Re: Add reject_limit option to file_fdw

On 2024/11/05 22:30, torikoshia wrote:
>> Thanks for the patch! Could you add it to the next CommitFest?
>
> Added an entry for this patch:
> https://commitfest.postgresql.org/50/5331/

Thanks!

>> +ALTER FOREIGN TABLE agg_bad OPTIONS (reject_limit '1');
>> +SELECT * FROM agg_bad;
>> +  a  |   b
>> +-----+--------
>> + 100 | 99.097
>> +  42 | 324.78
>> +(2 rows)
>>
>> Wouldn't it be better to include a test where a SELECT query fails, even with
>> on_error set to "ignore," because the number of errors exceeds reject_limit?
>
> Agreed.

As for the agg.bad2 file that your latest patch added:

Instead of adding a new bad input file, what do you think about simply appending
"1;@bbb@" to the existing agg.bad file and adjusting sql/file_fdw.sql as follows?
This approach might keep things simpler.

-------------------
-\set filename :abs_srcdir '/data/agg.bad2'
-ALTER FOREIGN TABLE agg_bad OPTIONS (SET filename :'filename', ADD reject_limit '1');
+ALTER FOREIGN TABLE agg_bad OPTIONS (ADD reject_limit '1');
SELECT * FROM agg_bad;
ALTER FOREIGN TABLE agg_bad OPTIONS (SET reject_limit '2');
-------------------

>> +  <varlistentry>
>> +   <term><literal>reject_limit</literal></term>
>>
>> This entry should be placed right after the on_error option,
>> following the same order as in the COPY command documentation.
>>
>>
>>> Based on the synopsis of the CREATE/ALTER FOREIGN TABLE commands, the value for the foreign table's option must be single-quoted. I’m not entirely sure if this is the correct approach, but in order to accommodate this, the patch modifies the value of reject_limit option to accept not only numeric values but also strings.
>>>
>>
>> I don't have a better approach for this, so I'm okay with your solution.
>> Just one note: it would be helpful to explain and comment
>> why defGetCopyRejectLimitOption() accepts and parses both int64 and
>> string values.
>
> Added a comment for this.

Thanks for adding the comment. It clearly states that REJECT_LIMIT can be
a single-quoted string. However, it might also be helpful to mention that
it can be provided as an int64 in the COPY command option. How about
updating it like this?

------------------------------------
REJECT_LIMIT can be specified in two ways: as an int64 for the COPY command
option or as a single-quoted string for the foreign table option using
file_fdw. Therefore this function needs to handle both formats.
------------------------------------

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION