Re: Small GIN optimizations (after 9.4)

On Sun, Feb  9, 2014 at 02:17:12PM +0400, Alexander Korotkov wrote:
> On Thu, Feb 6, 2014 at 8:31 PM, PostgreSQL - Hans-J rgen Sch nig <

> postgres@cybertec.at> wrote:
>
>     i think there is one more thing which would be really good in GIN and which
>     would solve a ton of issues.
>     atm GIN entries are sorted by item pointer.
>     if we could sort them by a "column" it would fix a couple of real work
>     issues such as ...
>
>             SELECT ... FROM foo WHERE "tsearch_query" ORDER BY price DESC LIMIT
>     10
>
>     ... or so.
>     it many cases you want to search for a, say, product and find the cheapest
>     / most expensive one.
>     if the tsearch_query yields a high number of rows (which it often does) the
>     subsequent sort will kill you.
>
>
> This is not intended to be a small change. However, some solution might be
> possible in post 9.4 gin improvements or in new secret indexing project which
> will be presented at PGCon :-)

Would any of the listed changes cause backward-incompatible changes to
the on-disk format, causing problems for pg_upgrade?