---
name: "comment"
section: "7"
platform: "linux"
package: "postgresql"
version: "7.4.7-6sarge6"
release: "Debian 3.1 (Sarge)"
platforms: ["linux"]
url: "https://new.carta.tech/comment"
---

# comment(7)

define or change the comment of an object

## NAME

COMMENT - define or change the comment of an object

## SYNOPSIS

```
COMMENT ON
{
  TABLE object_name |
  COLUMN table_name.column_name |
  AGGREGATE agg_name (agg_type) |
  CONSTRAINT constraint_name ON table_name |
  DATABASE object_name |
  DOMAIN object_name |
  FUNCTION func_name (arg1_type, arg2_type, ...) |
  INDEX object_name |
  OPERATOR op (leftoperand_type, rightoperand_type) |
  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*

  - *aggname*

  - *constraint\_name*

  - *func\_name*

  - *op*

  - *rule\_name*

  - *trigger\_name*

  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 new comment.

## NOTES

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 COLUMN my_table.my_column 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 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.