Re: prevent immature WAL streaming

On 2021-Sep-02, Kyotaro Horiguchi wrote:

> So, this is a crude PoC of that.

I had ended up with something very similar, except I was trying to cram
the flag via the checkpoint record instead of hacking
AdvanceXLInsertBuffer(). I removed that stuff and merged both, here's
the result.

> 1. This patch is written on the current master, but it doesn't
> interfare with the seg-boundary-memorize patch since it removes the
> calls to RegisterSegmentBoundary.

I rebased on top of the revert patch.

> 2. Since xlogreader cannot emit a log-message immediately, we don't
> have a means to leave a log message to inform recovery met an
> aborted partial continuation record. (In this PoC, it is done by
> fprintf:p)

Shrug. We can just use an #ifndef FRONTEND / elog(LOG). (I didn't keep
this part, sorry.)

> 3. Myebe we need to pg_waldump to show partial continuation records,
> but I'm not sure how to realize that.

Ah yes, we'll need to fix that.

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
"Las navajas y los monos deben estar siempre distantes" (Germán Poo)