Re: IO Bottleneck won't go away

I've found that when doing multiple outer joins, performance is often poor. If possible, breaking up the query into separate steps vastly improves performance. It's real easy to start down the "it can all be done in one statement" path and keep going. I had one query that was taking 12 _hours_ to run with multiple outer joins. When I split it up, it reduced the time to 6 _minutes_!

>>I'm currently experiencing a very annoting IO Bottle neck.

While running a "create as select" I experience massive IO bottleneck. This is unsurprising given the size of the Tables I am Joining (1 mill rows * 4 tables) three tables are outerjoined to the same main table.

In order to speed this up I took the recommended action of creating Indexes on the tables to be outer joined. However the index creation takes an age due to the amount of IO they cause. I've tried creating these in parallel to see if that helped, but the IO Bottleneck means that the overall performance is virtually unaffeted.

All I am currently able to do is move the bottleneck around and so gain no perfomence improvement.

any ideas??

This query is running on Oracle 734

<< Received on Fri Oct 29 1999 - 08:34:37 CDT