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

Oh, I am wrong!


"Jacky Leng" <lengjianquan@163.com> д���ʼ�
news:evk3gj$i94$1@news.hub.org...
>
> "Tom Lane" <tgl@sss.pgh.pa.us> д���ʼ�
> news:15998.1176303488@sss.pgh.pa.us...
> > "Jacky Leng" <lengjianquan@163.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?
>
>