Re: Online index builds

Ühel kenal päeval, L, 2006-07-15 kell 21:10, kirjutas Greg Stark:
> Hannu Krosing <hannu@skype.net> writes:
> 
> > Maybe we can show progress indicators in status line (either
> > pg_stat_activity.current_query or commandline shown in ps), like 
> > 
> > WAITING TO START PHASE 1 - WAITING FOR TRANSACTION XXX TO COMPLETE 
> > 
> > or 
> > 
> > INSERTING INDEX ENTRY N OF M
> > 
> > changing every few seconds.
> 
> Hm. That would be very interesting. I'll say that one of the things that
> impressed me very much with Postgres moving from Oracle was the focus on
> usability. Progress indicators would be excellent for a lot of operations.
> 
> That said I'm not sure how much I can do here. For a substantial index we
> should expect most of the time will be spent in the tuplesort.

If index is substantially bigger than shared memory/available RAM then
tuple by tuple index insertion part can also be quite slow and i/o
consuming even if the number of entries to insert is low compared to
total index size. That is where "INSERTING INDEX ENTRY N OF M" would be
a thing which helps the DBA to estimate time to completion.

> It's hard to
> see how to get any sort of progress indicator out of there and as long as we
> can't it's hard to see the point of getting one during the heap scan or any of
> the other i/o operations.

It would be useful to know, in what step we are in general , that is are
we doing some useful work or just waiting for "something".


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Hannu Krosing
Database Architect
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