Re: improve type conversion of SPI_processed in Python

On 1/9/18 15:54, Tom Lane wrote:
> Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> writes:
>> Here is a patch to improves how PL/Python deals with very large values
>> of SPI_processed. The previous code converts anything that does not fit
>> into a C long into a Python float. But Python long has unlimited
>> precision, so we should be using that instead. And in Python 3, int and
>> long as the same, so there is no need to deal with any variations anymore.
>
> I took a quick look at this. +1 for returning Python long all the time,
> but I wonder why the Python version dependency.

To keep returning an int in Python 2 in the cases it fits. Maybe that's
overkill.

> Our existing function
> PLyLong_FromInt64() believes that PyLong_FromLongLong is unconditionally
> available.

Interesting. I had coded this to account for the possibility that long
long does not exist on a 64-bit platform, but that situation probably
died with the first Alpha or something.

> I'd be inclined to code PLyObject_FromUint64() as an exact
> analog of PLyLong_FromInt64(), ie
>
> /* on 32 bit platforms "unsigned long" may be too small */
> if (sizeof(uint64) > sizeof(unsigned long))
> return PyLong_FromUnsignedLongLong(DatumGetUInt64(d));
> else
> return PyLong_FromUnsignedLong(DatumGetUInt64(d));
>
> and let Python worry about how to optimize the conversion.

Would that even be necessary? Why not use the LongLong variant all the
time then?

--
Peter Eisentraut http://www.2ndQuadrant.com/
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