Re: Questions on query planner, join types, and work_mem
От | Tom Lane |
---|---|
Тема | Re: Questions on query planner, join types, and work_mem |
Дата | |
Msg-id | 22961.1280944836@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: Questions on query planner, join types, and work_mem (Hannu Krosing) |
Ответы |
Re: Questions on query planner, join types, and work_mem
(Hannu Krosing)
Re: Questions on query planner, join types, and work_mem (Bruce Momjian) |
Список | pgsql-performance |
Дерево обсуждения
Questions on query planner, join types, and work_mem
(Peter Hussey,
)
Re: Questions on query planner, join types, and work_mem (Andres Freund, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Alvaro Herrera, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Jayadevan M, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Peter Hussey, )
Re: Questions on query planner, join types, and work_mem (Robert Haas, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Robert Haas, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Greg Smith, )
Re: Questions on query planner, join types, and work_mem (Greg Smith, )
Re: Questions on query planner, join types, and work_mem ("Kevin Grittner", )
Re: Questions on query planner, join types, and work_mem (Greg Smith, )
Re: Questions on query planner, join types, and work_mem ("Kevin Grittner", )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem ("Kevin Grittner", )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Bruce Momjian, )
Re: Questions on query planner, join types, and work_mem (Robert Haas, )
Re: Questions on query planner, join types, and work_mem (Bruce Momjian, )
Re: Questions on query planner, join types, and work_mem (Bruce Momjian, )
Re: Questions on query planner, join types, and work_mem ("Kevin Grittner", )
Re: Questions on query planner, join types, and work_mem (Greg Smith, )
Re: Questions on query planner, join types, and work_mem (Andres Freund, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Alvaro Herrera, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Jayadevan M, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Peter Hussey, )
Re: Questions on query planner, join types, and work_mem (Robert Haas, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Robert Haas, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Greg Smith, )
Re: Questions on query planner, join types, and work_mem (Greg Smith, )
Re: Questions on query planner, join types, and work_mem ("Kevin Grittner", )
Re: Questions on query planner, join types, and work_mem (Greg Smith, )
Re: Questions on query planner, join types, and work_mem ("Kevin Grittner", )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Tom Lane, )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem ("Kevin Grittner", )
Re: Questions on query planner, join types, and work_mem (Hannu Krosing, )
Re: Questions on query planner, join types, and work_mem (Bruce Momjian, )
Re: Questions on query planner, join types, and work_mem (Robert Haas, )
Re: Questions on query planner, join types, and work_mem (Bruce Momjian, )
Re: Questions on query planner, join types, and work_mem (Bruce Momjian, )
Re: Questions on query planner, join types, and work_mem ("Kevin Grittner", )
Re: Questions on query planner, join types, and work_mem (Greg Smith, )
Hannu Krosing <> writes: > Of course there are more variables than just *_page_cost, so if you nail > down any other one, you may end with less than 1 for both page costs. > I have always used seq_page_cost = 1 in my thinking and adjusted others > relative to it. Right, seq_page_cost = 1 is sort of the traditional reference point, but you don't have to do it that way. The main point here is that for an all-in-RAM database, the standard page access costs are too high relative to the CPU effort costs: regression=# select name, setting from pg_settings where name like '%cost'; name | setting ----------------------+--------- cpu_index_tuple_cost | 0.005 cpu_operator_cost | 0.0025 cpu_tuple_cost | 0.01 random_page_cost | 4 seq_page_cost | 1 (5 rows) To model an all-in-RAM database, you can either dial down both random_page_cost and seq_page_cost to 0.1 or so, or set random_page_cost to 1 and increase all the CPU costs. The former is less effort ;-) It should be noted also that there's not all that much evidence backing up the default values of the cpu_xxx_cost variables. In the past those didn't matter much because I/O costs always swamped CPU costs anyway. But I can foresee us having to twiddle those defaults and maybe refine the CPU cost model more, as all-in-RAM cases get more common. regards, tom lane
В списке pgsql-performance по дате отправления:
Предыдущее
От: "Kevin Grittner"Дата:
Сообщение: Re: Questions on query planner, join types, and work_mem
Следующее
От: Hannu KrosingДата:
Сообщение: Re: Questions on query planner, join types, and work_mem