| Actually, I thought, I did this using the int32 variable called "dimension" which should be exactly this field. Unfortunately, it seems, that something is wrong here. I'll look inside the code of cube to determine the things I'm doing wrong, currently. Thanks so far for your advice. My in-method is the following: Datum pointnd_in(PG_FUNCTION_ARGS) { PointND * in = NULL; // access the format string char * in_string = PG_GETARG_CSTRING(0); char * save = in_string; // 1024 bytes should be sufficient for one coordinate char curr_buffer[1024]; bool corrupted = false; float8 * coordinates = NULL; unsigned int dimensions = 0, i = 0; coordinates = (float8 *) palloc(sizeof(float8)); // allocate the memory // read bytewise and count the ',' in order to determine the amount of dimensions, after that: parse the point in_string = find_char(in_string, '('); // next sign after opening bracket ++in_string; // read as long, as no closing bracket has been found for (dimensions = 0; *in_string != ')' && !corrupted; ++dimensions) { // clear the memory memset(curr_buffer, 0, 1024); for (i = 0; *in_string != ',' && *in_string != 0 && *in_string != ')'; ++in_string, ++i) { if ((*in_string < '0' || *in_string > '9') && *in_string != '.') { corrupted = true; break; } // copy current sign curr_buffer[i] = *in_string; } // something has happened here (no valid number) if (corrupted) { break; } coordinates = (float8 *) repalloc(coordinates, (dimensions + 1) * sizeof(float8)); //sscanf(curr_buffer, "%f", &coordinates[dimensions]); coordinates[dimensions] = strtod(curr_buffer, NULL); // if we have a comma here, skip it if (*in_string == ',') { ++in_string; } if (*in_string == ' ') { // skip space ++in_string; } } // something lead to a corruption of the point if (corrupted) { ereport(ERROR, (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), errmsg("invalid representation of a point: %s, has to look like \"(<coord1>,<coord2>,...)\"", save))); } else { in = (PointND *) palloc(sizeof(float8) * dimensions + VARHDRSZ); SET_VARSIZE(in, dimensions); // copy the coordinates to the data area memcpy((void *) VARDATA(in), (void *) coordinates, (dimensions) * sizeof(float8)); } PG_RETURN_POINTER(in); } So, probably in here, I am doing something terribly wrong and you could correct me at this point. As I already said, I thought that my int32 dimensions variable would represent exactly this vl_len_header field. The remaining stuff is OK then? That means the creation script and information about storage alignment and layout or do you detect addititonal errors? I know, that this code might not be the best, but I am still in the testing phase of how to achieve sth using Postgres with C. Thanks so far for your advice Best regards Carsten Kropf Am 10.02.2010 um 11:39 schrieb Yeb Havinga:
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