Re: [postgis-users] implement your own index
Mark, many thanks for all these very useful pointers. B. Zitat von Mark Cave-Ayland : Biddy wrote: María, thank you for the fast reply. However, these docs refer to the usage of GIST. If I understand it correctly, an R-tree is implemented on top of GIST. What if I don't want to use an R-tree? If I wanted to implement my own ...let's say I want to implement a quadtree or some other new, fancy index. How would I go about doing it? The GIST API currently does not support space partition-based nor ordered indices (see http://www.postgresql.org/docs/8.4/interactive/gist-implementation.html for the exact details). So if you wanted to implement a quadtree or nearest neighbour type index searches then you'd need to alter the GIST API or invent another index AM in PostgreSQL first. You may find the SP-GIST project interesting in this respect: http://www.cs.purdue.edu/spgist/. Additionally, is there a way to change the attributes with which the R-tree is built? Or at least see how the R-tree is built? It depends what attributes you are trying to modify. If they can be defined in terms of the GIST picksplit function then it is likely possible. In terms of visualising the R-Tree itself, Oleg and Teodor's gevel module from http://www.sai.msu.su/~megera/postgres/gist/ can be used as an aid to generate output suitable for rendering. HTH, Mark. -- Mark Cave-Ayland - Senior Technical Architect PostgreSQL - PostGIS Sirius Corporation plc - control through freedom http://www.siriusit.co.uk t: +44 870 608 0063 Sirius Labs: http://www.siriusit.co.uk/labs ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] implement your own index
Biddy wrote: María, thank you for the fast reply. However, these docs refer to the usage of GIST. If I understand it correctly, an R-tree is implemented on top of GIST. What if I don't want to use an R-tree? If I wanted to implement my own ...let's say I want to implement a quadtree or some other new, fancy index. How would I go about doing it? The GIST API currently does not support space partition-based nor ordered indices (see http://www.postgresql.org/docs/8.4/interactive/gist-implementation.html for the exact details). So if you wanted to implement a quadtree or nearest neighbour type index searches then you'd need to alter the GIST API or invent another index AM in PostgreSQL first. You may find the SP-GIST project interesting in this respect: http://www.cs.purdue.edu/spgist/. Additionally, is there a way to change the attributes with which the R-tree is built? Or at least see how the R-tree is built? It depends what attributes you are trying to modify. If they can be defined in terms of the GIST picksplit function then it is likely possible. In terms of visualising the R-Tree itself, Oleg and Teodor's gevel module from http://www.sai.msu.su/~megera/postgres/gist/ can be used as an aid to generate output suitable for rendering. HTH, Mark. -- Mark Cave-Ayland - Senior Technical Architect PostgreSQL - PostGIS Sirius Corporation plc - control through freedom http://www.siriusit.co.uk t: +44 870 608 0063 Sirius Labs: http://www.siriusit.co.uk/labs ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] implement your own index
María, thank you for the fast reply. However, these docs refer to the usage of GIST. If I understand it correctly, an R-tree is implemented on top of GIST. What if I don't want to use an R-tree? If I wanted to implement my own ...let's say I want to implement a quadtree or some other new, fancy index. How would I go about doing it? Additionally, is there a way to change the attributes with which the R-tree is built? Or at least see how the R-tree is built? Many thanks, B. Zitat von Maria Arias de Reyna : El Tuesday 18 May 2010, Biddy escribió: write your own spatial index. Do you mean this: http://postgis.refractions.net/docs/ch04.html#id2794434 ? Take a look at the docs, probably most of your questions are answered there. -- María Arias de Reyna Domínguez Área de Operaciones Emergya Consultoría Tfno: +34 954 51 75 77 / +34 607 43 74 27 Fax: +34 954 51 64 73 www.emergya.es ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
Re: [postgis-users] implement your own index
El Tuesday 18 May 2010, Biddy escribió: > write your own spatial index. Do you mean this: http://postgis.refractions.net/docs/ch04.html#id2794434 ? Take a look at the docs, probably most of your questions are answered there. -- María Arias de Reyna Domínguez Área de Operaciones Emergya Consultoría Tfno: +34 954 51 75 77 / +34 607 43 74 27 Fax: +34 954 51 64 73 www.emergya.es ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
[postgis-users] implement your own index
Hello everyone, I am new to PostGIS and I was wondering if anybody could give me some information on (or provide me with a pointer to information on) how to write your own spatial index. All help is greatly appreciated, many thanks, B. ___ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
