Today I tried out the 25-BuildVersion of sapdb, hopening for a performance increase. But there is still a Query, which takes more than 10 minutes ( after that time I killed the process).
So I seperated the subqueries from that Query, and found out, that they are the main reason for the performance lag. They take about 20 seconds while first executing. Strange: they only take 2-3 seconds, while executing them a second or a thirt time.. (maybe, there is saved some DATA in a Cache ? )
But I guess, the main problem are the ca. 20 seconds, they need the first time. So the hole query has 3 Subqueries. The main Query without the subqueries takes only some seconds, and so should it be.
The Subqueries have the following form :
(
Select 1 from SYSDBA.DUAL where exists (
select a.column from view a, view b, view c where condition1 and condition2 and condition3 and condition4 and condition5 and not exist (
select d.column from view d, view e, view f where condition1 and condition2 and condition3 and condition4 and condition5)
)
You see, there are also Subqueries in Subqueries.
The EXPLAIN Statement tells me, that there is only one Tablescan on the DUAL Table, else only used Indices.
The Statistics is also up to date...
Best regards, Danny
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