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SummingMergeTree vs AggregatingMergeTree
TL;DR
SummingMergeTree is simple and fast for sum operations. AggregatingMergeTree handles complex aggregations (averages, unique counts) but requires AggregateFunction types and State/Merge functions. Start with SummingMergeTree unless you need complex aggregations.
Key Differences
| Feature | SummingMergeTree | AggregatingMergeTree |
|---|---|---|
| Operations | Sum only | Sum, avg, uniq, quantile, etc. |
| Functions | Regular SQL functions | State/Merge functions required |
| Complexity | Simple, out-of-the-box | Requires AggregateFunction types |
| Use case | Simple counters, metrics | Complex analytics, dashboards |
Use SummingMergeTree for simple sums. Use AggregatingMergeTree when you need averages, unique counts, or other complex aggregations that SummingMergeTree can't handle.