Horton

Re: Enable data checksums by default

Tomas Vondra <tomas@vondra.me>

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From: Tomas Vondra <tomas@vondra.me>
To: Peter Eisentraut <peter@eisentraut.org>, Nathan Bossart <nathandbossart@gmail.com>
Cc: Greg Sabino Mullane <htamfids@gmail.com>, Bruce Momjian <bruce@momjian.us>, Michael Paquier <michael@paquier.xyz>, Michael Banck <mbanck@gmx.net>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-04-22T22:24:39Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Avoid BufferGetLSNAtomic() calls during nbtree scans.

  2. doc PG 18 relnotes: Add incompatibility note about checksums now default

  3. Fix pg_upgrade's cross-version tests when old < 18

  4. initdb: Change default to using data checksums.

  5. Allow TAP tests to force checksums off when calling init()

  6. initdb: Add new option "--no-data-checksums"

  7. Tweak docs to reduce possible impact of data checksums

On 10/16/24 08:54, Peter Eisentraut wrote:
> On 14.10.24 11:28, Peter Eisentraut wrote:
>> On 03.10.24 23:13, Nathan Bossart wrote:
>>> On Tue, Oct 01, 2024 at 11:15:02AM -0400, Peter Eisentraut wrote:
>>>> I have committed 0001 (the new option) and 0004 (the docs tweak).  I
>>>> think
>>>> there is consensus for the rest, too, but I'll leave it for a few
>>>> more days
>>>> to think about.  I guess the test failure has to be addressed.
>>>
>>> Here is a rebased patch with the test fix (for cfbot).  I have made no
>>> other changes.
>>
>> I have committed the test changes (patch 0002).  (I renamed the option
>> to no_data_checksums to keep the wording consistent with the initdb
>> option.)
>>
>> Right now, with checksums off by default, this doesn't do much, but
>> you can test this like
>>
>>      PG_TEST_INITDB_EXTRA_OPTS=--data-checksums meson test ...
>>
>> and everything will pass.  To make that work, I had to adjust the
>> order of how the initdb options are assembled in Cluster.pm a bit.
>>
>> I will work on the patch that flips the default next.
> 
> The patch that flips the default has been committed.
> 
> I also started a PG18 open items page and made a note that we follow up
> on the upgrade experience, as was discussed in this thread.
> 
> https://wiki.postgresql.org/wiki/PostgreSQL_18_Open_Items
> 

Regarding the open item, can someone explain what exactly are we
planning to evaluate mid-beta?

We went through the open items on the RMT team meeting today, and my
impression was the questions are mostly about performance of having
checksums by default, but now I realize the thread talks about "upgrade
experience" which seems fairly wide.

So, what kind of data we expect to gather in order to evaluate this?
Who's expected to collect it and evaluate this?

regards

-- 
Tomas Vondra