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https://issues.apache.org/jira/browse/JENA-1740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16917512#comment-16917512
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Greg Albiston commented on JENA-1740:
-------------------------------------
Additional contributions to the GeoSPARQL extension can be provided through a
pull request against the Apache Jena repo on GitHub.
A concern with storing large pieces of data in triplestores is that triples can
be accessed repeatedly during a query, e.g unbound variables. This means that
performance can suffer if the triple cannot be quickly processed and analysed.
When developing the GeoSPARQL, I found that the GeometryLiterals were being
accessed and decoded about 7 times when resolving a query, hence the short-term
caching that is applied.
It may be more prudent to use a hashing function, or similar, and store that as
the literal value in the triplestore. This can then be used to look up from a
filestore and return/manipulate the raster if required. This might mean having
a function that converts the hash literal into a raster literal for return from
a query.
It would seem that a seperate module is needed that can then depend upon the
GeoSPARQL module. Within that module the two (or more) groups of functions can
be loaded as required by the user.
> Extending Apache Jena with more geospatial functions
> ----------------------------------------------------
>
> Key: JENA-1740
> URL: https://issues.apache.org/jira/browse/JENA-1740
> Project: Apache Jena
> Issue Type: Improvement
> Reporter: Timo Homburg
> Priority: Minor
>
> Hello,
> I am the developer of a project which I named postgis-jena
> (https://github.com/i3mainz/postgis-jena), originally aimed at extending
> JenaARQ with query functions common in databases such as POSTGIS but now
> going beyond that approach and also integrating support for raster data
> (still WIP). I am building up work being done by Greg Albistons extension
> geosparql-jena.
> Is this extension of interest for Apache Jena as a plugin or in another
> context?
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