Hello,
We would like to map a foreign table created with PostGreSQL 9.3. This foreign table is associated with a foreign data wrapper connected to google search web service. The idea is to create a SPARQL End Point with a multitude of web services with the ability to catch data on the fly (no intermediate storage) The table is created as follow, the full documentation is here : https://github.com/cyga/www_fdw/wiki/Examples CREATE FOREIGN TABLE www_fdw_google_search ( /* parameters used in request */ q text, /* fields in response */ GsearchResultClass text, unescapedUrl text, url text, visibleUrl text, cacheUrl text, title text, titleNoFormatting text, content text ) SERVER www_fdw_server_google_search; We experience some issues due to the SQL query generated by D2RQ : * ?The data wrapper allows only one parameter in the WHERE clause (q field as input) but D2RQ adds IS NOT NULL condition for every fields used in the SPARQL query * We have tried with D2RQ 0.8.1 and did not manage to remove these extra conditions * We have tried with 0.7 version and it works, the WHERE clause is built with only the requested parameters Question #1 : Is there a possibility to remove the IS NOT NULL conditions in 0.8.1 version ? * ?The data wrapper is not very tolerant with SQL language and it does not support the multiple table renaming * When we use 3 parameters in a SPARQL query mapped in the same foreign table, the SQL query generated by D2RQ creates T1_table, T2_table and T3_table as aliases of the the same table. This works with a local table in PostGreSQL but not with the www_fdw foreign table. Question #2 : Is there a possibility to disable the table renaming ? We do not understand why it is necessary to create these extra tables because the mapping is done on a unique table in PostGreSQL. Question #3 : Have you ever tried this kind of configuration between D2RQ and PostGreSQL Foreign Table ? Many thanks Thomas C.
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