[hibernate-dev] Coordinates storage in Lucene index for spatial functionality

Mon May 14 17:53:00 EDT 2012

>
> maybe even simpler set a constant as the seed of your random
> generator: should provide a reproducible sequence of values.

/facepalm
I should have guess that :s

Niko


>  >>
> >> On 11 May 2012 08:40, Nicolas Helleringer <
> nicolas.helleringer at gmail.com>
> >> wrote:
> >> > There, back and again ...
> >> >
> >> > After fixing a bug in grid search here are some updated results on 2k
> >> > calls
> >> >
> >> > Degrees :
> >> > Mean time with Grid : 4.4897266425641025 ms. Average number of docs
> >> >  fetched
> >> > : 2506.96
> >> > Mean time with Grid + Distance filter : 6.4930799487179485 ms. Average
> >> > number of docs  fetched : 425.33435897435896
> >> > Mean time with DoubleRange : 14.430638703076923 ms. Average number of
> >> > docs
> >> >  fetched : 542.0410256410256
> >> > Mean time with DoubleRange + Distance filter : 20.483300545128206 ms.
> >> > Average number of docs  fetched : 425.33435897435896
> >> >
> >> > Radians :
> >> > Mean time with Grid : 5.650845744102564 ms. Average number of docs
> >> >  fetched
> >> > : 5074.830769230769
> >> > Mean time with Grid + Distance filter : 8.627138825128204 ms. Average
> >> > number
> >> > of docs  fetched : 426.7902564102564
> >> > Mean time with DoubleRange : 15.337755502564102 ms. Average number of
> >> > docs
> >> >  fetched : 1087.705641025641
> >> > Mean time with DoubleRange + Distance filter : 20.82852138769231 ms.
> >> > Average
> >> > number of docs  fetched : 426.7902564102564
> >> >
> >> > Next thing I do not explain yet is the distance filter overhead
> mismatch
> >> > :
> >> > It is less on grid search with more docs to test than on DoubleRange.
> >> >
> >> > Niko
> >> >
> >> >
> >> > 2012/5/7 Nicolas Helleringer <nicolas.helleringer at gmail.com>
> >> >>
> >> >> Here are some results :
> >> >>
> >> >> Mean time with Grid : 4.9297471630769225 ms. Average number of docs
> >> >>  fetched : 2416.373846153846
> >> >> Mean time with Grid + Distance filter : 6.48634534 ms. Average number
> >> >> of
> >> >> docs  fetched : 425.84
> >> >> Mean time with DoubleRange : 15.39593650051282 ms. Average number of
> >> >> docs
> >> >>  fetched : 542.72
> >> >> Mean time with DoubleRange + Distance filter : 21.158394677435897 ms.
> >> >> Average number of docs  fetched : 425.8779487179487
> >> >>
> >> >> Sounds weird that with distance filter the two results are note the
> >> >> same.
> >> >> I shall investigate that.
> >> >>
> >> >> Niko
> >> >>
> >> >> 2012/5/7 Emmanuel Bernard <emmanuel at hibernate.org>
> >> >>>
> >> >>> Do you know the average amount of POI that were filtered in memory
> but
> >> >>> the DistanceFilter during these runs?
> >> >>>
> >> >>> Emmanuel
> >> >>>
> >> >>> On 7 mai 2012, at 10:31, Nicolas Helleringer wrote:
> >> >>>
> >> >>> Hi all,
> >> >>>
> >> >>> I have done a radian patch/branch and some benchmarks on geonames
> >> >>> french
> >> >>> database.
> >> >>>
> >> >>> Benchs are on 2k calls each run.
> >> >>>
> >> >>> Radians:
> >> >>> run 1
> >> >>> Mean time with Grid : 4.808043092820513 ms
> >> >>> Mean time with Grid + Distance filter : 6.571108878461538 ms
> >> >>> Mean time with DoubleRange : 14.62661525128205 ms
> >> >>> Mean time with DoubleRange + Distance filter : 20.143597923076925 ms
> >> >>>
> >> >>> run 2
> >> >>> Mean time with Grid : 5.290368523076923 ms
> >> >>> Mean time with Grid + Distance filter : 6.706567517435897 ms
> >> >>> Mean time with DoubleRange : 14.878960702564102 ms
> >> >>> Mean time with DoubleRange + Distance filter : 20.75806591948718 ms
> >> >>>
> >> >>> Degrees:
> >> >>> run 1
> >> >>> Mean time with Grid : 5.101956610769231 ms
> >> >>> Mean time with Grid + Distance filter : 6.548685109230769 ms
> >> >>> Mean time with DoubleRange : 14.767478146153845 ms
