Re: corruption of WAL page header is never reported

[Ranier Vilela]

Em sáb., 17 de jul. de 2021 às 16:57, Yugo NAGATA <nag...@sraoss.co.jp>
escreveu:

> Hello,
>
> I found that any corruption of WAL page header found during recovery is
> never
> reported in log messages. If wal page header is broken, it is detected in
> XLogReaderValidatePageHeader called from  XLogPageRead, but the error
> messages
> are always reset and never reported.
>
>         if (!XLogReaderValidatePageHeader(xlogreader, targetPagePtr,
> readBuf))
>         {
>                /* reset any error XLogReaderValidatePageHeader() might
> have set */
>                xlogreader->errormsg_buf[0] = '\0';
>                goto next_record_is_invalid;
>         }
>
> Since the commit 06687198018, we call XLogReaderValidatePageHeader here so
> that
> we can check a page header and retry immediately if it's invalid, but the
> error
> message is reset immediately and not reported. I guess the reason why the
> error
> message is reset is because we might get the right WAL after some retries.
> However, I think it is better to report the error for each check in order
> to let
> users know the actual issues founded in the WAL.
>
> I attached a patch to fix it in this way.
>
I think to keep the same behavior as before, is necessary always run:

/* reset any error XLogReaderValidatePageHeader() might have set */
xlogreader->errormsg_buf[0] = '\0';

not?

regards,
Ranier Vilela

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index edb15fe58d..4fdb23f061 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -12297,8 +12297,13 @@ retry:
 	 */
 	if (!XLogReaderValidatePageHeader(xlogreader, targetPagePtr, readBuf))
 	{
+		if (StandbyMode && xlogreader->errormsg_buf[0] != '\0')
+		{
+			ereport(emode_for_corrupt_record(emode, EndRecPtr),
+					(errmsg_internal("%s", xlogreader->errormsg_buf) /* already translated */ ));
+		}
		/* reset any error XLogReaderValidatePageHeader() might have set */
		xlogreader->errormsg_buf[0] = '\0';
 		goto next_record_is_invalid;
 	}