sql_features
   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.
  
Table 37.41. sql_features Columns
| Name | Data 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 | YESif the feature is fully supported by the
       current version of PostgreSQL,NOif 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 |