Answer
The optimizer evaluates many query strategies using statistics and metadata.
It selects the lowest estimated cost plan.
Quick Answer
The query optimizer is SQL Server's brain for plan selection. It generates multiple candidate plans, estimates the cost of each using statistics and cardinality, and picks the one with the lowest estimated cost. It's cost-based, not rule-based — which is why bad statistics lead directly to bad plans.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