Below HANA Query is not sorting the Partition's members based on date and time in descending order.
"select mandt, kappl,
objky,
kschl,
spras,
parnr,
parvw,
erdat,
eruhr,
nacha,
aende,
vstat,
row_number( ) OVER ( PARTITION BY mandt,kappl,objky,kschl,spras,parnr,parvw ORDER BY erdat, eruhr desc ) as row_num
FROM nast
WHERE mandt = SESSION_CONTEXT( 'CLIENT' );"