Re: Strengthen pg_waldump's --save-fullpage tests

Hi,

On 1/11/23 5:17 AM, Bharath Rupireddy wrote:
> On Wed, Jan 11, 2023 at 6:32 AM Michael Paquier <michael@paquier.xyz> wrote:
>>
>> On Tue, Jan 10, 2023 at 05:25:44PM +0100, Drouvot, Bertrand wrote:
>>> I like the idea of comparing the full page (and not just the LSN) but
>>> I'm not sure that adding the pageinspect dependency is a good thing.
>>>
>>> What about extracting the block directly from the relation file and
>>> comparing it with the one extracted from the WAL? (We'd need to skip the
>>> first 8 bytes to skip the LSN though).
>>
>> Byte-by-byte counting for the page hole?  

I've in mind to use diff on the whole page (minus the LSN).

>> The page checksum would
>> matter as well,

Right, but the TAP test is done without checksum and we could also
skip the checksum from the page if we really want to.

> Right. LSN of FPI from the WAL record and page from the table won't be
> the same, essentially FPI LSN <= table page. 

Right, that's why I proposed to exclude it for the comparison.

What about something like the attached?

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
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