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. > > 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 <->. Cheers, Jeff
