[postgis-devel] Re: Rounding off coordinates (from Postgis-users)

[Paul Ramsey]

Gino,
Good help to be had on postgis-devel.
The only "internal" debugging scheme in pgsql is classic "print your 
state until you die" debugging, which you can do using the pgsql 
logging facility (there should be lots of commented out examples in the 
postgis code). For more advanced debugging, you should use the standard 
GNU debugger, gdb.  The trick there is to not attach gdb to the main 
postmaster, but to the postgres backend you are actually running the 
command within.
P

On Tuesday, June 29, 2004, at 06:14 AM, Gino Lucrezi wrote:

>> Write up the function... base it on the parameters of the standard 
>> pgsql
>> round function that Charlton has demonstrated below, it would be a
>> useful addition.
>
> I started writing both a ROUND and a TRUNC function.
>
> I got yesterday's CVS build, and started browsing the code to see 
> where I could add it.
>
> My model is the translate function, which works in a similar way; it 
> has a geometry argument and some numeric arguments, it scans all 
> points in the geometry and performs some manipulation on them based on 
> the numeric arguments.
>
> It compiles perfectly, but it crashes PostgreSQL with no explaination.
>
> I need of some debugging tips... is there any debug facility in 
> PostgreSQL/Postgis?
>
> By the way, I was also thinking about Markus and strk's comments. It's 
> not just a matter of rounding off point coordinates, you'd have to 
> remove duplicates and I fear it might still cause some incorrect 
> geometries. It would still be OK for human reading.
> Any suggestions would be welcome, too.
>
> Gino Lucrezi
> Penta Consulting Services Srl
>
>
>
      Paul Ramsey
      Refractions Research
      Email: pramsey at refractions.net
      Phone: (250) 885-0632