Re: Sort a column that does not exist

Hi, I think I solved the problem in the parser and the planner, but I'm
stuck in the executor, I think is in the ExecSort function on nodeSort
around this code:

/*
* Scan the subplan and feed all the tuples to tuplesort.
*/

for (;;)
{
slot = ExecProcNode(outerNode);

if (TupIsNull(slot))
break;

tuplesort_puttupleslot(tuplesortstate, slot);
}

Now, when the server get in that loop it hangs out, Would I have to add
something that identifies the extra column? or will I have to include
somewhere in the tuplesort the column?

2009/4/2 Werner Echezuria <wercool(at)gmail(dot)com>

>
> Hi, the problem goes on. I think the problem is in the planner.c on
> grouping_planner function, because when I do a regular sort it gets to it:
>
> /*
> * 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))
> {
> result_plan = (Plan *) make_sort_from_pathkeys(root,
> result_plan,
> sort_pathkeys,
> limit_tuples);
> current_pathkeys = sort_pathkeys;
> }
> }
>
> and do the make_sort_from_pathkeys, but when I do the sort by grmemb it
> does not. So I change it in order to pass through make_sort_from_pathkey,
> but it drops an error like this "invalid attnum", so when I go to heaptuple
> and force to get to ObjectIdGetDatum in heap_getsysattr, the server hang
> out. What can I do? How can I assign a valid attrnum?
>
>
> 2009/4/1 Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
>
>> 2009/4/1 Werner Echezuria <wercool(at)gmail(dot)com>:
>>
>> > 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 the targetlist as a sort node. I know that it creates
>> the
>> > node on the parser, but it does not work, it seems the executor don't
>> see
>> > it.
>>
>> See include/nodes/primnodes.h around line 1075:
>> bool resjunk; /* set to true to eliminate
>> the attribute from
>> * final
>> target list */
>>
>> If the TargetEntry is set resjunk = false, the final result is
>> filtered as junk. So more accurately the executor sees but drops it.
>>
>> >
>> > How could I sort a column like this?, I know i'm missing something, but
>> i
>> > just don't see it. What is the process to sort a column?
>> >
>>
>> Use makeTargetEntry in makefuncs.c
>> TargetEntry *
>> makeTargetEntry(Expr *expr,
>> AttrNumber resno,
>> char *resname,
>> bool resjunk)
>>
>> by the 4th argument you can set resjunk = false if you don't want it
>> to be in the result.
>>
>> Regards,
>>
>>
>> --
>> Hitoshi Harada
>>
>
>