GV$FILE_OPTIMIZED_HISTOGRAM definition in Oracle Database 11.2
GV$FILE_OPTIMIZED_HISTOGRAM
select
k.inst_id, -- INST_ID NUMBER
k.kcfiofno, -- FILE# NUMBER
k.kcfiomaxdur, -- SINGLEBLKRDTIM_MICRO NUMBER
k.kcfioval -- SINGLEBLKRDS NUMBER
from
x$kcfiofchist k,
x$kccfe f
where
f.fedup <> 0 and f.fenum=k.kcfiofno