Pushdown the whole query

[michal.warecki]

Hi guys,

I have a question regarding pushing down query to source system the whole query without any exceptions. For last few days I was adding a lot of functions, enabling a lot of supports* flags etc. but still there are cases where I've got exceptions what starting to frustrate me. For example this simple query:

SELECT

   tstudent(count(somecolumn) - 1)

FROM sometable

GROUP BY somecolumn;

I've defined tstudent as a pushdown function and when I execute tstudent(count(somecolumn)) it works but in case above there is exception:

org.teiid.api.exception.query.QueryPlannerException: TEIID30258 Expression(s) tstudent((anon_grp0.agg0 - 1)) cannot be pushed to source.

I've debug that and see that all of the scalar functions like -/*+ are not in capabilities functions list. There are only functions that I've added explicitly. Later, I've added -/*+ to addPushDownFunction but it requires prefix to be specified what is not what I want. How can I support such functions?

The best will to be support everything and just push down the whole query.

Best,

Michal

[shawkins]

> I've debug that and see that all of the scalar functions like -/*+ are not in capabilities functions list. There are only functions that I've added explicitly. Later, I've added -/*+ to addPushDownFunction but it requires prefix to be specified what is not what I want. How can I support such functions?

Any function that matches a teiid system function is declared in the getSupportedFunctions list.  There you just declare support by name as it's expected that you'll support all forms of the analogous system function - with the exceptions that specific conversions and formatting can have their pushdown tuned.