mysql extension treats "timestamp" column as "timestamp with timezone", causing data errors

[marhar]

Copying a mysql TIMEZONE column changes the value.

• DuckDB treats "timestamp" columns as "timestamp with timezone".
• This causes incorrect operation when comparing timestamp columns when not in UTC-0 timezone.
• my timezone: UTC-8

Expected results:

Copying a timestamp column in DuckDB does not change the timestamp value.

Actual Results:

Copying a timestamp column in DuckDB changes the timestamp value.

Execute in mysql:

-- $ mysql -u root -D testdb
create table a(t timestamp(6));
create table b(t timestamp(6));
insert into a values(now(6));
describe a;
-- +-------+--------------+------+-----+---------+-------+
-- | Field | Type         | Null | Key | Default | Extra |
-- +-------+--------------+------+-----+---------+-------+
-- | t     | timestamp(6) | YES  |     | NULL    |       |
-- +-------+--------------+------+-----+---------+-------+

Execute in duckdb:

-- set timezone='UTC'; -- note: my timezone is +8
ATTACH 'host=localhost user=root port=0 database=testdb' AS my(TYPE MYSQL);

select * from my.a;
insert into my.b select * from my.a;
select * from my.b;

describe my.a;

Execution Results:

select * from my.a;
┌───────────────────────────────┐
│               t               │
│   timestamp with time zone    │
├───────────────────────────────┤
│ 2024-12-16 09:40:40.396764-08 │
└───────────────────────────────┘
select * from my.b;
┌───────────────────────────────┐
│               t               │
│   timestamp with time zone    │
├───────────────────────────────┤
│ 2024-12-16 17:40:40.396764-08 │ <<<<<<<< value is offset, should be same as above
└───────────────────────────────┘

describe my.a;
┌─────────────┬──────────────────────────┬─────────┬─────────┬─────────┬─────────┐
│ column_name │       column_type        │  null   │   key   │ default │  extra  │
│   varchar   │         varchar          │ varchar │ varchar │ varchar │ varchar │
├─────────────┼──────────────────────────┼─────────┼─────────┼─────────┼─────────┤
│ t           │ TIMESTAMP WITH TIME ZONE │ YES     │  <<<<<< should be simple TIMESTAMP
└─────────────┴──────────────────────────┴─────────┴─────────┴─────────┴─────────┘

Note that the data error also shows up in MySQL:

mysql> select * from a;
+----------------------------+
| t                          |
+----------------------------+
| 2024-12-16 09:40:40.396764 |
+----------------------------+

mysql> select * from b;
+----------------------------+
| t                          |
+----------------------------+
| 2024-12-16 17:40:40.396764 | <<<< should be same as above
+----------------------------+

[Mytherin]

Thanks for reporting! I've pushed a fix in #111