Re: XLogBeginRead's header comment lies

On Wed, Aug 17, 2022 at 11:18 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Tue, Aug 16, 2022 at 11:28 PM Robert Haas <robertmhaas@gmail.com> wrote:
> >
>
> Yeah I think it makes sense to make it work as per the comment in
> XLogBeginRecord().  I think if we modify the Assert as per the comment
> of XLogBeginRecord() then the remaining code of the
> XLogDecodeNextRecord() is capable enough to take care of skipping the
> page header if we are pointing at the beginning of the block.
>
> See attached patch.
>

I think that is not sufficient, if there is a record continuing from
the previous page and we are pointing to the start of the page then
this assertion is not sufficient.  I think if the
targetRecOff is zero then we should additionally read the header and
verify that XLP_FIRST_IS_CONTRECORD is not set.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com