If specified, got a column of constant. otherwise an incremental series like it always be.
mysql> select * from numbers("number" = "5", "const_value" = "-123");
+--------+
| number |
+--------+
| -123 |
| -123 |
| -123 |
| -123 |
| -123 |
+--------+
5 rows in set (0.11 sec)
This pr makes three changes to the display of complex types：
1. NULL value in complex types refers to being displayed as `null`, not `NULL`
2. struct type is displayed as "column_name": column_value
3. Time types such as `datetime` and `date`, are displayed with double quotes in complex types. like
`{1, "2023-10-26 12:12:12"}`
This pr also do a code refactor:
1. nesting_level is set to a member variable of the `DataTypeSerDe`, rather than a parameter in methods.
What's more, this pr fix a bug that fileSize is not correct, introduced by this pr: #25854
### Before:
return errors when tvf queries an empty file or an error uri:
1. get parsed schema failed, empty csv file
2. Can not get first file, please check uri.
### Now:
we just return empty set when tvf queries an empty file or an error uri.
```sql
mysql> select * from s3(
"uri" = "https://error_uri/exp_1.csv",
"s3.access_key"= "xx",
"s3.secret_key" = "yy",
"format" = "csv") limit 10;
Empty set (1.29 sec)
```
sort out the test cases of external table.
After modify, there are 2 directories:
1. `external_table_p0`: all p0 cases of external tables: hive, es, jdbc and tvf
2. `external_table_p2`: all p2 cases of external tables: hive, es, mysql, pg, iceberg and tvf
So that we can run it with one line command like:
```
sh run-regression-test.sh --run -d external_table_p0,external_table_p2
```
