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.
|Identifier string of the feature|
|Descriptive name of the feature|
|Identifier string of the subfeature, or a zero-length string if not a subfeature|
|Descriptive name of the subfeature, or a zero-length string if not a subfeature|
|Always null, since the PostgreSQL development group does not perform formal testing of feature conformance|
|Possibly a comment about the supported status of the feature|