Horton

Thread

Commits

  1. doc: Tweak sentence for pg_checksums when enabling checksums

  1. clarify "rewritten" in pg_checksums docs

    Michael Banck <michael.banck@credativ.de> — 2020-09-01T13:13:58Z

    Hi,

the pg_checksums docs mention that "When enabling checksums, every file
in the cluster is rewritten".

From IRC discussions, "rewritten" seems ambiguous, it could mean that a
second copy of the file is written and then switched over, implying
increased storage demand during the operation.

So maybe "rewritten in-place" is better, as per the attached?


Michael

-- 
Michael Banck
Projektleiter / Senior Berater
Tel.: +49 2166 9901-171
Fax:  +49 2166 9901-100
Email: michael.banck@credativ.de

credativ GmbH, HRB Mönchengladbach 12080
USt-ID-Nummer: DE204566209
Trompeterallee 108, 41189 Mönchengladbach
Geschäftsführung: Dr. Michael Meskes, Jörg Folz, Sascha Heuer

Unser Umgang mit personenbezogenen Daten unterliegt
folgenden Bestimmungen: https://www.credativ.de/datenschutz

  2. Re: clarify "rewritten" in pg_checksums docs

    Daniel Gustafsson <daniel@yesql.se> — 2020-09-01T13:29:17Z

    > On 1 Sep 2020, at 15:13, Michael Banck <michael.banck@credativ.de> wrote:

> the pg_checksums docs mention that "When enabling checksums, every file
> in the cluster is rewritten".
> 
> From IRC discussions, "rewritten" seems ambiguous, it could mean that a
> second copy of the file is written and then switched over, implying
> increased storage demand during the operation.

Makes sense, I can see that confusion.

> So maybe "rewritten in-place" is better, as per the attached?

Isn't "modified in-place" a more accurate description of the process?

cheers ./daniel

  3. Re: clarify "rewritten" in pg_checksums docs

    Michael Banck <michael.banck@credativ.de> — 2020-09-01T13:34:11Z

    Hi,

Am Dienstag, den 01.09.2020, 15:29 +0200 schrieb Daniel Gustafsson:
> > On 1 Sep 2020, at 15:13, Michael Banck <michael.banck@credativ.de> wrote:
> > the pg_checksums docs mention that "When enabling checksums, every file
> > in the cluster is rewritten".
> > 
> > From IRC discussions, "rewritten" seems ambiguous, it could mean that a
> > second copy of the file is written and then switched over, implying
> > increased storage demand during the operation.
> 
> Makes sense, I can see that confusion.
> 
> > So maybe "rewritten in-place" is better, as per the attached?
> 
> Isn't "modified in-place" a more accurate description of the process?

AIUI we do rewrite the whole file (block by block, after updating the
page header with the checksum), so yeah, I though about using modified
instead but then decided rewritten is pretty (or even more) accurate.


Michael

-- 
Michael Banck
Projektleiter / Senior Berater
Tel.: +49 2166 9901-171
Fax:  +49 2166 9901-100
Email: michael.banck@credativ.de

credativ GmbH, HRB Mönchengladbach 12080
USt-ID-Nummer: DE204566209
Trompeterallee 108, 41189 Mönchengladbach
Geschäftsführung: Dr. Michael Meskes, Jörg Folz, Sascha Heuer

Unser Umgang mit personenbezogenen Daten unterliegt
folgenden Bestimmungen: https://www.credativ.de/datenschutz

  4. Re: clarify "rewritten" in pg_checksums docs

    Daniel Gustafsson <daniel@yesql.se> — 2020-09-01T13:44:06Z

    > On 1 Sep 2020, at 15:34, Michael Banck <michael.banck@credativ.de> wrote:
> Am Dienstag, den 01.09.2020, 15:29 +0200 schrieb Daniel Gustafsson:

>> Isn't "modified in-place" a more accurate description of the process?
> 
> AIUI we do rewrite the whole file (block by block, after updating the
> page header with the checksum), so yeah, I though about using modified
> instead but then decided rewritten is pretty (or even more) accurate.

Well, I was thinking less technically accurate and more descriptive for end
users, hiding the implementation details.  "Rewrite" sounds to me more like
changing data rather than amending pages with a checksum keeping data intact.
Either way, adding "in-place" is an improvement IMO.

cheers ./daniel

  5. Re: clarify "rewritten" in pg_checksums docs

    Michael Paquier <michael@paquier.xyz> — 2020-09-02T08:26:16Z

    On Tue, Sep 01, 2020 at 03:44:06PM +0200, Daniel Gustafsson wrote:
> Well, I was thinking less technically accurate and more descriptive for end
> users, hiding the implementation details.  "Rewrite" sounds to me more like
> changing data rather than amending pages with a checksum keeping data intact.
> Either way, adding "in-place" is an improvement IMO.

Using rewritten still sounds more adapted to me, as we still write the
thing with chunks of size BLCKSZ.  No objections with the addition of
"in-place" for that sentence.  Any extra opinions?
--
Michael

  6. Re: clarify "rewritten" in pg_checksums docs

    Michael Paquier <michael@paquier.xyz> — 2020-09-07T06:00:20Z

    On Wed, Sep 02, 2020 at 05:26:16PM +0900, Michael Paquier wrote:
> Using rewritten still sounds more adapted to me, as we still write the
> thing with chunks of size BLCKSZ.  No objections with the addition of
> "in-place" for that sentence.  Any extra opinions?

Seeing no objections, I have applied the original patch of this thread
down to 12.
--
Michael