alamb commented on issue #888:
URL: 
https://github.com/apache/arrow-datafusion/issues/888#issuecomment-916816150


   Hi @sum12  -- 
   
   > it looks like the columns definitions are required. 
   
   I am not sure about this -- I think the following works (note there are no 
column definitions). I was imagining we would do something similar for CSV
   
   ```sql
   CREATE EXTERNAL TABLE something STORED AS PARQUET LOCATION 
'/Users/alamb/Downloads/demo.parquet';
   ```
   
   > Also if we are inferring the schema then the API currently needs to read a 
set of records to actually do the inference. Do we want to control the number 
of rows read (default is to read the entire file) ?
   
   I think having a setting (in 
https://docs.rs/datafusion/5.0.0/datafusion/execution/context/struct.ExecutionConfig.html)
 would be helpful. I think reading a thousand rows is probably a good default 
(as most CSV files will have easily detectable schemas in their initial rows if 
at all)


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