lgbo-ustc opened a new issue, #7895:
URL: https://github.com/apache/incubator-gluten/issues/7895
### Description
To compute the average of integers, vanilla need to convert the integers
into doubles first.
Compare the following two ways in `CH`
```sql
1 row in set. Elapsed: 0.015 sec. Processed 10.00 million rows, 80.00 MB
(655.54 million rows/s., 5.24 GB/s.)
Peak memory usage: 113.21 KiB.
f2386dc7dd0d :) select avg(cast(number as Double)) from numbers(10000000);
SELECT avg(CAST(number, 'Double'))
FROM numbers(10000000)
Query id: 531d1858-0afa-4bcd-9e03-4615f129b978
┌─avg(CAST(number, 'Double'))─┐
1. │ 4999999.5 │ -- 5.00 million
└─────────────────────────────┘
```
```sql
f2386dc7dd0d :) select avg(cast(number as Double)) from numbers(10000000);
SELECT avg(CAST(number, 'Double'))
FROM numbers(10000000)
Query id: 235d8e41-19e5-4b94-92b5-b400fe10fdee
┌─avg(CAST(number, 'Double'))─┐
1. │ 4999999.5 │ -- 5.00 million
└─────────────────────────────┘
1 row in set. Elapsed: 0.039 sec. Processed 10.00 million rows, 80.00 MB
(258.45 million rows/s., 2.07 GB/s.)
Peak memory usage: 114.16 KiB.
```
Removing the cast operation will bring significant improvement.
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