The table sql_features contains information about which formal features defined in the SQL standard are supported by PostgreSQL. This is the same information that is presented in Appendix D. There you can also find some additional background information.
sql_features ColumnsColumn Type
Description
feature_id character_data
Identifier string of the feature
feature_name character_data
Descriptive name of the feature
sub_feature_id character_data
Identifier string of the subfeature, or a zero-length string if not a subfeature
sub_feature_name character_data
Descriptive name of the subfeature, or a zero-length string if not a subfeature
is_supported yes_or_no
YES if the feature is fully supported by the current version of PostgreSQL, NO if not
is_verified_by character_data
Always null, since the PostgreSQL development group does not perform formal testing of feature conformance
comments character_data
Possibly a comment about the supported status of the feature