[postgis-users] WKB format

[Paul Ramsey]

Poke around some more. My guess is that this problem adheres to the JDBC
driver in some manner. We can retrieve WKB directly from binary cursors
with no problem via libpq. It could be that pgsql is squashing the
results of the WKB query into 7 bits because it is not a known 8bit
type, and the cursor is not 8bit. Can you do clean getBytes against
bytea types using text cursors?
Perhaps Dave/Chris could answer: why are we using a special type (wkb)
for the wkb results instead of just a bytea?

P.

David Garnier wrote:
> 
> OK, I think I get it from reading the source. PostGIS actually parses the binary data into an hexadecimal string and returns it. If I try to read my data with a getString, it looks fine, just like in plsql.
> 
> Now, there is a way to get the real bytes? A byte array that would match the specification of the WKB format? Or are we stuck with Strings till the end of times?
> 
> Best Regards,
> David Garnier
> 
> On Thu, 4 Jul 2002 21:24:18 +0200
> David Garnier <david.garnier at etudier-online.com> wrote:
> 
> > Hello,
> >
> > I'm working on this WKBReader in java, and I have some problems getting the data out of postgres. I use the following query:
> > select asbinary(the_geom,'NDR') as wkb , astext(the_geom) as wkt  from road_shapes limit 25
> > Then I do a getBytes on wkb:
> > From java I got this: 303130353030303030303031303030303030303130323030303030303033303030303030373532324331353433334641353943303130354130463546323630303434343034324231313533343244464235394330334132313734443032353030343434303734354643453643353746433539433032334639344132303235303034343430
> >
> > From plsql, I got this:
> > 0105000000010000000102000000030000007522C15433FA59C0105A0F5F2600444042B115342DFB59C03A2174D025004440745FCE6C57FC59C023F94A2025004440
> >
> > I think that there is two problems: the fourth bit of the each byte is set null. That would explain why there is no values above 7.
> >
> > I'm thinking that this might be related to different encoding schemes between Java and postgres.
> >
> > I figured that I would just ask around before diving head first into the source code of postgis.
> >
> > Best Regards,
> > David Garnier
> >
> > _______________________________________________
> > postgis-users mailing list
> > postgis-users at postgis.refractions.net
> > http://postgis.refractions.net/mailman/listinfo/postgis-users
> >
> 
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users

-- 
      __
     /
     | Paul Ramsey
     | Refractions Research
     | Email: pramsey at refractions.net
     | Phone: (250) 885-0632
     \_