Ah,
by looking at it, it would seems the store wrapper in the mosaic module is
not correctly
delegating down the visitor and thus breaking database optimizations.
Yep, pull requests are quite welcomed, please pay attention to the rules to
contribute,
detailed here:
https://github.com/geotools/geotools/blob/master/CONTRIBUTING.md
In particular, note code formatting (just running maven on the command
line will reformat the code as expected), presence of tests, and
contribution agreement
Cheers
Andrea
On Thu, Aug 9, 2018 at 6:30 PM György Tomcsányi <
gyorgy.tomcsa...@microstep-mis.com> wrote:
> Hello all,
>
> we are using GeoServer to display a large number of GeoTIFFs using
> ImageMosaic data stores. The data has several dimensions (time and
> custom). We are adding new data to these stores periodically and the
> goal is to be able to display years of data (millions of granules). We
> have encountered performance problems with the WMS GetCapabilities
> operation. It is most noticeable when using Oracle database (or PostGIS
> with parameter WrapStore=true). My colleague Ivan (in CC) implemented
> changes which improved the performance for our use case significantly.
> We would like to publish these changes and hopefully merge them into the
> official repo.
>
> Details:
> our performance problems are caused by the queries for values and
> defaults for dimensions. The currently used queries vary depending on
> the selected presentation for the dimension:
>
> 1. query for values:
> "List":
> * PostGIS (with WrapStore=false): SELECT distinct("<dim_name>")
> FROM "<table_name>"
> * Oracle: SELECT FID, <DIM_NAME> FROM <table_name>
> * PostGIS (with WrapStore=true): SELECT "fid","<dim_name>" FROM
> "<table_name>"
> First version is clearly the fastest, because it loads only
> distinct values.
>
> "Interval and resolution":
> The queries are the same as for "List", but in this case we only
> really need the min/max values, which could be calculated much faster in
> the database.
>
> 2. query for defaults (when using smallest/biggest domain value):
> * PostGIS (with WrapStore=false): SELECT <min | max> ("<dim_name>")
> FROM "<table_name>"
> * Oracle: SELECT FID, <DIM_NAME> FROM <table_name>
> * PostGIS (with WrapStore=true): SELECT "fid","<dim_name>" FROM
> "<table_name>"
> Again the first PostGIS variant is clearly the fastest. Others load
> all the values to the application where the min/max values are calculated.
>
> Our proposed solution creates optimized queries depending on which
> presentation and default setting is used for the dimension. The needed
> additional information from the settings is sent to the lower level
> functions using new RenderingHints. The goal of the optimized queries is
> to load only the needed values from the database (usually what the
> current PostGIS query does). Unit tests were also added.
>
> We would like to get some feedback on this. Can I submit merge requests
> (to both GeoTools and GeoServer) to review the code?
> We are looking forward to any comments.
>
> best regards,
> Gyorgy Tomcsanyi
>
>
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--
Regards, Andrea Aime == GeoServer Professional Services from the experts!
Visit http://goo.gl/it488V for more information. == Ing. Andrea Aime
@geowolf Technical Lead GeoSolutions S.A.S. Via di Montramito 3/A 55054
Massarosa (LU) phone: +39 0584 962313 fax: +39 0584 1660272 mob: +39 339
8844549 http://www.geo-solutions.it http://twitter.com/geosolutions_it
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