PostgreSQL provides very rich features for creating and managing indexes, both single column-based or multi-column-based, as well as multiple types of indexes that can be built.
Thanks to the EXPLAIN command, a database administrator can inspect a slow query and see how the optimizer has thought about what the best access to the underlying data is, and thanks to an understanding of how PostgreSQL works, the administrator can decide which indexes to create in order to tune the performances.
PostgreSQL also provides a rich set of statistics that is used to both extract the quality and the quantity of data within every table, therefore being able to generate an execution plan, and to monitor which indexes are used and when. Auto-explain is another useful module that can be used to silently monitor slow queries and execution plans and see how the cluster is performing without any need to manually execute every suspect statement.
It is important to emphasize that performance tuning...
