Re: Why need XLogReadBuffer have the paramter "init"?

Oh, I am wrong!

"Jacky Leng" <lengjianquan(at)163(dot)com>
news:evk3gj$i94$1(at)news(dot)hub(dot)org(dot)(dot)(dot)
>
> "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> news:15998(dot)1176303488(at)sss(dot)pgh(dot)pa(dot)us(dot)(dot)(dot)
> > "Jacky Leng" <lengjianquan(at)163(dot)com> writes:
> > > Cann't we remove this param?
> >
> > No.
> >
> > > We can rewrite like this:
> > > 1.XLogReadBuffer:
> > > * remove init;
> > > * everytime we cann't read a block, just "log_invalid_page" it, and
> return
> > > InvalidBuffer;
> >
> > Your proposal degrades the robustness of the system by turning non-error
> > cases into errors. If the caller is able to rewrite the page fully, we
> > should not report an error when it's not available to read.
>
> Oh, I see, but how about my second question, is it possible?
> If it happens:
> 1. the second rel's pages' lsn surely is lager than xlog records of the
> first rel;
> 2. so it's possible some xlog record are not redoed;
> 3. but those pages that can be rewrite fully are rewrited unconditionaly,
>
> If I do a PITR recovery now, is there any trouble?----The file contains
both
> old rels'data and new rel's.
>
>
> Am I wrong?
>
>