Re: Strange explain on partitioned tables

От: Gerald Fontenay
Тема: Re: Strange explain on partitioned tables
Дата: ,
Msg-id: 4C4A8851.3090608@lbl.gov
(см: обсуждение, исходный текст)
Ответ на: Re: Strange explain on partitioned tables  ("Joshua D. Drake")
Список: pgsql-performance

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Strange explain on partitioned tables  (Philippe Rimbault, )
 Re: Strange explain on partitioned tables  (Philippe Rimbault, )
  Re: Strange explain on partitioned tables  (Philippe Rimbault, )
 Re: Strange explain on partitioned tables  (Greg Smith, )
  Re: Strange explain on partitioned tables  (Philippe Rimbault, )
  Re: Strange explain on partitioned tables  (Gerald Fontenay, )
   Re: Strange explain on partitioned tables  ("Joshua D. Drake", )
    Re: Strange explain on partitioned tables  (Gerald Fontenay, )
    Re: Strange explain on partitioned tables  (Gerald Fontenay, )
     Re: Strange explain on partitioned tables  (Robert Haas, )
   Re: Strange explain on partitioned tables  (Greg Smith, )
   Re: Strange explain on partitioned tables  ("Joshua D. Drake", )

Joshua D. Drake wrote:
> On Fri, 2010-07-23 at 15:03 -0700, Gerald Fontenay wrote:
>
>>> The PostgreSQL partitioning system is aimed to support perhaps a
>>> hundred inherited tables.  You can expect to get poor performance on
>>> queries if you create 1000 of them.
>>>
>> Hi,
>>
>> Why is that you would expect poor performance for say 1000 or more? I
>> have a ~1000 inherited tables and I don't see any significant slowdowns.
>> I only ever access a single inherited table at a time though in this
>> situation. I suppose I am using inheritance only for organization in
>> this case...
>>
>
> It is variable based on workload and as I recall has to do with the
> planning time. As the number of children increases, so does the planning
> time.
>
>


 I do not execute queries against the parent and children tables.
It became obvious that this can be quite slow.
I am asking specifically if I can expect problems in *that* situation, again, where I directly query a single child
tableonly and where I may have thousands. Just like a any other single table query, no? 

Thank you,
Gerald





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