Re: Make tuples_per_page pr. table configureable.

From: Jesper Krogh <jesper(at)krogh(dot)cc>
To: Itagaki Takahiro <itagaki(dot)takahiro(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Make tuples_per_page pr. table configureable.
Date: 2010-09-22 04:41:01
Message-ID: 4C9988DD.1000509@krogh.cc
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On 2010-09-22 04:33, Itagaki Takahiro wrote:
> On Wed, Sep 22, 2010 at 3:44 AM, Jesper Krogh<jesper(at)krogh(dot)cc> wrote:
>
>> Command to set "tuples_per_page" is:
>> ALTER TABLE<tablename> set (tuples_per_page = X)
>> where 1<= X<= 32.
>>
> The tuples_per_page means *minimal* number of tuples in a page, right?
> A page may contain more tuples when the size of tuples are small enough.
> If so, I think the parameter name is confusable because it sounds
> *restrict* the number of tuples per page like fillfactor.
> "min_tuples_per_page" might be better for the name.
>

Yes, minimum.. I'll change that. The name was picked to this since
it is the name of the variable in the source-code, but thats actully a
really bad argument by itself. min_tuples_per_page is more correct.
> I didn't read previous discussions, but did we have consensus that "number
> of tuples" is better than other units for the parameter? For example,
> "threshold bytes" or "percentage in a page" also seems to be reasonable for me.
>
I thought about chaning it to bytes, but my feeling was that it would
make most sense with something that would multiply to 8KB anyway
people wouldn't end up with 5KB and a table mostly filled with 3KB nothing
per page. So I tried to describe the "small math" in the documentation.

Thanks for you feedback.

--
Jesper

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