[postgis-users] Upgrading from PostgreSQL 8.0 with PostGIS 0. 9 to PostgreSQL 8.1 with PostGIS 1.0

[Paul Ramsey]

Actually, the data is *stored* in a C struct, what you see when you  
type "select geom from mytable" is the "canonical representation" of  
the geometry.  The canonical representation used to be "well known  
text" (WKT) which has the advantage of being human readable.  The  
trouble is, the canonical representation is used for things like  
database backup dump files, and really is spit out any time any  
client asks for the geometry.  That means the data is constantly  
going from the internal binary form to text to binary, and so on.   
This can cause very small drifts in the values, which means that it  
was possible to backup a database table, restore it, and find that  
the geometries were no longer exactly the same.  They were not *very*  
different, but they were a little different.

In general, using the OGC standard representation functions (astext,  
asbinary) is what people should do when pulling information out of  
the database.  Mapserver's PostGIS support (mappostgis.c) did this,  
and as a result when we changed the canonical form (and the on-disk  
form as well) for 1.0 mapserver remained compatible with the new  
versions of postgis, despite very very substantial changes to postgis.

Paul

On Jan 20, 2006, at 8:22 AM, Sears, Jeremy wrote:

> >>Unfortunately the geom column of my data again appear as a  
> strange string of characters where I expected to see something as  
> POINT, LINE etc.
>
> I asked the same question and was informed that this is normal. You  
> data should look like incoherent strings. Apparently this is how  
> the data are stored in newer versions of postgis.
>
> Glad to help
> Jeremy
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis- 
> users-bounces at postgis.refractions.net]On Behalf Of Mario Servin
> Sent: January 20, 2006 11:01 AM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] Upgrading from PostgreSQL 8.0 with  
> PostGIS 0. 9 to PostgreSQL 8.1 with PostGIS 1.0
>
> Thanks Jeremy. I used that and now postgis_restore works to the  
> end. Unfortunately the geom column of my data again appear as a  
> strange string of characters where I expected to see something as  
> POINT, LINE etc. I do not know what else can I do .....
>
>
> On 1/20/06, Sears, Jeremy <Jeremy.Sears at ccrs.nrcan.gc.ca> wrote:
> >>The postgis_restore.pl could create the dump list and also the  
> dump ascii but then gives an error because it does not allow me to  
> write down the password at the next >>step.
>
> I was having a simmilar problem. Each time I'd run  
> postgis_restore.pl It would promt for my password 3 time before  
> bailing, indicating that the password was incorrect. It was pointed  
> out to me that this can be avoided by setting the following  
> environment variables, PGUSER and PGPASSWORD. I also found it  
> useful to specify PGHOST, PGPORT, and PGDATA as well. You can set  
> the env variable at the cmmd prompt like this:
>
> >set PGUSER=username
>
> or you can set the in controlpanel-->system-->advanced-->
>
> hope that helps
> Jeremy
>
>
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net [mailto:postgis- 
> users-bounces at postgis.refractions.net ]On Behalf Of Mario Servin
> Sent: January 20, 2006 10:06 AM
> To: postgis-users at postgis.refractions.net
> Subject: [postgis-users] Upgrading from PostgreSQL 8.0 with PostGIS  
> 0.9 to PostgreSQL 8.1 with PostGIS 1.0
>
> Hi everybody,
> I failed completely to restore my data from a PostgreSQL 8.0 with  
> PostGIS 0.9 to PostgreSQL 8.1 with PostGIS 1.0. I have both  
> versions of PosgreSQL running in Windows. I follow instructions in  
> PostGIS docs from the PostgreSQL installation for upgrading. The  
> postgis_restore.pl could create the dump list and also the dump  
> ascii but then gives an error because it does not allow me to write  
> down the password at the next step. As I know something about Perl  
> I tried to modify the script without success.
> Additionally, I still have the results from the old shp2pgsql and  
> so I tried to insert the data form psql using \i  
> mysqlinsertionscript.sql. Tables are created ok, but geom columns  
> results in meaningless characters where it is supossed to be  
> something like "POINT (- 66.046532 -21.951437)" for example.
> Can anybody help me?.
> Regards,
>             Mario Servin
>
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