Hi Andrea
Le 16/04/2021 à 17:05, Andrea Aime a écrit :
Hi Erwan,
databases are not the only source of data. A function must be able to
work in memory first, so that it works
with shapefiles, elasticsearch, mongo and so on as well. Then there
can be an optimization translating
them down to SQL.
There is a filter splitter slicing filters in two parts, one that can
be encoded down into the datasources,
and one that will run in memory as a post filter. If the datastore
filter capabilities declare support for the
function, it will be encoded and executed in the database, not in
memory, regardless of whether it has
code to be executed in memory.
Each datastore can decide to translate the bits of filters and
functions in a different way, based on what
can or cannot be translated down to native filtering.
Ok but to do that the function must be declared on the datastore driver no ?
e.g if I extend Area to ST_Area, ST_AREA must be declared as Area. I
think for PostGIS about the public static FilterCapabilities
createFilterCapabilities(boolean encodeFunctions) method ?
Did I miss something ?
Cheers
Erwan
Cheers
Andrea
On Fri, Apr 16, 2021 at 4:53 PM Erwan Bocher <erwan.boc...@univ-ubs.fr
<mailto:erwan.boc...@univ-ubs.fr>> wrote:
Hi Andrea,
I'm extending some filter functions to be compliant with SFSSQL.
What about adding this feature in the main geotools module and
declare those new functions in the DB FilterToSQLHelper classes ?
If we have an external module, these functions will not be
optimized in SQL.
Erwan
Le 29/12/2020 à 15:45, Andrea Aime a écrit :
On Wed, Dec 23, 2020 at 3:55 PM Erwan Bocher
<erwan.boc...@univ-ubs.fr <mailto:erwan.boc...@univ-ubs.fr>> wrote:
This is my idea : add support to SFS names in CQL (filter and
expression) without breaking anything in the parser ;-)
As long as they are handled "in memory" I have no objection, just
make sure the semantics is the same as the current functions, if
not, create a separate one.
What alarmed me was the possibility of blindly translating it
down to SQL. That should be done on a database by database basis,
checking what they
support, and under which semantics.
Different semantics between CQL and SQL is an annoying source of
issues. For example, CQL has two valued logic, but SQL has three
valued logic (null gets its own category).
There is a filter translator we created to make sure the SQL
generated behaves in a two-way, which caused several people to
complain about performance (the generated
queries do a number of null checks, and harder to read and optimize)
Cheers
Andrea
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== 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
------------------------------------------------------- /Con
riferimento alla normativa sul trattamento dei dati personali (Reg. UE
2016/679 - Regolamento generale sulla protezione dei dati “GDPR”), si
precisa che ogni circostanza inerente alla presente email (il suo
contenuto, gli eventuali allegati, etc.) è un dato la cui conoscenza è
riservata al/i solo/i destinatario/i indicati dallo scrivente. Se il
messaggio Le è giunto per errore, è tenuta/o a cancellarlo, ogni altra
operazione è illecita. Le sarei comunque grato se potesse darmene
notizia. This email is intended only for the person or entity to which
it is addressed and may contain information that is privileged,
confidential or otherwise protected from disclosure. We remind that -
as provided by European Regulation 2016/679 “GDPR” - copying,
dissemination or use of this e-mail or the information herein by
anyone other than the intended recipient is prohibited. If you have
received this email by mistake, please notify us immediately by
telephone or e-mail./
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Laboratoire Lab-STICC – UMR 6285
Equipe DECIDE
Institut Universitaire de Technologie de Vannes
8, Rue Montaigne - BP 561 56017 Vannes Cedex
T: +33 2 97 62 64 92
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