Re: [netconf] restconf collections

[Martin Björklund <[e-mail]>]

Kent Watsen <[e-mail]> wrote:
> Hi Qin,
> 
> > Some opstate must be persisted, e.g., long-lived counters, logs, etc.,
> > but it’s a good point about other opstate not being persisted.
> > Perhaps “node-tags” can be used here, to differentiate which is
> > which…and servers can indicate if/how they support the ephemeral
> > opstate leafs in queries?
> > 
> > [Qin]:That's a good case for node tag, in earlier discussion, we
> > discussed operation type, which distinguishs cumulative statistics
> > value from current value. The case discussed here is very close to
> > operation type proposal discussed earlier.
> 
> Yes.  Thank you for pointing that out.  I meant to make the same
> observation before.  Indeed, such node-tags could have dual-purpose:
> to guide a streaming-strategy and a querying-strategy for certain
> nodes.
> 
> 
> > Note sure how others feel about “direction: (c), but my primary
> > use-case revolves around time-series data (e.g., logs), where the
> > interest is commonly on the most-recent entries, so
> > "reverse-->offset—>limit” works nicely.
> > 
> > Perhaps an alternative would be to lift a concept from Python with
> > negative indexes so, for instance, offset=-N and limit=-N gives the
> > last N entries?
> > [Qin]: Yes, that's what I thought as well, with negative indexes, (b)
> > and (c) seems to me, can be combined.
> 
> Can others comment on this?

Isn't this just another syntax for the same function?


/martin


> Presumably, we could eliminate “direction” (c) with this approach.  
> 
> Without “direction”, I think that UIs can still support the ability to
> do column-sorts, whereby the user clicks on a column’s header to
> toggle ascending vs. descending presentation, but they’ll have to do
> it client-side.
> 
> That is, if wanting to see the 2nd page of results sorted by a column,
> something like:
> 
> 	sort(column-name) --> offset(-2*pagesize) --> limit(pagesize)
> 
> Followed by the client then flipping the results to present the
> results in the user-selected order, right?
> 
> That said, given that DB-backends that support sorts commonly also
> support direction, it's unclear what this buys us.
> 
> 
> >>> Sure, but I wonder if, e.g., a netmask filter, is supportable by 
> >>> common DB-backends.  I’m hoping we have some DB-experts on the list!
> >> 
> >> See above.  It can be quite efficient even if the backend doesn't 
> >> support it.
> > 
> > I don’t see that above, but I don’t doubt that it can be so, it’s just
> > a whole lot of implementation complexity.  It seems that we
> > should/must support servers doing it, we just need to find a way
> > (node-tags?) to enable them to express that ability.
> > [Qin]: My feeling is this efficiency more depends on the amount of
> > data we need to request. If amount of data we request is huge, maybe,
> > client-> server-> backend may be the better choice.
> 
> Is it the amount of data requested or the number of entries in the
> list?  At least, in my worldview, clients are always requesting a
> “page” of data, so that part is rather consistently small.
> 
> If the intention is to get a complete dump, then maybe the comment
> from yesterday applies, whereby streaming to an external repository
> that can be queried offline makes more sense?  - especially
> considering that the number of on-box logs is likely to be only the
> most recent (e.g., days), whereas the complete-dump type queries
> likely wish to extend well-past that.
> 
> K.
> 
>