There is no data in the result of full table aggregation calculation for an empty table

**Bug Description**
There is no data in the result of full table aggregation calculation for an empty table

+ case
```yaml
- id: 3
desc: "表是空的"
tags: ["TODO","@chengjing,bug,"]
mode: request-unsupport
inputs:
-
columns : ["id bigint","c1 string","c2 int","c7 timestamp"]
indexs: ["index1:c1:c7"]
sql: select count(c2) as v1,max(c2) as v2,min(c2) as v3,avg(c2) as v4,sum(c2) as v5 from {0};
expect:
order: c1
columns: ["v1 int","v2 int","v3 int","v4 double","v5 int"]
rows:
- [0,null,null,null,null]
```

**Expected Behavior**
Expect to have data
**Relation Case**
test_udaf_table.yaml id:3
**Steps to Reproduce**

1.
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The bug is in test_udaf_table.yaml case id:3, which expects aggregation results (count, max, min, avg, sum) on an empty table to return a row with nulls. Look at the SQL aggregation logic for empty tables, likely in the query engine or UDAF implementation. Run the specific test to see the current failure, then trace where empty table results are generated.

Written by the indexing model from the issue text.