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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