execution plan?
It helps identify expensive operations and understand why a JOIN or query may be running slowly.