Re: GIN improvements part 1: additional information

On Thu, Oct 3, 2013 at 10:48 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Thu, Oct 3, 2013 at 2:43 PM, Heikki Linnakangas
> <hlinnakangas(at)vmware(dot)com> wrote:
> > It seems we've all but decided that we'll require reindexing GIN indexes
> in
> > 9.4.
>
> I thought the consensus in Ottawa was strongly against that. I'm not
> aware that anyone has subsequently changed their position on the
> topic. Bruce is right to point out that we've done such things before
> and can therefore do it again, but just because we have the technical
> means to do it doesn't make it good policy.
>
> That having been said, if we do decide to break it...
>
> > Let's take the opportunity to change some other annoyances with the
> > current GIN on-disk format:
>
> ...then fixing as much as possible in one go-round is clearly a good plan.
>

Let's see what options we have at all. I see following:
1) Drop support old GIN on-disk format. But users will have to reindex
after pg_upgrade.
2) Insert kluges into GIN to support both old and new formats. So, kluges
are kluges :) I don't see elegant way to do it for now, because formats are
very different.
3) Upgrade GIN on-disk format in pg_upgrade. However, it would be rewriting
almost whole index. Is it much better than just reindex?
4) Fork GIN2, leave GIN as is. It would lead to much of duplicated code.
Any other options?

------
With best regards,
Alexander Korotkov.