(2012/03/15 0:29), Tom Lane wrote:
> The posted patch for file_fdw takes the
> approach of silently filtering out rows for which they're not true,
> which is not obviously the right thing either --- quite aside from
> whether that's a sane semantics, it's not going to scale to foreign key
> constraints, and even for simple NOT NULL and CHECK constraints it
> results in a runtime penalty on selects, which is not what people would
> expect from a constraint.
I investigated DB2 a little bit. In DB2, the user can specify the
VALIDATE_DATA_FILE option as a generic option for an external table
attached to a data file, which specifies if the wrapper verifies that
the data file is sorted. How about introducing this kind of option to
file_fdw? It might be better that the default value for the option is
'false', and if the value is set to 'true', then file_fdw verifies NOT
NULL, CHECK, and foreign key constraints.
Best regards,
Etsuro Fujita