The name of the object to be be commented. Names of tables,
aggregates, domains, functions, indexes, operators, sequences, types,
and views
may be schema-qualified.
text
The comment to add.
Outputs
COMMENT
Message returned if the table is successfully commented.
Description
COMMENT stores a comment about a database object.
Comments can be
easily retrieved with psql's
\dd, \d+, or \l+
commands. 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.
Note: 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.
Usage
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 COLUMN my_table.my_field IS 'Employee ID number';
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 OPERATOR ^ (text, text) IS 'Performs intersection of two texts';
COMMENT ON OPERATOR ^ (NONE, text) IS 'This is a prefix operator on text';
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 R.I.';
COMMENT ON TYPE complex IS 'Complex Number datatype';
COMMENT ON VIEW my_view IS 'View of departmental costs';
