Re: ProjectSet

Поиск
Список
Период
Сортировка
От David Rowley
Тема Re: ProjectSet
Дата
Msg-id CAKJS1f9pWUwxaD+0kxOOUuwaBcpGQtCKi3DKE8ob_uHN-JTJhw@mail.gmail.com
обсуждение исходный текст
Ответ на ProjectSet  (Oliver Kohll <oliver@agilechilli.com>)
Ответы Re: ProjectSet  (Oliver Kohll <oliver@agilechilli.com>)
Список pgsql-general
On 2 August 2018 at 21:17, Oliver Kohll <oliver@agilechilli.com> wrote:
> Is there an explanation of ProjectSet anywhere?

Plan node types and what they each do are not very well documented
outside of the source code.

ProjectSet appears when the SELECT or ORDER BY clause of the query.
They basically just execute the set-returning function(s) for each
tuple until none of the functions return any more records.

Simple Example:

EXPLAIN SELECT generate_series(1,2);
                   QUERY PLAN
-------------------------------------------------
 ProjectSet  (cost=0.00..5.02 rows=1000 width=4)
   ->  Result  (cost=0.00..0.01 rows=1 width=0)
(2 rows)

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


В списке pgsql-general по дате отправления:

Предыдущее
От: ik
Дата:
Сообщение: Re: Adding terminal title support for psqlrc
Следующее
От: rihad
Дата:
Сообщение: ERROR: found xmin 54230249 from before relfrozenxid 61349053