On Mon, Mar 21, 2016 at 5:41 PM, Andreas Joseph Krogh <andr...@visena.com> wrote:
> På lørdag 19. mars 2016 kl. 03:44:55, skrev Jeff Janes < > jeff.ja...@gmail.com>: > > On Wed, Mar 16, 2016 at 6:53 AM, Andreas Joseph Krogh <andr...@visena.com> > wrote: >> >> På onsdag 16. mars 2016 kl. 14:37:27, skrev Tom Lane <t...@sss.pgh.pa.us>: >> >> Andreas Joseph Krogh <andr...@visena.com> writes: >> > 1. Why isnt' folder_id part of the index-cond? >> >> Because a GIN index is useless for sorting. >> >> > 2. Is there a way to make it use the (same) index to sort by >> > received_timestamp? >> >> No. >> >> > 3. Using a GIN-index, is there a way to use the index at all for >> sorting? >> >> No. >> >> > 4. It doesn't seem like ts_rank uses the index for sorting either. >> >> Same reason. >> >> regards, tom lane >> >> >> So it's basically impossible to use FTS/GIN with sorting on large >> datasets? >> Are there any plans to improve this situation? >> > > I don't see why it would not be possible to create a new execution node > type that does an index scan to obtain order (or just to satisfy an > equality or range expression), and takes a bitmap (as produced by the > FTS/GIN) to apply as a filter. But, I don't know of anyone planning on > doing that. > > > Isn't this what Postgres Pro are planning? > http://postgrespro.com/roadmap/mssearch > > *"Unlike external special-purpose search engines, a full-text search > engine built in a DBMS is capable of combining full-text and attributive > search criteria in SQL query syntax. It is planned to improve the existing > PostgreSQL full-text search engine by extending the functionality of > Generalized Inverted Index (GIN) to make it capable of storing extra > information required for ranging query results. This search acceleration > will allow to go back from external full-text search engines, thus > facilitating system administration and use, reducing technology risks, and > improving information security."* > This is different feature ! Actually, we already have prototype of what Jeff suggested, we called it bitmap filtering, but failed to find use case where it provides benefits. Teodor will comment this idea more detail. > > -- > *Andreas Joseph Krogh* > CTO / Partner - Visena AS > Mobile: +47 909 56 963 > andr...@visena.com > www.visena.com > <https://www.visena.com> > >
