Query troubleshooting


Query troubleshooting

How can one start troubleshooting a query and subsequently provide a solution in Teradata.

I am looking for best practices.

1. How to identify.
2. What to look for in terms of metrics (system & SQL level)
3. What methods are available and which one to use in which scenario.
4. How to replicate or confirm the problem
5. How to fix and test a solution.
6. Last and but not the least "Best practices for writing SQLs, what to consider from performance prespective in Teradata".

Teradata Employee

Re: Query troubleshooting

The first thing you want to do is to run an explain on the query. This will tell you each step the parsing engine will take when formulating a plan to execute the query. The second step to improve performance would be to collect statistics for any columns in the query that are involved in a join or a filter (where clause). Then run the explain again after collecting statistics and you can see the difference.