dutyu opened a new pull request, #27231:
URL: https://github.com/apache/doris/pull/27231
## Proposed changes
**Thanks for** pr #21855 to provide a wonderful reference.
Maybe it is very difficult and **cost-expensive** to implement **a
comprehensive logical plan adapter**, maybe there is just some small syntax
variations between doris and some other engines (such as hive/spark), so we can
just **focus on** the **difference** here.
This pr mainly focus on the **syntax difference between doris and hive**.
For instance, do some function tranformations and override some syntax
validations.
- add a dialect named `hive`
- move method `NereidsParser#parseSQLWithDialect` to `TrinoParser`
- extract some `FnCallTransformer`/`FnCallTransformers` classes, so we can
reuse the logic about the function transformers
- allow derived tables without alias when we set dialect to `hive`(legacy
and nereids parser are both supported)
- add some function transformers for hive built-in functions
### Test case (from our online doris cluster)
- Test derived table without alias
```sql
MySQL [(none)]> show variables like '%dialect%';
+---------------+-------+---------------+---------+
| Variable_name | Value | Default_Value | Changed |
+---------------+-------+---------------+---------+
| sql_dialect | hive | doris | 1 |
+---------------+-------+---------------+---------+
1 row in set (0.01 sec)
MySQL [(none)]> select * from (select 1);
+------+
| 1 |
+------+
| 1 |
+------+
1 row in set (0.03 sec)
MySQL [(none)]> set sql_dialect=doris;
Query OK, 0 rows affected (0.02 sec)
MySQL [(none)]> select * from (select 1);
ERROR 1248 (42000): errCode = 2, detailMessage = Every derived table must
have its own alias
MySQL [(none)]>
```
- Test hive functions
```sql
MySQL [(none)]> show global functions;
Empty set (0.01 sec)
MySQL [(none)]> show variables like '%dialect%';
+---------------+-------+---------------+---------+
| Variable_name | Value | Default_Value | Changed |
+---------------+-------+---------------+---------+
| sql_dialect | hive | doris | 1 |
+---------------+-------+---------------+---------+
1 row in set (0.01 sec)
MySQL [(none)]> select get_json_object('{"a":"b"}', '$.a');
+----------------------------------+
| json_extract('{"a":"b"}', '$.a') |
+----------------------------------+
| "b" |
+----------------------------------+
1 row in set (0.04 sec)
MySQL [(none)]> select split("a b c", " ");
+-------------------------------+
| split_by_string('a b c', ' ') |
+-------------------------------+
| ["a", "b", "c"] |
+-------------------------------+
1 row in set (1.17 sec)
```
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