Re: TOAST usage setting

Tom Lane wrote:
> Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> > Whereas if you set toast_tuples_per_page to 8k then the only option for
> > Postgres will be to put each datum in its own page and waste 1-3k on every
> > page.
>
> No, because actually the code is designed to make the toast chunk size
> just enough less than 8K that the tuples fit.
>
> The shorter-than-normal tuples carrying the last chunk of any particular
> datum are going to result in wasted space to the extent that we can't
> pack them together on a page, but that's true now. Right now, if you
> have a large toasted datum, it mostly will consist of just-under-2K
> tuples that are sized so that there's no noticeable wasted space on a
> page with 4 of them. There isn't any advantage to that compared to one
> just-under-8K tuple AFAICS, and it takes 4 times as much work to insert
> or retrieve 'em.

Uh, am I supposed to be running more TOAST tests? Would someone explain
what they want tested?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com

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