New types in binary ?

We are developping a GIS system using PG as database.

We could create multiple geographic type in PG: point, line, polygon,... but
we would like to try something else.

We want to use this structure in creating a new PG type (extending PG type
in C)

typedef struct {
    int4    size;          /* for postgresql and us                 */
    int4    type;          /* The type of object NONE, POINT, etc.  */
    float8  bound[2][3];   /* bounding box -- min(x,y,z) max(x,y,z) */
    char    data[1];       /* Resizable variable type data          */
} geoobj;

The geobj->data would contain the binary representation of various
structures:

typedef struct {
    int4 type=1;
    float x,y,z
} point

typedef struct {
    int4 type=2;
    float x1,y1,z1,x2,y2,z2;
} line

and so on...

We could write functions that will convert the various structures into an
ascii stream for display in PG:

select geoobj from table
"POINT [x,y,z]" , "LINE [x1,y1,z1][x2,y2,z2]"

But we would like also the data pushed in pure binary. We could use a
function to ensure we want the binary value of the type

Select XDR(geoobj) from table
<binarystuff>

We will then take the binary stuff stored in a char and we will cast it to
the right structure. Do you think it will work and PG will not jump to the
roof because of binary stream output as a char* ?

BTW it will create a varbinary type that is waiting to be toasted.

Cheers.

Franck Martin
Database Development Officer
SOPAC South Pacific Applied Geoscience Commission
Fiji
E-mail: franck@sopac.org.fj <mailto:franck@sopac.org.fj>
Web site: http://www.sopac.org.fj/ <http://www.sopac.org.fj/>