Re: SLRUs in the main buffer pool, redux

Hi Thomas,

While I was working on adding the page headers to SLRU pages on your patch, I came across this code where it seems like "MultiXactIdToMemberPage" is mistakenly being used instead of MultiXactIdToOffsetPage in the TrimMultiXact function.

Below is the area of concern in the patch:

@@ -2045,14 +1977,7 @@ TrimMultiXact(void)
oldestMXactDB = MultiXactState->oldestMultiXactDB;
LWLockRelease(MultiXactGenLock);

- /* Clean up offsets state */
- LWLockAcquire(MultiXactOffsetSLRULock, LW_EXCLUSIVE);
-
- /*
- * (Re-)Initialize our idea of the latest page number for offsets.
- */
- pageno = MultiXactIdToOffsetPage(nextMXact);
- MultiXactOffsetCtl->shared->latest_page_number = pag0eno;
+ pageno = MXOffsetToMemberPage(offset);

Let us know if I am missing something here or if it is an error.

Sincerely,

Rishu Bagga (Amazon Web Services)

On 9/16/22, 5:37 PM, "Thomas Munro" <thomas(dot)munro(at)gmail(dot)com> wrote:

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Rebased, debugged and fleshed out a tiny bit more, but still with
plenty of TODO notes and questions. I will talk about this idea at
PGCon, so I figured it'd help to have a patch that actually applies,
even if it doesn't work quite right yet. It's quite a large patch but
that's partly because it removes a lot of lines...