Hi,
Thanks for the prompt reply!
On 09/07/2025 08:37, Bertrand Drouvot wrote:
Yeah, I tried to avoid code duplication for the "os pages" related stuff in
v1. I can check if more can be done (outside of the "os pages" related stuff).
Might be done in a dedicated patch though, I mean I don't think that should be
a blocker for this one.
Agreed, if there's any low-hanging fruit to address now that this file is cracked open, then great. Otherwise, makes sense to leave it for a separate dedicated patch.
If you don't mind I have some further questions on the patch, see below.
+ if (get_call_result_type(fcinfo, NULL, &expected_tupledesc) != TYPEFUNC_COMPOSITE)
+ elog(ERROR, "return type must be a row type");
Is this needed in the new pg_buffercache_os_pages function? I noticed this check also in the "original" pg_buffercache_pages. There's a comment there indicating that (if I understand correctly) its purpose is to handle upgrades from version 1.0, mentioning a field unrelated to this patch.
If it's needed, shall we consider adding a similar comment as in pg_buffercache_pages?
+ /*
+ * Different database block sizes (4kB, 8kB, ..., 32kB) can be used,
+ * while the OS may have different memory page sizes.
+ *
+ * To correctly map between them, we need to: 1. Determine the OS
+ * memory page size 2. Calculate how many OS pages are used by all
+ * buffer blocks 3. Calculate how many OS pages are contained within
+ * each database block.
+ */
For step number 3 - should it be the other way around: database blocks are contained within OS pages?
Kind regards,
Mircea Cadariu
