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Re: Strange explain on partitioned tables

From: Gerald Fontenay <gvfontenay(at)lbl(dot)gov>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Strange explain on partitioned tables
Date: 2010-07-24 06:29:37
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
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 table only and where I may have thousands. Just like a any other single table query, no?

Thank you,

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