Re: Add visibility map information to pg_freespace.

On 20 June 2013 04:26, Satoshi Nagayasu <snaga@uptime.jp> wrote:
> I'm looking into this patch as a reviewer.
>
>
> (2013/06/19 18:03), Simon Riggs wrote:
>>
>> On 19 June 2013 09:19, Kyotaro HORIGUCHI
>> <horiguchi.kyotaro@lab.ntt.co.jp> wrote:
>>
>>> It should useful in other aspects but it seems a bit complicated
>>> just to know about visibility bits for certain blocks.
>>
>>
>> With your current patch you can only see the visibility info for
>> blocks in cache, not for all blocks. So while you may think it is
>> useful, it is also unnecessarily limited in scope.
>>
>> Let's just have something that is easy to use that lets us see the
>> visibility state for a block, not just blocks in freespace.
>
>
> I think we can have this visibility map statistics also
> in pgstattuple function (as a new column) for this purpose.
>
> IMHO, we have several modules for different purposes.
>
> - pageinspect provies several functions for debugging purpose.
> - pg_freespace provies a view for monitoring purpose.
> - pgstattuple provies several functions for collecting
>   specific table/index statistics.
>
> So, we can have similar feature in different modules.
>
> Any comments?

+1

--Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services