Re: Yet another fast GiST build

On 07/10/2020 15:27, Andrey Borodin wrote:
> Here's draft patch with implementation of sortsupport for ints and floats.

> +static int
> +gbt_int4_cmp(Datum a, Datum b, SortSupport ssup)
> +{
> +    int32KEY   *ia = (int32KEY *) DatumGetPointer(a);
> +    int32KEY   *ib = (int32KEY *) DatumGetPointer(b);
> +
> +    if (ia->lower == ib->lower)
> +    {
> +        if (ia->upper == ib->upper)
> +            return 0;
> +
> +        return (ia->upper > ib->upper) ? 1 : -1;
> +    }
> +
> +    return (ia->lower > ib->lower) ? 1 : -1;
> +}

We're only dealing with leaf items during index build, so the 'upper' 
and 'lower' should always be equal here, right? Maybe add a comment and 
an assertion on that.

(It's pretty sad that the on-disk representation is identical for leaf 
and internal items, because that wastes a lot of disk space, but that's 
way out of scope for this patch.)

- Heikki