Re: Undo logs

Exciting stuff! Really looking forward to having a play with this.

James Sewell,
*Chief Architect*

Suite 112, Jones Bay Wharf, 26-32 Pirrama Road, Pyrmont NSW 2009
*P *(+61) 2 8099 9000 <(+61)%202%208099%209000> *W* www.jirotech.com *F *
(+61) 2 8099 9099 <(+61)%202%208099%209000>

On 25 May 2018 at 08:22, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> wrote:

> Hello hackers,
>
> As announced elsewhere[1][2][3], at EnterpriseDB we are working on a
> proposal to add in-place updates with undo logs to PostgreSQL. The
> goal is to improve performance and resource usage by recycling space
> better.
>
> The lowest level piece of this work is a physical undo log manager,
> which I've personally been working on. Later patches will build on
> top, adding record-oriented access and then the main "zheap" access
> manager and related infrastructure. My colleagues will write about
> those.
>
> The README files[4][5] explain in more detail, but here is a
> bullet-point description of what the attached patch set gives you:
>
> 1. Efficient appending of new undo data from many concurrent
> backends. Like logs.
> 2. Efficient discarding of old undo data that isn't needed anymore.
> Like queues.
> 3. Efficient buffered random reading of undo data. Like relations.
>
> A test module is provided that can be used to exercise the undo log
> code paths without needing any of the later zheap patches.
>
> This is work in progress. A few aspects are under active development
> and liable to change, as indicated by comments, and there are no doubt
> bugs and room for improvement. The code is also available at
> github.com/EnterpriseDB/zheap (these patches are from the
> undo-log-storage branch, see also the master branch which has the full
> zheap feature). We'd be grateful for any questions, feedback or
> ideas.
>
> [1] https://amitkapila16.blogspot.com/2018/03/zheap-storage-
> engine-to-provide-better.html
> [2] https://rhaas.blogspot.com/2018/01/do-or-undo-there-is-no-vacuum.html
> [3] https://www.pgcon.org/2018/schedule/events/1190.en.html
> [4] https://github.com/EnterpriseDB/zheap/tree/undo-
> log-storage/src/backend/access/undo
> [5] https://github.com/EnterpriseDB/zheap/tree/undo-
> log-storage/src/backend/storage/smgr
>
> --
> Thomas Munro
> http://www.enterprisedb.com
>

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