Sort a column that does not exist

Hi,<br /><br />I'm in a project that probably some of you have heart about, it is called PostgreSQLf and I get some
helpbefore from this list. The developer team is been doing some progress about. Now one of us has created an extra
columnthat is called membership degree, this performs some calculations over some data that it is store on a data
table.We just create a target entry on the parser and the planner, then in the ExecScan function is where the
calculationsperforms.<br /><br />Well, I have been assigned a task. I have to sort that target entry. I created this
targetentry on parse_clause and then I do this:<br /><br />List *<br />transformSortClause(ParseState *pstate,<br />   
               List *orderlist,<br />                     List **targetlist,<br />                    bool
resolveUnknown)<br/>{<br />    List       *sortlist = NIL;<br />    ListCell   *olitem;<br /><br />    foreach(olitem,
orderlist)<br/>    {<br />        SortBy       *sortby = lfirst(olitem);<br />         TargetEntry *tle;<br />       
//Tofind out if it is the membership degree<br />        char       *namegrmemb = strVal(linitial(((ColumnRef *)
sortby->node)->fields));<br/>        <br />        if (strcmp(namegrmemb, "grmemb")==0)<br />             tle =
createTargetFuzzyEntry(targetlist);<br/>        else<br />            tle = findTargetlistEntry(pstate,
sortby->node,<br/>                                      targetlist, ORDER_CLAUSE);<br /><br />        sortlist =
addTargetToSortList(pstate,tle,<br />                                        sortlist, *targetlist,<br />           
                          sortby->sortby_dir,<br />                                      
sortby->sortby_nulls,<br/>                                       sortby->useOp,<br />                            
          resolveUnknown);<br />        <br />        <br /><br />    }<br /><br />    return sortlist;<br />}<br /><br
/>//Tosort the membership degree<br />TargetEntry *<br />createTargetFuzzyEntry(List **targetlist){<br />     <br />   
/*Ijust have to create the fuzzy target entry right here */<br />    TargetEntry    *tfp = makeNode(TargetEntry);<br
/>   Const   *cn = makeNode(Const);<br />    float    val = 1.0;<br />    TargetEntry *tlast = list_nth(*targetlist,
list_length(*targetlist)-1);<br/><br />    cn = makeConst(700, -1, 4, (Float4GetDatum(val)), false, true); <br />   
tfp->resorigtbl=tlast->resorigtbl;<br/>    tfp->expr = (Expr *) cn;<br />    tfp->resno =
list_length(*targetlist)+ 1;<br />    tfp->resname = "grmemb";<br />     tfp->resorigcol =
list_length(*targetlist)+ 1;<br />    tfp->ressortgroupref = 0;<br />    tfp->resjunk = false;<br /><br />   
*targetlist= lappend(*targetlist, tfp);<br /><br />    return tfp;<br />}<br />As you can see if someone do this:
SELECT* FROM table WHERE field=some_value ORDER BY grmemb, postgresql creates a new target entry and then assigned to
thetargetlist as a sort node. I know that it creates the node on the parser, but it does not work, it seems the
executordon't see it.<br /><br />How could I sort a column like this?, I know i'm missing something, but i just don't
seeit. What is the process to sort a column?<br />