Re: [HACKERS] ANALYZE command progress checker

On 3/1/17 1:25 PM, Andres Freund wrote:
> On 2017-03-01 10:20:41 -0800, David Fetter wrote:
>> On Wed, Mar 01, 2017 at 09:45:40AM -0500, Peter Eisentraut wrote:
>>> On 2/28/17 04:24, vinayak wrote:
>>>> The view provides the information of analyze command progress details as 
>>>> follows
>>>> postgres=# \d pg_stat_progress_analyze
>>>>            View "pg_catalog.pg_stat_progress_analyze"
>>>
>>> Hmm, do we want a separate "progress" system view for every kind of
>>> command?  What if someone comes up with a progress checker for CREATE
>>> INDEX, REINDEX, CLUSTER, etc.?
> 
> I don't think that'd be that bad, otherwise the naming of the fields is
> complicated.  I guess the alternative (or do both?) would be to to have
> a pivoted table, but that'd painful to query.  Do you have a better idea?
> 
> 
>> Some kind of design for progress seems like a good plan.  Some ideas:
>>
>> - System view(s)
>>
>>     This has the advantage of being shown to work at least to a PoC by
>>     this patch, and is similar to extant system views like
>>     pg_stat_activity in the sense of capturing a moment in time.
>>
>> - NOTIFY
>>
>>     Event-driven model as opposed to a polling one.  This is
>>     attractive on efficiency grounds, less so on reliability ones.
>>
>> - Something added to the wire protocol
>>
>>     More specialized, limits the information to the session where the
>>     command was issued
>>
>> - Other things not named here
> 
> We now have a framework for this [1] (currently used by vacuum, but
> extensible). The question is about presentation.  I'm fairly sure that
> we shouldn't just add yet another framework, and I doubt that that's
> what's proposed by Peter.

I think the idea of a general progress view is very valuable and there
are a ton of operations it could be used for:  full table scans, index
rebuilds, vacuum, copy, etc.

However, I feel that this proposal is not flexible enough and comes too
late in the release cycle to allow development into something that could
be committed.

I propose we move this to the 2017-07 CF so the idea can be more fully
developed.

-- 
-David
david@pgmasters.net