[rrd-developers] implementing portable format - change format?

[Tobias Oetiker]

Igor,

my understanding is that even in the UPDATE case it is not a simple
value replacement that happens ... but I would be most interested
in your tests, stability and performance of such a solution ... you
can do this with mockup configs without actually re-writing
rrdtool.

cheers
tobi

Today Sfiligoi Igor wrote:

> Tobias Oetiker wrote:
> > Hi Igor,
> >
> > Yesterday Igor Sfiligoi wrote:
> >
> >> Hi Kevin and Tobi.
> >>
> >> Since you are planning to radically change the format, have you considered
> >> going a more "standard" way?
> >>
> >> Instead of having a completely RRDTool specific format, use something
> >> other tools could easily read?
> >>
> >> What about SQLite?
> >> It is already portable.
> >> And it is a database ;)
> >>
> >> It should be pretty easy to define a schema that serves RRDTool well.
> >>
> >> Would it be worth a consideration?
> >>
> >> Igor
> >
> > yes the thought has crossed my mind, the problem with SQL databases
> > is that they are not realy good at updating round robin archives,
> > du to transactional consistancy constraints they will create
> > internal fragmentation which will cause performance to suffer
> > dramatically.
> >
> > BUT it would be an interesting thought to see, if we can abstract
> > the interface enough so that writing a 'plugin' for an sqlite
> > storage backend becomes easy ...
> >
> > cheers
> > tobi
> What if the table had a structure like this:
> index,date,value(1,value2,...)
>
> with index the table key.
> I.e. very similar to what you have now in the RRD file.
>
> One would populate all the rows with consecutive indexes and
> date=NULL,valueX=NULL at creation time.
> The updates would be SQL UPDATEs on the existing row, i.e. replacing
> date+valueX at a specific index.
>
> No INSERTs, no DELETEs.
> This should keep the database compact and of fixed size.
>
> Do you still see a fragmentation problem under this conditions?
>
> Cheers,
>   Igor
>
>
>

-- 
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900