Thanks a lot so far. I adopted my structures and am now storing two fields
(v_len_ and dimensions) and the storage is now working properly. If I now would
try to combine two of these points to a range (like cube) including an upper
and a lower bound n-dimensional point structure, I don't get the point how to
achieve this.
I tried around a little bit and ended up with a structure like the following:
/**
* basic structure definition for a range containing an upper and a lower point
(in multiple dimensions)
*/
struct Range
{
int32 v_len_;
/**
* the upper limit in each dimension
*/
struct PointND * upper;
/**
* the lower limit in each dimension
*/
struct PointND * lower;
};
However, the problem is again, how to put this range into a table. Actually, I
don't know exactly, how to do this, I tried the following:
len = VARSIZE(upper) + VARSIZE(lower) + VARHDRSZ + 2 *
sizeof(struct Point *);
result = (Range *) palloc0(len);
// result->upper = upper;
// result->lower = lower;
memcpy((void *) result->upper, (void *) upper, VARSIZE(upper));
memcpy((void *) result->lower, (void *) lower, VARSIZE(lower));
// set the var size
SET_VARSIZE(result, len);
But this didn't do the trick. I did not yet find sth in the code of postgres,
how to build such a combined type, unfortunately (or I did not look at the
right places until now). How would one do this?
Thanks in advance
regards
Carsten Kropf
Am 10.02.2010 um 12:20 schrieb Yeb Havinga:
> Carsten Kropf wrote:
>> Oh, I see, does the VARSIZE length field have to be the total number of
>> bytes occupied (including VARHDRSZ and the size of the structure) or only
>> the size that is used by "my" datatype?
> Yes
>> Then it would become pretty much obvious, why this is not supposed to work.
>> I'll try it out then.
>>
> My €0,02: rename the dimensions to vl_len_ to avoid confusion and get
> compiler errors where you now use 'dimension'. Add a macro that converts a
> pointnd structure to dimension int by taking the VARSIZE_ANY_EXHDR /
> sizeof(float8) and use it where dimension is used now. Or if your database is
> small you could keep dimension in the structure.
>
>
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