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Message Posted: Fri, 10 Feb 2006 @ 14:37:12 GMT
Can we create join index on multiple table with UNION stmt ?
One of my reports is accessing big tables (one of table has 1.5 B records) with UNION stmt, but performance is very poor. I would like to create join index on these table by using UNION stmt to increase the performance, is it possible to create join index (?) or give me some ideas to improve the performance of query. And also query is not using any aggregate function. ( I think join index mostly useful for aggregate functions ..)
Sample query is
Select a.col1,a.col2 ... , b.col1,b.col2 .. from table_A a, table_B b Where a.col1=b.col1 ... UNION Select c.col1,c.col2....d.col1,d.col2 .. from table_C c, table_D d Where c.col1=d.col2 .. UNION Select e.col1,e.col2...,f.col1,f.col2... from table_E e, table_F f Where e.col1 = f.col1
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