Well, I do a query like this: "SELECT * FROM historial WHERE
id_grupo=grupo_hist ORDER BY grmemb LIMIT 10;", then in transformSortClause
I know it this way:
/*
* transformSortClause -
* transform an ORDER BY clause
*
* ORDER BY items will be added to the targetlist (as resjunk columns)
* if not already present, so the targetlist must be passed by reference.
*/
List *
transformSortClause(ParseState *pstate,
List *orderlist,
List **targetlist,
bool resolveUnknown)
{
List *sortlist = NIL;
ListCell *olitem;
foreach(olitem, orderlist)
{
SortBy *sortby = lfirst(olitem);
TargetEntry *tle;
//To find out if it is the membership degree
char *namegrmemb = strVal(linitial(((ColumnRef *)
sortby->node)->fields));
*if (strcmp(namegrmemb, "grmemb")==0)
* tle = createTargetFuzzyEntry(targetlist);
else
tle = findTargetlistEntry(pstate, sortby->node,
targetlist, ORDER_CLAUSE);
sortlist = addTargetToSortList(pstate, tle,
sortlist, *targetlist,
sortby->sortby_dir,
sortby->sortby_nulls,
sortby->useOp,
resolveUnknown);
}
return sortlist;
}
|***************************************************************************************************************************|
Then I created a function that includes a new target entry in the
targetlist:
//To sort the membership degree
TargetEntry *
createTargetFuzzyEntry(List **targetlist){
/*I just have to create the fuzzy target entry right here */
TargetEntry *tfp = makeNode(TargetEntry);
Const *cn = makeNode(Const);
float val = 1.0;
TargetEntry *tlast = list_nth(*targetlist, list_length(*targetlist)-1);
cn = makeConst(700, -1, 4, (Float4GetDatum(val)), false, true);
tfp->resorigtbl=tlast->resorigtbl;
tfp->expr = (Expr *) cn;
tfp->resno = list_length(*targetlist) + 1;
tfp->resname = "grmemb";
tfp->resorigcol = list_length(*targetlist) + 1;
tfp->ressortgroupref = 0;
tfp->resjunk = false;
*targetlist = lappend(*targetlist, tfp);
return tfp;
}
|*************************************************************************************************************************|
Later in planner.c on grouping_planner function I do something like this:
/*
* If we were not able to make the plan come out in the right order, add
* an explicit sort step.
*/
if (parse->sortClause)
{
if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys) ||
parse->hasGrMemb)
{
result_plan = (Plan *) make_sort_from_pathkeys(root,
result_plan,
sort_pathkeys,
limit_tuples);
current_pathkeys = sort_pathkeys;
}
}
2009/4/26 Martijn van Oosterhout <klep...@svana.org>
> On Sun, Apr 26, 2009 at 04:20:41PM -0430, Werner Echezuria wrote:
> > Hi, I've been trying to sort a column that performs some calculations,
> but
> > postgres says this: ERROR: invalid attnum: -12851. I was searching on
> the
> > source code, and I guess the error araises around this macro:
>
> I'm pretty sure this is a "not supposed to happen" thing. Do you have a
> repoducable test case? Also, what version of postgres?
>
> > /*
> > * Copy the given tuple into memory we control, and decrease
> availMem.
> > * Then call the common code.
> > */
> > COPYTUP(state, &stup, (void *) slot);
> >
> > So, I'd like to know what COPYTUP does?, what is availMem?, How can I
> tell
> > postgres it is a valid attnum?
>
> COPYTUP does exactly what the comment says it does. I'm guessing this
> is in the sort code somewhere? An "attnum" is a column number, like the
> first column is attnum 1. Attnum -12851 is definitly bogus.
>
> Have a nice day,
> --
> Martijn van Oosterhout <klep...@svana.org> http://svana.org/kleptog/
> > Please line up in a tree and maintain the heap invariant while
> > boarding. Thank you for flying nlogn airlines.
>
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