Parallel query execution with SPI

Hi hackers,

It is possible to execute query concurrently using SPI?
If so, how it can be enforced?
I tried to open cursor with CURSOR_OPT_PARALLEL_OK flag but it doesn't 
help: query is executed by single backend while the same query been 
launched at top level uses parallel plan:
    fsstate->portal = SPI_cursor_open_with_args(NULL, fsstate->query, 
fsstate->numParams, argtypes, values, nulls, true, CURSOR_OPT_PARALLEL_OK);    ...    SPI_cursor_fetch(fsstate->portal,
true,1);
 

Thanks in advance,

-- 
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company