> >> >>> Mean time with DoubleRange + Distance filter : 20.668063972820512 ms
> >> >>>
> >> >>> run 2
> >> >>> Mean time with Grid : 4.683360031282051 ms
> >> >>> Mean time with Grid + Distance filter : 6.7065247435897435 ms
> >> >>> Mean time with DoubleRange : 14.617140157948716 ms
> >> >>> Mean time with DoubleRange + Distance filter : 20.074868595897435 ms
> >> >>>
> >> >>> The radian branch is here for review
> >> >>>
> >> >>> :
> https://github.com/nicolashelleringer/hibernate-search/tree/HSEARCH-923-RADIANS
> >> >>>
> >> >>> While moving from degrees to radians I have seen that DSL has still
> >> >>> some
> >> >>> work to do.
> >> >>> I shall focus on that now.
> >> >>>
> >> >>> Niko
> >> >>>
> >> >>> 2012/5/3 Sanne Grinovero <sanne at hibernate.org>
> >> >>>>
> >> >>>>
> >> >>>> On May 3, 2012 10:10 AM, "Emmanuel Bernard" <
> emmanuel at hibernate.org>
> >> >>>> wrote:
> >> >>>> >
> >> >>>> > How comes the DistanceFilter has to compute the distance for the
> >> >>>> > whole
> >> >>>> > corpus?
> >> >>>>
> >> >>>> You're right in that's not always the case, but it's possible. If
> >> >>>> there
> >> >>>> are more filters enabled and they are executed first, our filter
> will
> >> >>>> need
> >> >>>> to do the math only on the matched documents by the previous
> filters,
> >> >>>> but if
> >> >>>> there are no other constraints or filters our DistanceFilter might
> >> >>>> need to
> >> >>>> process all documents in all segments. This happens also when a
> limit
> >> >>>> is
> >> >>>> enabled on the collector - although limited to the current index
> >> >>>> segment -
> >> >>>> when the filter needs to be cached as it needs to evaluate each
> >> >>>> document in
> >> >>>> the segment.
> >> >>>>
> >> >>>> In our case this DistanceFilter is only applied after RangeQuery
> was
> >> >>>> applied on both longitude and latitude, so I'm not sure if this is
> a
> >> >>>> big
> >> >>>> problem; personally I was just wondering but I'd be fine in keeping
> >> >>>> this as
> >> >>>> a possible future improvement - but if we go for a separate issue,
> >> >>>> let's
> >> >>>> keep in mind that that the index format would not be backwards
> >> >>>> compatible.
> >> >>>>
> >> >>>>
> >> >>>>
> >> >>>> > By the way the actual storage (say via Hibernate ORM, or
> >> >>>> > Infinispan)
> >> >>>> > does not need to store in radian, so we don't need to do a
> >> >>>> > conversion when
> >> >>>> > reading an entity.
> >> >>>>
> >> >>>> Right, another reason to index only in whatever format makes
> querying
> >> >>>> more efficient.
> >> >>>>
> >> >>>> -- Sanne
> >> >>>>
> >> >>>>
> >> >>>> >
> >> >>>> > On 3 mai 2012, at 10:45, Sanne Grinovero wrote:
> >> >>>> >
> >> >>>> > > The reason for my comment is that the code is doing a
> conversion
> >> >>>> > > to
> >> >>>> > > radians in the DistanceFilter, which needs to be extremely
> >> >>>> > > efficient
> >> >>>> > > as it's not only applied on the resultset but potentially on
> the
> >> >>>> > > whole
> >> >>>> > > corpus of all Documents in the index.
> >> >>>> > > So even if it's true that conversion would be needed on the
> final
> >> >>>> > > results, we always expect people to retrieve only a limited
> >> >>>> > > amount
> >> >>>> > > of
> >> >>>> > > entities (like with pagination), while the index might need to
> >> >>>> > > perform
> >> >>>> > > this computation millions of times per query.
> >> >>>> > >
> >> >>>> > > If I look at the complexity of Point.getDistanceTo(double,
> >> >>>> > > double),
> >> >>>> > > I
> >> >>>> > > get a feeling that that method will hardly provide speedy
> queries
> >> >>>> > > because of the complex computations in it - this is just
> >> >>>> > > speculation
> >> >>>> > > at this point of course, to be sure we'd need to compare them
> >> >>>> > > with a
> >> >>>> > > large enough dataset, but it seems quite obvious that storing
