Forum Discussion
Optimizing merge operation for large table
Yes, selecting only the columns you need on both queries will usually help. Ensuring that your join columns are both integers will also help. What will help you the most is if both of your ID columns are sorted the same way, then instead of using Table.NestedJoin, you can use Table.Join, and add the final parameter, JoinAlgorithm.SortMerge. I assure you that this will speed up your query significantly. You will need to rename one of the join columns so you don't end up with duplicate column names after the join.
--Nate
Ok I Will try tò select the columns as I wrote above, I'll check performance. But as I read on Chris web blog It shouldn't change much.
I can't use sort merge algorithm as I Need tò join the fact table with many different dim tables. Also I can't use integers because I use text codes to bring in IDs. It's sad that there aren't any other options tò improve performance
Mark the code columns as Key could make any differenze?
