SELECT
    /*@o*/XMLCAST(XMLQUERY('declare namespace xdms="smth"; $p//xdms:communication/xdms:document/xdms:num/xdms:number' PASSING mh.xml AS "p" RETURNING CONTENT) AS VARCHAR2(255)) num
    /*@p*/
    CONVERT((XPATH('//xdms:communication/xdms:document/xdms:num/xdms:number', mh.xml, ARRAY[['xdms', 'smth']]))[1]::text::bytea, 'UTF8', 'WIN1251') AS num
    /**/
from medo_history mh
WHERE document_id = :id
  AND event_id = 1
  AND is_out = 0