COMMENT SQL - Language Statements COMMENT define or change the comment of an object COMMENT COMMENT ON { TABLE object_name | COLUMN table_name.column_name | AGGREGATE agg_name (agg_type) | CAST (sourcetype AS targettype) | CONSTRAINT constraint_name ON table_name | CONVERSION object_name | DATABASE object_name | DOMAIN object_name | FUNCTION func_name (arg1_type, arg2_type, ...) | INDEX object_name | LARGE OBJECT large_object_oid | OPERATOR op (leftoperand_type, rightoperand_type) | OPERATOR CLASS object_name USING index_method | [ PROCEDURAL ] LANGUAGE object_name | RULE rule_name ON table_name | SCHEMA object_name | SEQUENCE object_name | TRIGGER trigger_name ON table_name | TYPE object_name | VIEW object_name } IS 'text' COMMENT stores a comment about a database object. Comments can be easily retrieved with the psql commands \dd, \d+, and \l+. Other user interfaces to retrieve comments can be built atop the same built-in functions that psql uses, namely obj_description and col_description. To modify a comment, issue a new COMMENT command for the same object. Only one comment string is stored for each object. To remove a comment, write NULL in place of the text string. Comments are automatically dropped when the object is dropped. object_name table_name.column_name agg_name constraint_name func_name op rule_name trigger_name The name of the object to be commented. Names of tables, aggregates, domains, functions, indexes, operators, operator classes, sequences, types, and views may be schema-qualified. agg_type The argument data type of the aggregate function, or * if the function accepts any data type. large_object_oid The OID of the large object. PROCEDURAL This is a noise word. sourcetype The name of the source data type of the cast. targettype The name of the target data type of the cast. text The new comment. A comment for a database can only be created in that database, and will only be visible in that database, not in other databases. There is presently no security mechanism for comments: any user connected to a database can see all the comments for objects in that database (although only superusers can change comments for objects that they don't own). Therefore, don't put security-critical information in comments. Attach a comment to the table mytable: COMMENT ON TABLE mytable IS 'This is my table.'; Remove it again: COMMENT ON TABLE mytable IS NULL; Some more examples: COMMENT ON AGGREGATE my_aggregate (double precision) IS 'Computes sample variance'; COMMENT ON CAST (text AS int4) IS 'Allow casts from text to int4'; COMMENT ON COLUMN my_table.my_column IS 'Employee ID number'; COMMENT ON CONVERSION my_conv IS 'Conversion to Unicode'; COMMENT ON DATABASE my_database IS 'Development Database'; COMMENT ON DOMAIN my_domain IS 'Email Address Domain'; COMMENT ON FUNCTION my_function (timestamp) IS 'Returns Roman Numeral'; COMMENT ON INDEX my_index IS 'Enforces uniqueness on employee ID'; COMMENT ON LANGUAGE plpython IS 'Python support for stored procedures'; COMMENT ON LARGE OBJECT 346344 IS 'Planning document'; COMMENT ON OPERATOR ^ (text, text) IS 'Performs intersection of two texts'; COMMENT ON OPERATOR ^ (NONE, text) IS 'This is a prefix operator on text'; COMMENT ON OPERATOR CLASS int4ops USING btree IS '4 byte integer operators for btrees'; COMMENT ON RULE my_rule ON my_table IS 'Logs updates of employee records'; COMMENT ON SCHEMA my_schema IS 'Departmental data'; COMMENT ON SEQUENCE my_sequence IS 'Used to generate primary keys'; COMMENT ON TABLE my_schema.my_table IS 'Employee Information'; COMMENT ON TRIGGER my_trigger ON my_table IS 'Used for RI'; COMMENT ON TYPE complex IS 'Complex number data type'; COMMENT ON VIEW my_view IS 'View of departmental costs'; There is no COMMENT command in the SQL standard.