Re: Patch to add functionality to specify ORDER BY in CREATE FUNCTION for SRFs

On 06-01-2015 PM 04:00, Ashutosh Bapat wrote:
> On Tue, Jan 6, 2015 at 12:23 PM, Atri Sharma <atri.jiit@gmail.com> wrote:
>>> We can eliminate the new node and put onus or having the right order on
>>> the user like we do with volatile setting of the function.
>>>
>>>
>>
>> That is exactly what the new node does, since we are not re sorting right
>> now in case the order is wrong. Please see my explanation upthread,
>> OrderCheck node's primary purpose is to check for a user error in the
>> result rows order. The onus right now to give correct order is on user.
>>
>>
> Even checking whether the output of the function is in the right order or
> not, has its cost. I am suggesting that we can eliminate this cost as well.
> For example, PostgreSQL does not check whether a function is really
> immutable or not.
>

Sounds something like ORDERED BY x implying output is "known" ordered by
x perhaps enough hint for the planner to make necessary plan choices
though I may be wrong.