Re: BUG #19616: pgoutput sends stream abort ('A') to clients that did not enable streaming

Dear Kuroda-san!

Thanks for the review.

I addressed both comments in the attached v3.

пт, 14 авг. 2026 г. в 08:03, Hayato Kuroda (Fujitsu) <
kuroda(dot)hayato(at)fujitsu(dot)com>:

> Dear Tyler, Andrey,
> (Adding Sawada-san in CC)
>
> Good catch and thanks for the report. I confirmed that your reproducer
> causes an
> Assert failure for the debug build. See:
>
> ```
> (gdb) bt
> #0 ReorderBufferMaybeMarkTXNStreamed (rb=0x3385430, txn=0x33a55a8)
> at ../postgres/src/backend/replication/logical/reorderbuffer.c:2154
> #1 0x0000000000973d05 in ReorderBufferTruncateTXN (rb=0x3385430,
> txn=0x33a5440,
> txn_prepared=false) at
> ../postgres/src/backend/replication/logical/reorderbuffer.c:1677
> #2 0x00000000009740ec in ReorderBufferCheckAndTruncateAbortedTXN
> (rb=0x3385430, txn=0x33a5440)
> at ../postgres/src/backend/replication/logical/reorderbuffer.c:1816
> #3 0x0000000000977aa1 in ReorderBufferCheckMemoryLimit (rb=0x3385430)
> at ../postgres/src/backend/replication/logical/reorderbuffer.c:3985
> #4 0x0000000000972345 in ReorderBufferQueueChange (rb=0x3385430, xid=696,
> lsn=24970056,
> change=0x33a8be0, toast_insert=false)
> ...
> ```
>
> Few comments for the code:
>
> ```
> + * A top-level transaction is always marked. A subtransaction is marked
> only
> + * when it has changes and its top-level transaction is already streamed.
> ```
>
> The last sentence can be "its top-level transaction is already marked as
> streamed."
>
> ```
> + /*
> + * A subtransaction is marked only when it has changes, and only
> when its
> + * top-level transaction has already been marked as streamed. We
> never
> + * stream XIDs of empty subxacts, and we must not send an abort
> for an XID
> + * the downstream has never heard of.
> *
> - * We do it this way because of aborts - we don't want to send
> aborts for
> - * XIDs the downstream is not aware of. And of course, it always
> knows
> - * about the top-level xact (we send the XID in all messages), but
> we
> - * never stream XIDs of empty subxacts.
> + * The top-level check matters because ReorderBufferTruncateTXN is
> also
> + * used to discard already-aborted transactions at eviction, where
> the
> + * top-level xact is not streamed. Marking a subxact there would
> make a
> + * later abort emit stream_abort to a client that never enabled
> streaming.
> */
> - if (rbtxn_is_toptxn(txn) || (txn->nentries_mem != 0))
> + if (txn->nentries_mem != 0 &&
> rbtxn_is_streamed(rbtxn_get_toptxn(txn)))
> ```
>
> I feel the code comment might be too detail: second paragraph is not needed
> for me.
>
> Best regards,
> Hayato Kuroda
> FUJITSU LIMITED
>
>

--
Regards,
Rachitskiy Andrey