We all know what a relational database and SQL language are and how to get or modify data in a database. The algorithm is straightforward:
1) Write an SQL query
2) Send it to the database
3) Get the result
It's all straightforward, but only until the moment when we get the result is not what we expected, or do not get it at all, or gave up to wait for the data, etc. It happens because, between the second and third steps, many things affect the result. When we face the issue related to query execution, it can be challenging to solve the problem without knowing what is happening inside. And in this session, we will go with you the same way that the query in SQL Server and Postgres goes from the moment you run it to the moment of receiving the result. Following this path will help us understand why we get such a result under certain conditions and work more efficiently with databases.