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From Jason Rutherglen <jason.rutherg...@gmail.com>
Subject Re: Count of keys of an FST
Date Thu, 28 Jun 2012 15:19:08 GMT
Thanks, it's done!  :)

https://issues.apache.org/jira/browse/CASSANDRA-4324

On Thu, Jun 28, 2012 at 9:36 AM, Dawid Weiss
<dawid.weiss@cs.put.poznan.pl>wrote:

> Let me know if you need that snippet of code to count the keys; or try
> it yourself -- should be good practice :)
>
> Dawid
>
> On Thu, Jun 28, 2012 at 3:32 PM, Jason Rutherglen
> <jason.rutherglen@gmail.com> wrote:
> > I looked at the sources and didn't see a key count.
> >
> > Thanks Dawid and Mike.
> >
> > On Thu, Jun 28, 2012 at 6:37 AM, Michael McCandless
> > <lucene@mikemccandless.com> wrote:
> >>
> >> I believe node and arc count are stored, but not key count.  But check
> >> the sources to be sure!
> >>
> >> Mike McCandless
> >>
> >> http://blog.mikemccandless.com
> >>
> >> On Wed, Jun 27, 2012 at 4:53 PM, Dawid Weiss
> >> <dawid.weiss@cs.put.poznan.pl> wrote:
> >> > If you need the count with constant time then yes, you should store it
> >> > separately. You could also make a transducer that would store it at
> >> > the root node as side-effect of values associated with keys, but it's
> >> > kind of ugly.
> >> >
> >> > Please check the fst header though -- I'm not sure, maybe Mike wrote
> >> > it so that the node count/ keys count is in there.
> >> >
> >> > Dawid
> >> >
> >> > On Wed, Jun 27, 2012 at 10:50 PM, Jason Rutherglen
> >> > <jason.rutherglen@gmail.com> wrote:
> >> >> Sounds like I should just count as the keys are added and store the
> >> >> count
> >> >> separately.
> >> >>
> >> >> On Wed, Jun 27, 2012 at 3:48 PM, Dawid Weiss
> >> >> <dawid.weiss@cs.put.poznan.pl>
> >> >> wrote:
> >> >>>
> >> >>> I don't think there is one that you could use out of the box...
but
> >> >>> maybe I'm wrong and it's stored in the header somewhere (don't
have
> >> >>> the source in front of me).
> >> >>>
> >> >>> To calculate it by hand the worst case is that you'll need a
> recursive
> >> >>> traversal, which would mean O(number of stored states) with
> >> >>> intermediate count caches or O(number of keys) without any caches
> and
> >> >>> memory overhead (just recursive traversal).
> >> >>>
> >> >>> Dawid
> >> >>>
> >> >>> On Wed, Jun 27, 2012 at 10:36 PM, Jason Rutherglen
> >> >>> <jason.rutherglen@gmail.com> wrote:
> >> >>> > The FST class has a number of methods that return counts,
which
> one
> >> >>> > returns
> >> >>> > the total number of keys that have been encoded into the FST?
> >> >>>
> >> >>>
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> >> >>
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> >
>
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