Re: questions about how to implement a gist index

On Tue, Jun 28, 2016 at 12:44 AM, Riccardo Vianello
<riccardo(dot)vianello(at)gmail(dot)com> wrote:
> Hi all,
>
> I'm trying to contribute some improvements to the implementation of a gist
> index that is part of an open source project and it would be really nice if
> anyone could help me answer some questions.
>
> I would like to use different data structures to represent the internal and
> leaf entries. I think I have found several examples in the postgresql source
> code where a variable length array is used to pack different data
> consistently with the value of a "type" attribute. Is this the suggested way
> to proceed, or would it be also possible to use two actually different data
> structures? I at first considered this latter approach, but some erroneous
> behavior suggested that maybe I am not fully clear about which data
> structure should be produced or expected by some parts of the
> implementation.
>
> Could you please also help me understand the difference (if any) between
> using the GIST_LEAF macro or the leafkey attribute of the GISTENTRY data
> structure?

Yes, this is confused.

GIST_LEAF is TRUE if key is in leaf page.

bool leafkey points if TRUE that key contains value from heap.

>
> Thank you very much in advance,
>
> Riccardo
>
>