On Fri, Jun 17, 2016 at 9:32 AM, Andreas Joseph Krogh <andr...@visena.com> wrote:
> På torsdag 16. juni 2016 kl. 00:50:45, skrev Jeff Janes < > jeff.ja...@gmail.com>: > > On Wed, Jun 15, 2016 at 3:56 AM, Andreas Joseph Krogh <andr...@visena.com> > wrote: >> >> Hi. >> >> First; Is this the correct forum to ask questions about the Postgres >> Pro's new RUM-index? >> >> If not, please point me to the right forum. >> > > I think that https://github.com/postgrespro/rum/issues might be the best > forum. > > > Oleg and friends; Should we use GitHub-issues as forum (one issue per > question/thread?), pgsql-general or something else? > Andreas, we are hardly working on our internal version of rum and will open it after resolving some issues. I think the best place to discuss it is -hackers. > > > Note that GIN does almost what I want, except use the index when sorting >> by "sent"-timestamp. >> >> So I wonder if RUM can do any better? >> What I don't understand is how to have "folder_id" as part of the >> RUM-index so that I can search in *an array* of folders using the index, >> *AND* have the whole result sorted by "sent"-timestamp also using the >> RUM-index. >> > > I think you would have to implement an operator for integers for RUM much > like btree_gin does for GIN. Sorry don't know how to do that, except to > say look in the RUM code to see how it does it for time-stamps. > > >> >> In the (limited) documentation sorting using timestamp is done like this: >> >> ORDER BY sent <-> '2000-01-01'::TIMESTAMP >> >> which I don't understand; Why must one specify a value here, and how does >> that value affect the result? >> > > > This is essentially identical to ORDER BY ABS(sent - > '2000-01-01'::TIMESTAMP); except it can use the index. > > So maybe pick a constant outside the range of possible values, and use > that as one argument to <->. > > > This should be unnecessary and hidden from the user. Maybe some "ORDER BY > rum_timestamp(sent)" or something could abstract away stuff to make it much > clearer to the user? > -- > *Andreas Joseph Krogh* > CTO / Partner - Visena AS > Mobile: +47 909 56 963 > andr...@visena.com > www.visena.com > <https://www.visena.com> > >
