The pgstattuple contributed extension is also useful for analysis, but it produces a deep scan of single objects identified through other means. It's best to use the extension to get storage-related data regarding indexes or tables matched with the preceding queries. To use it, it must first be installed by a superuser account. It can also only be utilized by a superuser account.
To install the extension, execute this SQL query:
CREATE EXTENSION pgstattuple;
To use it, select from it as if it were a normal table or view. The only difference is that we use it as a function with the name of the table we want to analyze. For example, to obtain storage statistics on the pg_class table, we could execute this:
SELECT * FROM ...
