[postgis-users] JDBC-Postgis bug

[C F]

Hi David,
I've been messing around a little with your WKB4J application.  It's been 
working really great, except I had one issue with it.  I actually need to 
retrieve all associated record data along with the binary geometries.  Since 
the binary cursor returns all data as binary, I was having a heck of a time 
converting everything.  I was having some very strange and inconsistant 
results.... I was in endian hell.  Doing the following for retrieving 
geometries solved my problems and helped simplify/streamline the process..

bytea(asbinary(geom_col,'XDR'))

I modified that one aspect of your WKB4J app and the rest of the app is 
still running beautifully.  If this is an option for you, it *might* resolve 
the issues you're having..... I don't know... just thought I'd throw it out 
there.

>From: David Garnier <david.garnier at etudier-online.com>
>Reply-To: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
>To: PostGIS Users Discussion <postgis-users at postgis.refractions.net>
>Subject: [postgis-users] JDBC-Postgis bug
>Date: 18 Jun 2003 23:13:05 +0200
>
>Hello,
>
>I'm still working on my WKB4J project and I've been hitting this bug for
>some months. I perform a request to Postgis through JDBC, using a binary
>cursor :
>
>             Statement wkbSta = dbConn.createStatement();
>
>             wkbSta.execute("begin");
>             wkbSta.execute(
>                 "declare wkb_cursor binary cursor for " +
>completeSQLQuery);
>             ResultSet wkbRecords =
>                 wkbSta.executeQuery("fetch forward all in wkb_cursor");
>
>             byte[][] fields = new byte[words.length][];
>
>             while (wkbRecords.next()) {
>                 for (int i = 0; i < words.length; i++) {
>                     fields[i] = wkbRecords.getBytes(words[i]);
>                 }
>                 try {
>-->                  byte[] record = wkbRecords.getBytes("wkb");
>                 } catch (Exception e) {
>                     e.printStackTrace();
>                     log.error(e);
>                 }
>             }
>
>             wkbSta.execute("close wkb_cursor");
>             wkbSta.execute("end");
>             wkbRecords.close();
>             wkbSta.close();
>
>
>Here is the problem: when I execute this code with the same Connection
>object, the endian of the result changes after a while. I haven't
>quantified the effect exactly but it seems to happen on the third or
>fourth query. For example, for the same record, with a new Connection I
>would always get the correct result :
>[1, 6, 0, 0, 0, 1, 0, 0, 0, 1, 3, 0, 0, 0, 8, 0, 0, 0, 116, 3, 0, 0, 31,
>-53, 118, 82, -58, 92, 99, -64, 82, -18, -62, -81, 92, 51, 3, -64,
>
>While with a "used" Connecction, I would get:
>[0, 0, 0, 0, 6, 0, 0, 0, 1, 0, 0, 0, 0, 3, 0, 0, 0, 8, 0, 0, 3, 116,
>-64, 99, 92, -58, 82, 118, -53, 31, -64, 3, 51, 92, -81, -62, -18, 82,
>
>According to the OGC documentation, the first byte indicates the byte
>order (big endian or little endian) and the second array is really the
>little-endian version of the big-endian (this is actually a mix of
>bytes, ints and longs so it is not obvious). In my query, I always
>specify XDR (big endian).
>
>This problems is a hard one for me because it would really degrade the
>performance of the library if I had to reparse the whole array.
>
>So, any idea about this problem?
>
>Best Regards,
>
>--
>David Garnier <david.garnier at etudier-online.com>
>
>
>_______________________________________________
>postgis-users mailing list
>postgis-users at postgis.refractions.net
>http://postgis.refractions.net/mailman/listinfo/postgis-users

_________________________________________________________________
Add photos to your messages with MSN 8. Get 2 months FREE*.  
http://join.msn.com/?page=features/featuredemail