Aggregate Functions & Grouping
Conditional Aggregation with CASE & FILTER: Performance
**Performance:** - One query faster than multiple separate queries - All conditions processed in single pass - Simple conditions perform better - Index columns
**Performance:**
- One query faster than multiple separate queries
- All conditions processed in single pass
- Simple conditions perform better
- Index columns used in conditions
One query faster than multiple separate queries
All conditions evaluated in single pass
Index columns in conditions
Simple conditions perform better
Avoid deeply nested CASE expressions
Forgetting ELSE 0 causes NULL results
Creating overlapping conditions unintentionally
Using when WHERE would be simpler
Too many conditional aggregates hurts readability
Not handling NULL in conditions explicitly