pg_am

The pg_am table stores information about index access methods. There is one row for each index access method supported by the system.

Table 1. pg_catalog.pg_am

column	type	references	description
amname	name		Name of the access method
amstrategies	smallint		Number of operator strategies for this access method
amsupport	smallint		Number of support routines for this access method
amorderstrategy	smallint		Zero if the index offers no sort order, otherwise the strategy number of the strategy operator that describes the sort order
amcanunique	boolean		Does the access method support unique indexes?
amcanmulticol	boolean		Does the access method support multicolumn indexes?
amoptionalkey	boolean		Does the access method support a scan without any constraint for the first index column?
amindexnulls	boolean		Does the access method support null index entries?
amstorage	boolean		Can index storage data type differ from column data type?
amclusterable	boolean		Can an index of this type be clustered on?
amcanshrink	boolean		Can an index of this type be shrinked?
aminsert	regproc	pg_proc.oid	“Insert this tuple” function
ambeginscan	regproc	pg_proc.oid	“Start new scan” function
amgettuple	regproc	pg_proc.oid	“Next valid tuple” function
amgetmulti	regproc	pg_proc.oid	“Fetch multiple tuples” function
amrescan	regproc	pg_proc.oid	“Restart this scan” function
amendscan	regproc	pg_proc.oid	“End this scan” function
ammarkpos	regproc	pg_proc.oid	“Mark current scan position” function
amrestrpos	regproc	pg_proc.oid	“Restore marked scan position” function
ambuild	regproc	pg_proc.oid	“Build new index” function
ambulkdelete	regproc	pg_proc.oid	Bulk-delete function
amvacuumcleanup	regproc	pg_proc.oid	Post-VACUUM cleanup function
amcostestimate	regproc	pg_proc.oid	Function to estimate cost of an index scan
amoptions	regproc	pg_proc.oid	Function to parse and validate reloptions for an index