> >> >>>> > > normalized radians should be more efficient as it would avoid a
> >> >>>> > > good
> >> >>>> > > deal of math to be executed on each Document in the index.
> >> >>>> > >
> >> >>>> > > Also if we assume people might want to use radians in their
> user
> >> >>>> > > data
> >> >>>> > > (I know some who definitely would never touch decimals for
> such a
> >> >>>> > > use
> >> >>>> > > case), there would be no need at all to convert the end result.
> >> >>>> > >
> >> >>>> > > Some more thoughts inline:
> >> >>>> > >
> >> >>>> > > On 3 May 2012 09:12, Nicolas Helleringer
> >> >>>> > > <nicolas.helleringer at gmail.com> wrote:
> >> >>>> > >> Hi all,
> >> >>>> > >>
> >> >>>> > >> Sanne and I have been wondering about the way the spatial
> >> >>>> > >> branch/module/functionality for Hibernate Search shall store
> its
> >> >>>> > >> coordinates in the Lucene index.
> >> >>>> > >>
> >> >>>> > >> Today it is implemented with decimal degree for :
> >> >>>> > >> - easy debugging/readability
> >> >>>> > >> - ease of conversion on storage as we want to accept mainly
> >> >>>> > >> decimal
> >> >>>> > >> degree
> >> >>>> > >> from users data
> >> >>>> > >
> >> >>>> > > Valid points, but consider that "storage" is going to be way
> >> >>>> > > slower
> >> >>>> > > anyway, and typically you'll process a Document to evaluate it
> >> >>>> > > for a
> >> >>>> > > hit many many orders of magnitude more frequently than the
> times
> >> >>>> > > you
> >> >>>> > > store it.
> >> >>>> > >
> >> >>>> > >>
> >> >>>> > >> Sanne pointed out that when the search is done there is quite
> a
> >> >>>> > >> few
> >> >>>> > >> conversion to radians for distance calculation and suggested
> >> >>>> > >> that
> >> >>>> > >> we may
> >> >>>> > >> store directly coordinates under their radians form.
> >> >>>> > >>
> >> >>>> > >> I have tried a patch to implement this and as I was coding it
> I
> >> >>>> > >> feel that
> >> >>>> > >> the code was less readable, in the coordinates normalisation
> >> >>>> > >> mainly
> >> >>>> > >> and
> >> >>>> > >> that there was as many conversion as before.
> >> >>>> > >> Conversions had moved from search to import / export of
> >> >>>> > >> coordinates
> >> >>>> > >> in and
> >> >>>> > >> out the spatial module scope to user scope.
> >> >>>> > >
> >> >>>> > > I'm sure the amount of points in the code in which they are
> >> >>>> > > converted
> >> >>>> > > won't change. I'm concerned about the cardinality of the
> >> >>>> > > collections
> >> >>>> > > on which it's applied ;)
> >> >>>> > > "Less readable" isn't nice, but we can work on that I guess?
> >> >>>> > >
> >> >>>> > >>
> >> >>>> > >> What the docs does not tell (yet), is that we are waiting for
> >> >>>> > >> WGS
> >> >>>> > >> 84 (this
> >> >>>> > >> is a coordinate system) decimal degree coordinates input, as
> >> >>>> > >> these
> >> >>>> > >> are
> >> >>>> > >> quite a de facto standard (GPS output this way).
> >> >>>> > >
> >> >>>> > > How does it affect this?
> >> >>>> > >
> >> >>>> > >>
> >> >>>> > >> Today this is not the purpose of Hibernate Search spatial
> >> >>>> > >> initiative to
> >> >>>> > >> handle projections. There are opensource libs to handle that
> on
> >> >>>> > >> user side
> >> >>>> > >> very well (Proj4j)
> >> >>>> > >>
> >> >>>> > >> So. The question is : shall we store as radians or decimal
> >> >>>> > >> degree ?
> >> >>>> > >>
> >> >>>> > >> Niko
> >> >>>> > >>
> >> >>>> > >> P.S : Hope it is clear. If not ask for more.
> >> >>>> > >
> >> >>>> > > Thanks!
> >> >>>> > > Sanne
> >> >>>> > > _______________________________________________
> >> >>>> > > hibernate-dev mailing list
> >> >>>> > > hibernate-dev at lists.jboss.org
> >> >>>> > > https://lists.jboss.org/mailman/listinfo/hibernate-dev
> >> >>>> >
> >> >>>
> >> >>>
> >> >>>
> >> >>
> >> >
> >
> >
>