Enhance aggregate function `collect_set` and `collect_list` to support optional `max_size` param,
which enables to limit the number of elements in result array.
- change for Nereids
1. add a variable length parameter to the ctor of Count for a good error reporting of Count(a, b)
2. refactor StringRegexPredicate, let it inherit from ScalarFunction
3. remove useless class TypeCollection
4. use catalog.Type.Collection to check expression arguments type
5. change type coercion for TimestampArithmetic, divide, integral divide, comparison predicate, case when and in predicate. Let them same as legacy planner.
- change for legacy planner
1. change the common type of floating and Decimal from Decimal to Double
This pr mainly to optimize the histogram(👉🏻https://github.com/apache/doris/pull/14910) aggregation function. Including the following:
1. Support input parameters `sample_rate` and `max_bucket_num`
2. Add UT and regression test
3. Add documentation
4. Optimize function implementation logic
Parameter description:
- `sample_rate`:Optional. The proportion of sample data used to generate the histogram. The default is 0.2.
- `max_bucket_num`:Optional. Limit the number of histogram buckets. The default value is 128.
---
Example:
```
MySQL [test]> SELECT histogram(c_float) FROM histogram_test;
+-------------------------------------------------------------------------------------------------------------------------------------+
| histogram(`c_float`) |
+-------------------------------------------------------------------------------------------------------------------------------------+
| {"sample_rate":0.2,"max_bucket_num":128,"bucket_num":3,"buckets":[{"lower":"0.1","upper":"0.1","count":1,"pre_sum":0,"ndv":1},...]} |
+-------------------------------------------------------------------------------------------------------------------------------------+
MySQL [test]> SELECT histogram(c_string, 0.5, 2) FROM histogram_test;
+-------------------------------------------------------------------------------------------------------------------------------------+
| histogram(`c_string`) |
+-------------------------------------------------------------------------------------------------------------------------------------+
| {"sample_rate":0.5,"max_bucket_num":2,"bucket_num":2,"buckets":[{"lower":"str1","upper":"str7","count":4,"pre_sum":0,"ndv":3},...]} |
+-------------------------------------------------------------------------------------------------------------------------------------+
```
Query result description:
```
{
"sample_rate": 0.2,
"max_bucket_num": 128,
"bucket_num": 3,
"buckets": [
{
"lower": "0.1",
"upper": "0.2",
"count": 2,
"pre_sum": 0,
"ndv": 2
},
{
"lower": "0.8",
"upper": "0.9",
"count": 2,
"pre_sum": 2,
"ndv": 2
},
{
"lower": "1.0",
"upper": "1.0",
"count": 2,
"pre_sum": 4,
"ndv": 1
}
]
}
```
Field description:
- sample_rate:Rate of sampling
- max_bucket_num:Limit the maximum number of buckets
- bucket_num:The actual number of buckets
- buckets:All buckets
- lower:Upper bound of the bucket
- upper:Lower bound of the bucket
- count:The number of elements contained in the bucket
- pre_sum:The total number of elements in the front bucket
- ndv:The number of different values in the bucket
> Total number of histogram elements = number of elements in the last bucket(count) + total number of elements in the previous bucket(pre_sum).
MySQL [db]> SELECT SUM(a.r[1]) as active_user_num, SUM(a.r[2]) as active_user_num_1day, SUM(a.r[3]) as active_user_num_3day, SUM(a.r[4]) as active_user_num_7day FROM ( SELECT user_id, retention( day = '2022-11-01', day = '2022-11-02', day = '2022-11-04', day = '2022-11-07') as r FROM login_event WHERE (day >= '2022-11-01') AND (day <= '2022-11-21') GROUP BY user_id ) a;
ERROR 1105 (HY000): errCode = 2, detailMessage = sum requires a numeric parameter: sum(%element_extract%(a.r, 1))