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Re: Strange explain on partitioned tables

От: Gerald Fontenay
Тема: Re: Strange explain on partitioned tables
Дата: ,
Msg-id: 4C4DFD95.4000901@lbl.gov
(см: обсуждение, исходный текст)
Ответ на: Re: Strange explain on partitioned tables  ("Joshua D. Drake")
Ответы: Re: Strange explain on partitioned tables  (Robert Haas)
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.

Joshua D. Drake
Thank you for your response. So if I query only my target child table, this should be "just like" any other single table wrt planning right? I have thousands of these tables. (I suppose that I'm only using inheritance for the sake of organization in this situation...)

Thanks!
Gerald

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