Horton

Re: Enable data checksums by default

Jakub Wartak <jakub.wartak@enterprisedb.com>

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From: Jakub Wartak <jakub.wartak@enterprisedb.com>
To: Greg Sabino Mullane <htamfids@gmail.com>
Cc: Michael Banck <mbanck@gmx.net>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2024-08-15T07:49:04Z
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 Wed, Aug 7, 2024 at 4:18 PM Greg Sabino Mullane <htamfids@gmail.com> wrote:
>
> On Wed, Aug 7, 2024 at 4:43 AM Michael Banck <mbanck@gmx.net> wrote:
>>
>> I think the last time we dicussed this the consensus was that
>> computational overhead of computing the checksums is pretty small for
>> most systems (so the above change seems warranted regardless of whether
>> we switch the default), but turning on wal_compression also turns on
>> wal_log_hints, which can increase WAL by quite a lot. Maybe this is
[..]
>
>
> Yeah, that seems something beyond this patch? Certainly we should mention wal_compression in the release notes if the default changes. I mean, I feel wal_log_hints should probably default to on as well, but I've honestly never really given it much thought because my fingers are trained to type "initdb -k". I've been using data checksums for roughly a decade now. I think the only time I've NOT used checksums was when I was doing checksum overhead measurements, or hacking on the pg_checksums program.

Maybe I don't understand something, but just to be clear:
wal_compression (mentioned above) is not turning wal_log_hints on,
just the wal_log_hints needs to be on when using data checksums
(implicitly, by the XLogHintBitIsNeeded() macro). I suppose Michael
was thinking about the wal_log_hints earlier (?)

-J.