[schema] Add some Postgres functions

schema/_regroc.postgres.sql

+/* -*- sql -*-
+
+   postgres specific registered procedures,
+   require the plpgsql language installed
+
+add the VALUE function to be able to query the postgres arrays
+in RQL query, example below:
+
+   Any X WHERE X is TimeSerie, X serie S HAVING VALUE(S, 10)>3
+
+*/
+
+CREATE OR REPLACE FUNCTION VALUE(ar1 integer[], indice integer) RETURNS float
+AS $$
+BEGIN
+return ar1[indice];
+END;
+$$ LANGUAGE plpgsql;
\ No newline at end of file

site_cubicweb.py

+
+
+## from cubicweb.schema import CONSTRAINTS
+## from cubes.postgis.schema import params
+## CONSTRAINTS.update((v.__name__, v) for v in params.values())
+
+
+
+from logilab.database import FunctionDescr
+
+from rql.utils import register_function
+
+
+class VALUE(FunctionDescr):
+    minargs = 2
+    maxargs = 2
+    supported_backends = ('postgres',)
+    rtype = 'Float'
+
+
+register_function(VALUE)