On 02/04/09 16:58, Markus Neteler wrote:
On Thu, Apr 2, 2009 at 4:51 PM, Moritz Lennert
<[email protected]> wrote:
On 02/04/09 16:00, Markus Neteler wrote:
On Thu, Apr 2, 2009 at 1:43 PM, Markus Neteler <[email protected]> wrote:
On Wed, Apr 1, 2009 at 6:05 PM, Paolo Cavallini <[email protected]>
v.dissolve input=reg...@nuovo layer=1 column=REGIAO output=reg_diss
dbmi: Protocol error
...
Offlist we figured it out:
If the "REGIAO" column field value is empty, then it fails. Perhaps
only happening with char columns. Somewhere here:
http://trac.osgeo.org/grass/browser/grass/branches/releasebranch_6_4/db/drivers/dbf/dbfexe.c#L644
My wild guess would be that the problem is rather in the cmp_row_asc
function, where you have on line 481:
case DBF_CHAR:
c1 = tbl->rows[*row1].values[cur_cmp_ocol].c;
c2 = tbl->rows[*row2].values[cur_cmp_ocol].c;
return (strcmp(c1, c2));
break;
Don't know how strcmp handles empty values. Maybe you could add something
like
fprinf(stdout, "c1 = %s, c2 = %s\n", a, b);
before the return statement to see the state of the respective character
variables ?
Very good :)
echo "SELECT cat, REGIAO FROM regiao ORDER BY REGIAO" | db.select
D0/0: c1 = ALTO PORTUGAL, c2 = ALTO PORTUGAL
D0/0: c1 = NOROESTE CISMONTANO, c2 = ALTO PORTUGAL
D0/0: c1 = NOROESTE CISMONTANO, c2 = ALTO PORTUGAL
D0/0: c1 = NOROESTE CISMONTANO, c2 = ALTO PORTUGAL
D0/0: c1 = (null), c2 = ALTO PORTUGAL
dbmi: Protocol error
BAD happens when Null is found here.
And that's arguably a correct behaviour as how should NULL be handled in
such a comparison ? Don't know how it is dealt with in other DBMS...
So, before we fix this in any way, we should probably agree to how to
handle it. One possible way would be to check for nulls and if there are
any to assign a return value according to our choice as to where to sort
nulls to. Don't know how to check for an uninitialised char variable in
C, but I imagine that it should be possible.
Moritz
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