Got the issue: There are two redundant and inconsistent queries, one in parameters.xql and one in parameters-postgresql.xql. The variant in parameters-postgresql.xql does NOT contain datatype in the select statement.
Cheers! Frank
in acs-subsite/www/shared/ in oacs-5-9 (or in the released tar file) there is no parameters-postgresql.xql (see [1]).
-g
[1] https://github.com/openacs/openacs-core/tree/oacs-5-9/packages/acs-subsite/www/shared