Answer
Join selection depends on:
- Row count estimates
- Sort order
- Indexes
- Estimated CPU and I/O cost
Quick Answer
SQL Server picks join algorithms based on input size and available indexes. Small outer table with indexed inner → Nested Loops. Both inputs sorted by join key → Merge Join (fast, no extra memory). Large unsorted inputs → Hash Match (memory-heavy, may spill). Missing indexes push everything toward Hash Match.
S
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