Re: TODO : Allow parallel cores to be used by vacuumdb [ WIP ]

On Fri, Jan 2, 2015 at 8:34 PM, Kevin Grittner <kgrittn(at)ymail(dot)com> wrote:
>
> Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> > Notes for Committer -
> > There is one behavioural difference in the handling of
--analyze-in-stages
> > switch, when individual tables (by using -t option) are analyzed by
> > using this switch, patch will process (in case of concurrent jobs) all
the
> > given tables for stage-1 and then for stage-2 and so on whereas in the
> > unpatched code it will process all the three stages table by table
> > (table-1 all three stages, table-2 all three stages and so on). I think
> > the new behaviour is okay as the same is done when this utility does
> > vacuum for whole database.
>
> IMV, the change is for the better. The whole point of
> --analyze-in-stages is to get minimal statistics so that "good
> enough" plans will be built for most queries to allow a production
> database to be brought back on-line quickly, followed by generating
> increasing granularity (which takes longer but should help ensure
> "best plan") while the database is in use with the initial
> statistics. Doing all three levels for one table before generating
> the rough statistics for the others doesn't help with that, so I
> see this change as fixing a bug. Is it feasible to break that part
> out as a separate patch?
>

Currently as the patch stands the fix (or new behaviour) is only
implemented for the multiple jobs option, however to fix this in base
code a separate patch is required.

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