Re: [ROOT] TObject::Write(), purge and keys

From: Anton (anton.fokin@smartquant.com)
Date: Sun Apr 29 2001 - 19:34:09 MEST


Hi Rene,

at least it would be fine to have this feature in TDirectory::Purge();

- Keep N keys
- Keep keys newer than date

Otherwise as I said there is not much flexibility in cleaning out your file (I
mean with a simple ROOT call)

Moreover, combinations you have mentioned seem to be rather standard for
disk/file/object management. (Basically these are typical services of any
backup program. I have already forgotten VMS but as far as I remember you can
delete files for a range of dates, etc,  etc). Why don't you want to implement
them? They are quite generic for any application.

Regards,
Anton

Rene Brun wrote:

> Hi Anton,
>
> I suppose you mean "newer than" rather than "older than".
>
> One can imagine many combinations of service functions to keep or remove
> cycles for each key or/and all keys. The selections could be
>  - maximum number of cycles
>  - age
>  - time/date window
>  - object patterns
>  - key names
>  - etc.
>
> You can already make use of the function TKey::Keep to force a key
> to be kept (purge will not destroy it).
>
> I am open to suggestions, but I would not like to implement a plethore
> of functions too specific for one type of application only.
>
> The information in the TKey objects should be sufficient to easily
> trigger a selection in a simple iterator.
>
> Rene Brun
>
> On Sat, 28 Apr 2001, Anton wrote:
>
> > Hi rooters,
> >
> > I would like to have the following functionality in root:
> >
> > - setting a predefined number of circles to keep in root file on
> > TObject::Write()
> > - on new Write() save keys with dates older than a predefined date or
> > minus n days from today.
> >
> > I think it is easy to introduce. Otherwise we currently have only two
> > options - keep all copies of an object or keep the latest one (or set by
> > hand TKey::Keep() and call purge).
> >
> > It would also be nice to be able to recover a copy of object by date.
> >
> > I understand that this functionality is partly implemented in TKey etc.
> > but I would like to see a direct realization in TDirectory::Purge() and
> > TObject::Write()
> >
> > Regards,
> > Anton
> >



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