Re: WAL consistency check facility - Mailing list pgsql-hackers

From Amit Kapila
Subject Re: WAL consistency check facility
Date
Msg-id CAA4eK1LVLGF=53Odasq6Nv9rMbnbDsQ6VbGQR0QJMVJhg1iMnQ@mail.gmail.com
Whole thread Raw
In response to Re: WAL consistency check facility  (Kuntal Ghosh <kuntalghosh.2007@gmail.com>)
List pgsql-hackers
On Wed, Sep 7, 2016 at 3:52 PM, Kuntal Ghosh <kuntalghosh.2007@gmail.com> wrote:
>
> I got two types of inconsistencies as following:
>
> 1. For Btree/UNLINK_PAGE_META, btpo_flags are different. In backup
> page, BTP_DELETED and BTP_LEAF both the flags are set, whereas after
> redo, only BTP_DELETED flag is set in buffer page.
>

I see that inconsistency in code as well.  I think this is harmless,
because after the page is marked as deleted, it is not used for any
purpose other than to recycle it for re-use.  After re-using it, the
caller always suppose to initialize the flags based on it's usage and
I see that is happening in the code unless I am missing something.

> I assume that we
> should clear all btpo_flags before setting BTP_DELETED in
> _bt_unlink_halfdead_page().
>

Yeah, we can do that for consistency.  If we see any problem in doing
so, then I think we can log the flags and set them during replay.


Note - Please post your replies inline rather than top posting them.
It breaks the discussion link, if you top post it.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com



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