COMMENTNameCOMMENT -- define or change the comment of an object SynopsisCOMMENT 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'Description 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.
Parameters- 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.
Notes 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.
Examples 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';
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