CREATE EXTERNAL TABLE from CSV creates a table with no columns if there is just a header row

[andygrove]

Describe the bug

CREATE EXTERNAL TABLE from CSV creates a table with no columns if there is just a header row.

To Reproduce

Create test file:

echo "station_id,date,val,type" > weather.csv

In datafusion-cli:

CREATE EXTERNAL TABLE weather STORED AS CSV WITH HEADER ROW LOCATION 'weather.csv';

Table is created:

❯ show tables;
+---------------+--------------------+------------+------------+
| table_catalog | table_schema       | table_name | table_type |
+---------------+--------------------+------------+------------+
| datafusion    | public             | weather    | BASE TABLE |
| datafusion    | information_schema | tables     | VIEW       |
| datafusion    | information_schema | views      | VIEW       |
| datafusion    | information_schema | columns    | VIEW       |
+---------------+--------------------+------------+------------+

But it has no columns:

❯ select * from information_schema.columns;
+---------------+--------------+------------+-------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+-------------------------+---------------+--------------------+---------------+
| table_catalog | table_schema | table_name | column_name | ordinal_position | column_default | is_nullable | data_type | character_maximum_length | character_octet_length | numeric_precision | numeric_precision_radix | numeric_scale | datetime_precision | interval_type |
+---------------+--------------+------------+-------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+-------------------------+---------------+--------------------+---------------+
+---------------+--------------+------------+-------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+-------------------------+---------------+--------------------+---------------+

Works fine if there is data:

❯ select * from information_schema.columns;
+---------------+--------------+------------+-------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+-------------------------+---------------+--------------------+---------------+
| table_catalog | table_schema | table_name | column_name | ordinal_position | column_default | is_nullable | data_type | character_maximum_length | character_octet_length | numeric_precision | numeric_precision_radix | numeric_scale | datetime_precision | interval_type |
+---------------+--------------+------------+-------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+-------------------------+---------------+--------------------+---------------+
| datafusion    | public       | weather    | station_id  | 0                |                | NO          | Int64     |                          |                        |                   |                         |               |                    |               |
| datafusion    | public       | weather    | date        | 1                |                | NO          | Date32    |                          |                        |                   |                         |               |                    |               |
| datafusion    | public       | weather    | val         | 2                |                | NO          | Int64     |                          |                        |                   |                         |               |                    |               |
| datafusion    | public       | weather    | type        | 3                |                | NO          | Utf8      |                          | 2147483647             |                   |                         |               |                    |               |
+---------------+--------------+------------+-------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+-------------------------+---------------+--------------------+---------------+

Expected behavior
See above

Additional context
None

[comphead]

@andygrove I'll take it

[sadilet]

@comphead Hey, sorry, I didn't see your comment yesterday. I've started investigating this as soon as this issue got out, next time will notify about that and avoid such cases.

[comphead]

@sadilet :) looks like we submitted PRs the same time.
@andygrove you can take any you like.

[sadilet]

@comphead Your code has tests. It makes sense to close my PR.