The catalog pg_am stores information about index
access methods. There is one row for each index access method supported by
the system. The contents of this catalog are discussed in detail in
Chapter 48.
Table 42-3. pg_am Columns
Name
Type
References
Description
amname
name
Name of the access method
amstrategies
int2
Number of operator strategies for this access method
amsupport
int2
Number of support routines for this access method
amorderstrategy
int2
Zero if the index offers no sort order, otherwise the strategy
number of the strategy operator that describes the sort order
amcanunique
bool
Does the access method support unique indexes?
amcanmulticol
bool
Does the access method support multicolumn indexes?
amoptionalkey
bool
Does the access method support a scan without any constraint
for the first index column?
amindexnulls
bool
Does the access method support null index entries?
amconcurrent
bool
Does the access method support concurrent updates?