On Wed, Jun 19, 2024 at 05:14:50AM +0000, Hayato Kuroda (Fujitsu) wrote:
> I have an unclear point. According to the comment atop GetInsertRecPtr(), it just
> returns the approximated value - the position of the last full WAL page [1].
> If there is a continuation WAL record which across a page, will it return the
> halfway point of the WAL record (end of the first WAL page)? If so, the proposed
> fix seems not sufficient. We have to point out the exact the end of the record.
Yeah, that a thing of the patch I am confused with. How are we sure
that this is the correct LSN to rely on? If that it the case, the
patch does not offer an explanation about why it is better.
WalSndWaitForWal() is called only in the context of page callback for a
logical WAL sender. Shouldn't we make the flush conditional on what's
stored in XLogReaderState.missingContrecPtr? Aka, if we know that
we're in the middle of the decoding of a continuation record, we
should wait until we've dealt with it, no?
In short, I would imagine that WalSndWaitForWal() should know more
about XLogReaderState is doing. But perhaps I'm missing something.
--
Michael