Re: CTE Materialization

Спасибо!
--
С уважением, Дмитрий!

ср, 8 дек. 2021 г. в 22:58, Paul van der Linden <paul(dot)doskabouter(at)gmail(dot)com
>:

> This one quite nicely explains it:
> https://stackoverflow.com/questions/14897816/how-can-i-prevent-postgres-from-inlining-a-subquery
>
> On Wed, Dec 8, 2021 at 3:14 AM David G. Johnston <
> david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>
>> On Tue, Dec 7, 2021 at 6:40 PM Дмитрий Иванов <firstdismay(at)gmail(dot)com>
>> wrote:
>>
>>> I beg your pardon.
>>> The problem is more or less clear to me, but the solution is not. What
>>> does the "hack is to add an "offset 0" to the query" suggest? Thank you.
>>>
>>>
>> A subquery with a LIMIT clause cannot have where clause expressions in
>> upper parts of the query tree pushed down it without changing the overall
>> query result - something the planner is not allowed to do. For the hack,
>> since adding an actual LIMIT clause doesn't make sense you omit it, but
>> still add the related OFFSET clause so the planner still treats the
>> subquery as a LIMIT subquery. And since you don't want to skip any rows
>> you specify 0 for the offset.
>>
>> David J.
>>
>>