betodealmeida commented on PR #30903:
URL: https://github.com/apache/superset/pull/30903#issuecomment-2532291633
> What will happen if I accidently make a change to a query which will
result in zero rows returned - all columns including metadata will be
permanently removed?
It should be fine, since the cursor should still return a description of the
columns even if the number of rows is 0. For example, for Postgres:
```python
import psycopg2
query = "SELECT * FROM your_table WHERE 1=0;" # Query guaranteed to return
zero rows
db_config = {
"dbname": "DB",
"user": "user",
"password": "password",
"host": "host",
"port": 5432,
}
with psycopg2.connect(**db_config) as conn:
with conn.cursor() as cursor:
cursor.execute(query)
print("Cursor description:")
for col in cursor.description:
print(
f"Name: {col.name}, Type: {col.type_code}, Display Size:
{col.display_size}"
)
```
For a test table this prints:
```
Cursor description:
Name: show_id, Type: 25, Display Size: None
Name: type, Type: 25, Display Size: None
Name: title, Type: 25, Display Size: None
Name: director, Type: 25, Display Size: None
Name: country, Type: 25, Display Size: None
Name: date_added, Type: 25, Display Size: None
Name: release_year, Type: 23, Display Size: None
Name: rating, Type: 25, Display Size: None
Name: duration, Type: 25, Display Size: None
Name: listed_in, Type: 25, Display Size: None
Name: description, Type: 25, Display Size: None
Name: iso_date_added, Type: 25, Display Size: None
Name: iso_release_year, Type: 25, Display Size: None
Name: xata_version, Type: 23, Display Size: None
Name: xata_createdat, Type: 1184, Display Size: None
Name: xata_updatedat, Type: 1184, Display Size: None
Name: xata_id, Type: 25, Display Size: None
```
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