I wrote about query store hints before when they were first released in Azure SQL databases. However, there are some tricks related to managing query store hints we will explore on this blog post. Applying Query Store Hint When we apply a query store hint, the query already exists in query store, and it has … Read more
In the first article of this series, we learned what query parsing is and what impact it has on query performance. In this part of the series, we shall continue the discussion and look at Soft Parsing of the query. Query Processing Workflow Revisited As we saw in the previous installment, a query has to undergo Hard Parsing at least… Read more
Introduction When it comes to tuning a badly-performing query, there are many things that need to be checked. There may be poor query design causing the query to run slowly. There could be an issue with the underlying hardware such as CPU or IO which is bringing the performance of the query down. There could be stale statistics or missing… Read more
In the first three installments of this series I outlined the mechanisms used by Oracle to analyze a very simple query. Sticking with the informal approach, I’m going to look at the high-level strategy the optimizer takes when handling a more complex query. To do this I’ll be looking at query blocks, scratching the surface of query transformation, explaining why it’s a… Read more
