COMMENT(7)		PostgreSQL 9.2.24 Documentation		    COMMENT(7)



NAME
       COMMENT - define or change the comment of an object

SYNOPSIS
       COMMENT ON
       {
	 AGGREGATE agg_name (agg_type [, ...] ) |
	 CAST (source_type AS target_type) |
	 COLLATION object_name |
	 COLUMN relation_name.column_name |
	 CONSTRAINT constraint_name ON table_name |
	 CONVERSION object_name |
	 DATABASE object_name |
	 DOMAIN object_name |
	 EXTENSION object_name |
	 FOREIGN DATA WRAPPER object_name |
	 FOREIGN TABLE object_name |
	 FUNCTION function_name ( [ [ argmode ] [ argname ] argtype [, ...] ] ) |
	 INDEX object_name |
	 LARGE OBJECT large_object_oid |
	 OPERATOR operator_name (left_type, right_type) |
	 OPERATOR CLASS object_name USING index_method |
	 OPERATOR FAMILY object_name USING index_method |
	 [ PROCEDURAL ] LANGUAGE object_name |
	 ROLE object_name |
	 RULE rule_name ON table_name |
	 SCHEMA object_name |
	 SEQUENCE object_name |
	 SERVER object_name |
	 TABLE object_name |
	 TABLESPACE object_name |
	 TEXT SEARCH CONFIGURATION object_name |
	 TEXT SEARCH DICTIONARY object_name |
	 TEXT SEARCH PARSER object_name |
	 TEXT SEARCH TEMPLATE 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.

       Only one comment string is stored for each object, so to modify a
       comment, issue a new COMMENT command for the same object. To remove a
       comment, write NULL in place of the text string. Comments are
       automatically dropped when their object is dropped.

       For most kinds of object, only the object's owner can set the comment.
       Roles don't have owners, so the rule for COMMENT ON ROLE is that you
       must be superuser to comment on a superuser role, or have the
       CREATEROLE privilege to comment on non-superuser roles. Of course, a
       superuser can comment on anything.

       Comments can be viewed using psql's \d family of commands. Other user
       interfaces to retrieve comments can be built atop the same built-in
       functions that psql uses, namely obj_description, col_description, and
       shobj_description (see Table 9.55, "Comment Information Functions").

PARAMETERS
       object_name, relation_name.column_name, agg_name, constraint_name,
       function_name, operator_name, rule_name, trigger_name
	   The name of the object to be commented. Names of tables,
	   aggregates, collations, conversions, domains, foreign tables,
	   functions, indexes, operators, operator classes, operator families,
	   sequences, text search objects, types, and views can be
	   schema-qualified. When commenting on a column, relation_name must
	   refer to a table, view, composite type, or foreign table.

       agg_type
	   An input data type on which the aggregate function operates. To
	   reference a zero-argument aggregate function, write * in place of
	   the list of input data types.

       source_type
	   The name of the source data type of the cast.

       target_type
	   The name of the target data type of the cast.

       argmode
	   The mode of a function argument: IN, OUT, INOUT, or VARIADIC. If
	   omitted, the default is IN. Note that COMMENT ON FUNCTION does not
	   actually pay any attention to OUT arguments, since only the input
	   arguments are needed to determine the function's identity. So it is
	   sufficient to list the IN, INOUT, and VARIADIC arguments.

       argname
	   The name of a function argument. Note that COMMENT ON FUNCTION does
	   not actually pay any attention to argument names, since only the
	   argument data types are needed to determine the function's
	   identity.

       argtype
	   The data type(s) of the function's arguments (optionally
	   schema-qualified), if any.

       large_object_oid
	   The OID of the large object.

       left_type, right_type
	   The data type(s) of the operator's arguments (optionally
	   schema-qualified). Write NONE for the missing argument of a prefix
	   or postfix operator.

       PROCEDURAL
	   This is a noise word.

       text
	   The new comment, written as a string literal; or NULL to drop the
	   comment.

NOTES
       There is presently no security mechanism for viewing comments: any user
       connected to a database can see all the comments for objects in that
       database. For shared objects such as databases, roles, and tablespaces,
       comments are stored globally so any user connected to any database in
       the cluster can see all the comments for shared objects. 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 COLLATION "fr_CA" IS 'Canadian French';
	   COMMENT ON COLUMN my_table.my_column IS 'Employee ID number';
	   COMMENT ON CONVERSION my_conv IS 'Conversion to UTF8';
	   COMMENT ON CONSTRAINT bar_col_cons ON bar IS 'Constrains column col';
	   COMMENT ON DATABASE my_database IS 'Development Database';
	   COMMENT ON DOMAIN my_domain IS 'Email Address Domain';
	   COMMENT ON EXTENSION hstore IS 'implements the hstore data type';
	   COMMENT ON FOREIGN DATA WRAPPER mywrapper IS 'my foreign data wrapper';
	   COMMENT ON FOREIGN TABLE my_foreign_table IS 'Employee Information in other database';
	   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, integer) IS 'Unary minus';
	   COMMENT ON OPERATOR CLASS int4ops USING btree IS '4 byte integer operators for btrees';
	   COMMENT ON OPERATOR FAMILY integer_ops USING btree IS 'all integer operators for btrees';
	   COMMENT ON ROLE my_role IS 'Administration group for finance tables';
	   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 SERVER myserver IS 'my foreign server';
	   COMMENT ON TABLE my_schema.my_table IS 'Employee Information';
	   COMMENT ON TABLESPACE my_tablespace IS 'Tablespace for indexes';
	   COMMENT ON TEXT SEARCH CONFIGURATION my_config IS 'Special word filtering';
	   COMMENT ON TEXT SEARCH DICTIONARY swedish IS 'Snowball stemmer for Swedish language';
	   COMMENT ON TEXT SEARCH PARSER my_parser IS 'Splits text into words';
	   COMMENT ON TEXT SEARCH TEMPLATE snowball IS 'Snowball stemmer';
	   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';

COMPATIBILITY
       There is no COMMENT command in the SQL standard.



PostgreSQL 9.2.24		  2017-11-06			    COMMENT(7)