Re: [postgis-users] PostGIS Geometry column
От | Oleg |
---|---|
Тема | Re: [postgis-users] PostGIS Geometry column |
Дата | |
Msg-id | 43F99975.9080705@iwk.uka.de обсуждение исходный текст |
Список | pgsql-novice |
Hi Nikolas, Hi Michael, Thanks a lot for your help. I think asText function could do the job we need. Best regards Oleg Nicolas Ribot schrieb: >>Dear All, >>While workin with PostgreSQL 7.4.6 Geometry was stored as String for >>example: >>SRID=-1;POINT(135.744865606022 304.591390378093) >>Now we have installed PostgreSQL 8.1.3. and included in the installer >>PostGIS. >>Geometries are stored in a different format for example: >>01010000003E580C9953964A41F76AF257F9CD5441 >>Is there a way to set up PostgreSQL8.1 or PostGIS to store geometries in >>String format as it was prviously? >>Thanks a lot in advance >>Oleg >> >> >> > >Hi Oleg. >I don't think it is possible. Postgis changed the way it stores >geometries internally, for space and performanace reason, if I >remenber well. >This format also avoids coordinate precision reduction as it could >happen with a textual format. >You can still display geometries as text by calling textual >representation functions when selecting geometries: >asText() (so srid displayed, OGS-compliant function) >asEXKT (srid dislpayed before the geometry). > >Nicolas >_______________________________________________ >postgis-users mailing list >postgis-users@postgis.refractions.net >http://postgis.refractions.net/mailman/listinfo/postgis-users > > To make some light on the question: PostGIS *NEVER* stored geometries in Text format. Internal representation has always been in binary form. The difference between 0.x and 1.x is the *canonical text output representation* The canonical text output representation is what you get when fetching a Geometry object from a text cursor. This is what you get with the 'psql' monitor application, for example. Most importantly, canonical text output representation is the representation used when *dumping* a database. This is the exact reason why it changed betseen 0.x and 1.x: to allow lossless dump/restore operations. I hope this clarify things. --strk; Michael Fuhr schrieb: PostGIS is a separate project from PostgreSQL so you'd be better off asking questions about it on the postgis-users mailing list. http://postgis.refractions.net/mailman/listinfo/postgis-users The change you're seeing is due to a different version of PostGIS, not a different version of PostgreSQL. Recent versions of PostGIS (since 1.0, I think) display a different "canonical form" than older versions did; search the postgis-users and postgis-devel archives for discussion and rationale. You can use the AsText or AsEWKT functions to get the Well-Known Text representation: postgis=> SELECT geom, AsText(geom) FROM foo; geom | astext --------------------------------------------+------------------------ 010100000077BE9F1A2FDD5E40AC1C5A643BDD8E40 | POINT(123.456 987.654) (1 row)
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