Hi,
On 1/10/23 2:22 AM, Michael Paquier wrote:
On Mon, Jan 09, 2023 at 08:30:00AM +0530, Bharath Rupireddy wrote:
A recent commit [1] added --save-fullpage option to pg_waldump to
extract full page images (FPI) from WAL records and save them into
files (one file per FPI) under a specified directory. While it added
tests to check the LSN from the FPI file name and the FPI file
contents, it missed to further check the FPI contents like the tuples
on the page. I'm attaching a patch that basically reads the FPI file
(saved by pg_waldump) contents and raw page from the table file (using
pageinspect extension) and compares the tuples from both of them. This
test ensures that the pg_waldump outputs the correct FPI. This idea is
also discussed elsewhere [2].
Thoughts?
I am not sure that it is necessary to expand this set of tests to have
dependencies on heap and pageinspect (if we do so, what of index AMs)
and spend more cycles on that, while we already have something in
place to cross-check ReadRecPtr with what's stored in the page header
written on top of the block size.
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).
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
