python: MYSQLdb. how to get columns name without executing select * in a big table?

You can use SHOW columns:

cursor.execute("SHOW columns FROM table_name")
print [column[0] for column in cursor.fetchall()]

FYI, this is essentially the same as using desc:

cursor.execute("desc table_name")
print [column[0] for column in cursor.fetchall()]

The correct way to do this would be to use "SHOW columns FROM table_name" however, you could also simply add a LIMIT to your existing query:

cursor.execute("SELECT * FROM table_name LIMIT 0")
print cursor.description

Try

cursor.execute("SELECT * FROM table_name LIMIT 1")

or

cursor.execute("SELECT * FROM table_name WHERE 1=0")

Both prevent massive amounts of data being rattled. The second one is perhaps more elegant. I've just checked, and even this works:

>>>cursor.execute("SELECT LEFT(long_text,5) as short_text FROM table_name WHERE 1=0")
>>>print cursor.description
(('short_text', 253, 0, 5, 5, 31, 0),)