Re: WIP: Avoid creation of the free space map for small tables - Mailing list pgsql-hackers

From Amit Kapila
Subject Re: WIP: Avoid creation of the free space map for small tables
Date
Msg-id CAA4eK1JPWRVyoT_vcPuE5+2Hrvecuc9u+RAg=JpkRExdq91dwQ@mail.gmail.com
Whole thread Raw
In response to Re: WIP: Avoid creation of the free space map for small tables  (John Naylor <jcnaylor@gmail.com>)
List pgsql-hackers
On Wed, Oct 31, 2018 at 1:42 PM John Naylor <jcnaylor@gmail.com> wrote:
>
> Upthread I wrote:
>
> > -A possible TODO item is to teach pg_upgrade not to link FSMs for
> > small heaps. I haven't look into the feasibility of that, however.
>
> This turned out to be relatively light weight (0002 attached). I had
> to add relkind to the RelInfo struct and save the size of each heap as
> its transferred. The attached SQL script will setup a couple test
> cases to demonstrate pg_upgrade. Installations with large numbers of
> small tables will be able to see space savings right away.
>
> For 0001, I adjusted the README and docs, and also made some cosmetic
> improvements to the code, mostly in the comments. I've set the
> commitfest entry back to 'needs review'
>
> One thing I noticed is that one behavior on master hasn't changed:
> System catalogs created during bootstrap still have a FSM if they have
> any data. Possibly related, catalogs also have a VM even if they have
> no data at all. This isn't anything to get excited about, but it would
> be nice to investigate, at least so it can be documented. A cursory
> dig hasn't found the cause, but I'll keep doing that as time permits.
>

Thanks for your work on this, I will try to review it during CF.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com


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