Re: Common Table Expressions (WITH RECURSIVE) patch

Hi,

2008/10/1 Dimitri Fontaine <dfontaine@hi-media.com>:
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> Hi,
>
> Le 30 sept. 08 à 20:03, Tom Lane a écrit :
>>
>>        set_read_position(tupstore, &local_read_position);
>>        tuple = tuplestore_gettuple(tupstore, ...);
>>        get_read_position(tupstore, &local_read_position);
>>
>> rather than just tuplestore_gettuple.  The set/get functions will be
>> cheap enough that this is no big deal.  (Or maybe we should just
>> provide a wrapper function that does this sequence?)
>
> It seems to me to share some ideas with the MemoryContext concept: what
> about a TupstoreContext associated with tuplestore, you get a common default
> one if you don't register your own, and use
>        tuplestore_gettuple(MyTupstoreContext, ...);
>
> Maybe some other API would benefit from the idea?
>

I'm just working on tuplestore recording multiple positions for my
window function project. Attached patch is still in progress but seems
it works in a situation.

>From my work, the setting/getting read position and delegate savig
positions to the caller will probably have problems, because of memory
control for saving positions and tuplestore status changing (memory ->
BufFile). Instead, I decided it'd better that we can indicate the row
number by integer.

Regards,

--
Hitoshi Harada