Re: Proposal: Limitations of palloc inside checkpointer

Hi, Xuneng Zhou!

On Tue, Apr 15, 2025 at 7:02 AM Xuneng Zhou <xunengzhou@gmail.com> wrote:
> I've moved this entry to the July CommitFest. The CI reported an unused variable warning in patch v5, so I've
addressedit by removing the unused one. Sorry for not catching the issue locally. 

Thank you for your work on this subject!

I have few notes about that:
1) Should we make CompactCheckpointerRequestQueue() process the queue
of checkpoint requests in smaller parts for the same reason we do this
in AbsorbSyncRequests()? That would require significant redesign of
the algorithm, but still.
2) That's pretty independent to the changes by the patch, but should
CompactCheckpointerRequestQueue() fill the gaps with entries from the
tail instead of rewriting the whole queue?  That might be a bit
faster.
3) For sure, we wouldn't backpatch this.  Can we prepare some simple
solution for back branches?  Perhaps, just introduction of
MAX_CHECKPOINT_REQUESTS is enough to save us from allocations larger
than 1GB.

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Regards,
Alexander Korotkov
Supabase