Query tuning is a multi-step process that generally goes something like this:
1. Establish a baseline. Generate the execution plan and establish the current performance characteristics of the existing query. This gives you a base for comparison when you perform tuning experiments.
2. Analyze the current execution plan. You should understand the path to the data that is being taken by NonStop SQL.
3. Identify problems with the existing plan, and come up with a better plan.
4. Make changes to get the plan you want. This is not always obvious. You may have to perform multiple tuning experiments to arrive at the solution.
5. Having implemented the changes, generate a new execution plan, and re-measure the performance.
6. Compare the results with the baseline. If things have improved, incorporate the change into the new baseline, otherwise abandon the change.
Repeat steps 2 through 6 until you are satisfied with the query performance.
1. Establish a baseline. Generate the execution plan and establish the current performance characteristics of the existing query. This gives you a base for comparison when you perform tuning experiments.
2. Analyze the current execution plan. You should understand the path to the data that is being taken by NonStop SQL.
3. Identify problems with the existing plan, and come up with a better plan.
4. Make changes to get the plan you want. This is not always obvious. You may have to perform multiple tuning experiments to arrive at the solution.
5. Having implemented the changes, generate a new execution plan, and re-measure the performance.
6. Compare the results with the baseline. If things have improved, incorporate the change into the new baseline, otherwise abandon the change.
Repeat steps 2 through 6 until you are satisfied with the query performance.
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