# Proposed changes
- Refactor AggregateFunction
1. AggregateFunction implement ComputeSignature
3. Add a CustomSignature to dynamic compute signature, we can check input type and compute implicit cast type in the `customSignature` method
2. Add PartialAggType to record some type information before disassemble aggregate
4. Refine and create a custom catalog function when translate AggregateFunction, without `finalizeForNereids`
- Support explain plan
1. explain parsed plan select ...
5. explain analyzed plan select ...
6. explain rewritten/logical plan select ...
7. explain optimized/physical plan select ...
8. explain all plan select ...
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