53.3. pg_am

The catalog pg_am stores information about relation access methods. There is one row for each access method supported by the system. Currently, only tables and indexes have access methods. The requirements for table and index access methods are discussed in detail in Chapter 63 and Chapter 64 respectively.

Table 53.3. pg_am Columns

Column Type


oid oid

Row identifier

amname name

Name of the access method

amhandler regproc (references pg_proc . oid )

OID of a handler function that is responsible for supplying information about the access method

amtype char

t = table (including materialized views), i = index.


Before PostgreSQL 9.6, pg_am contained many additional columns representing properties of index access methods. That data is now only directly visible at the C code level. However, pg_index_column_has_property() and related functions have been added to allow SQL queries to inspect index access method properties; see Table 9.72 .