Oracle performance issue with "UNION ALL" in 10g

[victoryhendry]

Hi,

just assume that

SQL Query :

SQL1 UNION ALL SQL2

separately exection times are

SQL1 -- 5 seconds (total count - 5,00000)

SQL2 -- 10 seconds (total count - 4,00000)

if I use UNION ALL. it takes 30 minutes to complete the execution.why it takes that much time if I use UNION ALL.?

Thanks

[victoryhendry]

could you pls look on it

[davey23uk]

look at what, you haven;t posted anything to look at

[victoryhendry]

is therey anyway to improve performance of that query ? if we use UNION ALL it takes much time. do we need to use any hints or any other function?

[davey23uk]

what query, you havent posted anything
no query
no execution plan
no anything

posting stuff in different colours doesnt make it less true

[PAVB]

Hi,

just assume that

SQL Query :

SQL1 UNION ALL SQL2

separately exection times are

SQL1 -- 5 seconds (total count - 5,00000)

SQL2 -- 10 seconds (total count - 4,00000)

if I use UNION ALL. it takes 30 minutes to complete the execution.why it takes that much time if I use UNION ALL.?

Thanks

Trace the three executions, compare execution plans as well as buffer_gets.