Re: Regression failures after changing PostgreSQL blocksize

Zhang Mingli <zmlpostgres@gmail.com> writes:
>> On Thu, Feb 12, 2026 at 7:19 AM Yasir <yasir.hussain.shah@gmail.com> wrote:
>>> This produced so many regression failures. I'm wondering, are such failures typical/expected when altering the
defaultblock size? 

> Our experience shows that when changing the block size, most of the regression test differences are expected — they
oftenreflect output variations (like buffer counts, cost estimates, or physical storage details) rather than functional
bugs.
> That said, it really needs to be examined case by case.

Indeed.  There is relevant documentation here:

https://www.postgresql.org/docs/current/regress-evaluation.html

(Some of that looks a bit out of date, ie differences we don't really
expect to happen anymore.  But plan changes and row-ordering changes
are definitely expected if you change any parameter that affects
planner cost estimates.)

            regards, tom lane