Re: Index corruption with CREATE INDEX CONCURRENTLY

2017-02-05 7:54 GMT+01:00 Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>:

>
> On Sat, Feb 4, 2017 at 11:54 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
>>
>> Based on Pavan's comments, I think trying to force this into next week's
>> releases would be extremely unwise. If the bug went undetected this long,
>> it can wait for a fix for another three months.
>
>
> Yes, I think bug existed ever since and went unnoticed. One reason could
> be that the race happens only when the new index turns HOT updates into
> non-HOT updates. Another reason could be that we don't have checks in place
> to catch these kinds of corruption. Having said that, since we have
> discovered the bug, at least many 2ndQuadrant customers have expressed
> worry and want to know if the fix will be available in 9.6.2 and other
> minor releases. Since the bug can lead to data corruption, the worry is
> justified. Until we fix the bug, there will be a constant worry about using
> CIC.
>
> If we can have some kind of band-aid fix to plug in the hole, that might
> be enough as well. I tested my first patch (which will need some polishing)
> and that works well AFAIK. I was worried about prepared queries and all,
> but that seems ok too. RelationGetIndexList() always get called within
> ExecInitModifyTable. The fix seems quite unlikely to cause any other side
> effects.
>
> Another possible band-aid is to throw another relcache invalidation in
> CIC. Like adding a dummy index_set_state_flags() within yet another
> transaction. Seems ugly, but should fix the problem for now and not cause
> any impact on relcache mechanism whatsoever.
>
> That seems better than
>> risking new breakage when it's barely 48 hours to the release wrap
>> deadline. We do not have time to recover from any mistakes.
>>
>
> I'm not sure what the project policies are, but can we consider delaying
> the release by a week for issues like these? Or do you think it will be
> hard to come up with a proper fix for the issue and it will need some
> serious refactoring?
>

I agree with Pavan - a release with known important bug is not good idea.

Pavel

> Thanks,
> Pavan
>
> --
> Pavan Deolasee http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Training & Services
>