Many of these techniques rely on functions and views described in greater detail within the PostgreSQL documentation. In particular, we use a few system administration functions such as pg_relation_size and pg_total_relation_size and system views such as pg_class, pg_index, pg_stat_user_tables, and pg_stat_user_indexes. We also make use of a contributed module named pgstattuple.
We strongly recommend that you get familiar with these functions and views in the PostgreSQL documentation before continuing. After we are finished, we hope to have successfully conveyed just how useful these views are and encourage further exploration. When you are building a highly-available database, there is rarely such a thing as too much information ...
