Hi,
On 12/27/22 12:48 PM, Bharath Rupireddy wrote:
Hi,
Here's a patch that implements the idea of extracting full page images
from WAL records [1] [2] with a function in pg_walinspect. This new
function accepts start and end lsn and returns full page image info
such as WAL record lsn, tablespace oid, database oid, relfile number,
block number, fork name and the raw full page (as bytea). I'll
register this in the next commitfest.
Thoughts?
I think it makes sense to somehow align the pg_walinspect functions with the pg_waldump
"features".
And since [1] added FPI "extraction" then +1 for the proposed patch in this
thread.
[1]
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=d497093cbecccf6df26365e06a5f8f8614b591c8
[2]
https://postgr.es/m/CAOxo6XKjQb2bMSBRpePf3ZpzfNTwjQUc4Tafh21=jzjx6bx...@mail.gmail.com
I just have a few comments:
+
+/*
+ * Get full page images and their info associated with a given WAL record.
+ */
What about adding a few words about compression? (like "Decompression is applied if
necessary"?)
+ /* Full page exists, so let's output it. */
+ if (!RestoreBlockImage(record, block_id, page))
"Full page exists, so let's output its info and content." instead?
+ <para>
+ Gets raw full page images and their information associated with all the
+ valid WAL records between <replaceable>start_lsn</replaceable> and
+ <replaceable>end_lsn</replaceable>. Returns one row per full page image.
Worth to add a few words about decompression too?
I'm also wondering if it would make sense to extend the test coverage of it (and
pg_waldump) to "validate" that both
extracted images are the same and matches the one modified right after the
checkpoint.
What do you think? (could be done later in another patch though).
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
