[HACKERS] Returning the name of a primary key

[Juan Pablo Espino]

Hello all

I need to write a function that retrieve the name of at least one
table primary key, if it exists.  The only argument passed to the
function is the table name.  I have thought something like this:

char *
give_pkey(char * table_char)
        TupleDesc               tupdesc;
        Form_pg_attribute       att;
        Form_pg_index           ind;
        int                     i, c=0, temp=-1;

        tupdesc = (TupleDesc) RelationNameGetTupleDesc(tabla_char);

        ind = <<something that idicates which table is>>
        for (i=0; i<(tupdesc->natts); i++)
        {
            att = tupdesc->attrs[i];
            c = c + 1;

            /* Something that can compare each attribute to determine
if it is a primary key ?*/
            if ((ind->indisprimary) && (temp=-1))
            {
                 temp = c;
                 att = tupdesc->attrs[temp];
             }
          }
          return pstrdup(NameStr(att->attname));
}

Sorry, I don't have much experience in c programming, thanks in
advance for any suggestions, regards,

Juan P. Espino

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