There are some common mistakes and bad practices that developers may fall into. For example, a relational database is based on set theory; new developers tend to think in the scope of row-level manipulation instead of set manipulation. In addition, a lot of people create poor physical designs because they aren't familiar with relational-database modeling. In this section, we'll cover common mistakes in writing queries. For modelling issues, it's recommended to have a look at normalization because normalization also can boost performance by reducing data size and enhance statistics. In general, there are several issues that might lead to bad performance:
- Incorrect statistics: This might happen if there are cross-correlations among predicates, or if the predicates have an immutable function.
- Unnecessary data retrieval: When there...