Re: Question about RUM-index
| От | Jeff Janes |
|---|---|
| Тема | Re: Question about RUM-index |
| Дата | |
| Msg-id | CAMkU=1yOO8ARgTJd50oCiXGn7oMS2xd0=vHB8g_H8aLTLKf7=Q@mail.gmail.com обсуждение исходный текст |
| Ответ на | Question about RUM-index (Andreas Joseph Krogh <andreas@visena.com>) |
| Ответы |
Re: Question about RUM-index
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| Список | pgsql-general |
On Wed, Jun 15, 2016 at 3:56 AM, Andreas Joseph Krogh <andreas@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'::TIMESTAMPwhich 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
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