Re: Checking return value of SPI_execute

On 11/5/19 9:54 PM, Pavel Stehule wrote:
>
>
> st 6. 11. 2019 v 5:28 odesílatel Michael Paquier <michael(at)paquier(dot)xyz
> <mailto:michael(at)paquier(dot)xyz>> napsal:
>
> On Tue, Nov 05, 2019 at 05:21:25PM -0800, Mark Dilger wrote:
> > please find attached a patch fixing a problem previously
> discussed [1] about
> > the code inappropriately ignoring the return value from SPI_execute.
> >
> > I will be adding this to https://commitfest.postgresql.org/26/
> > shortly.
>
> Yes, this should be fixed.
>
> > -     SPI_execute(query, true, 0);
> > +     spi_result = SPI_execute(query, true, 0);
> > +     if (spi_result < 0)
> > +             elog(ERROR, "SPI_execute returned %s",
> SPI_result_code_string(spi_result));
>
> Any queries processed in xml.c are plain SELECT queries, so it seems
> to me that you need to check after SPI_OK_SELECT as only valid
> result.
>
>
> Is generic question if this exception should not be raised somewhere in
> spi.c - maybe at SPI_execute
>
> When you look to SPI_execute_plan, then checked errors has a character
> +/- assertions. All SQL errors are ended by a exception. This API is not
> too consistent after years what is used.
>
> I agree so this result code should be tested for better code quality.
> But this API is not consistent now, and should be refactored to use a
> exceptions instead result codes. Or instead error checking, a assertions
> should be used.
>
> What do you think about it?

I am creating another patch which removes most of the error codes from
the interface and uses elog(ERROR) or ereport(ERROR) instead, but I
anticipate a lot of debate about that design and wanted to get this
simpler patch into the queue. I don't think we need to reject this
patch in favor of redesigning the entire SPI API. Instead, we can apply
this patch as a simple bug fix, and then if it gets removed later when
the other, larger patch is committed, so be it.

Does that plan seem acceptable?

Mark Dilger