Comments

COMMENT ON

The COMMENT ON statement associates comments to databases, tables, or columns.

Privileges

The user must be a member of the admin role or have the CREATE privilege on the object they are commenting on. By default, the root user belongs to the admin role.

Syntax

COMMENT ON [DATABASE <database_name> | TABLE <table_name> | COLUMN <column_name> ] IS <comment_text>;

Parameters

Parameter	Description
`database_name`	The name of the database to comment on.
`table_name`	The name of the table to comment on.
`column_name`	The name of the column to comment on.
`comment_text`	The comment to be associated to the object.

Examples

Add a comment to a database.

-- 1. Add a comment to the ts_db database.

COMMENT ON DATABASE ts_db IS 'database for power statistics';
COMMENT ON DATABASE

-- 2. Check the database's comments.

SHOW DATABASES WITH COMMENT;
  database_name | engine_type |            comment
----------------+-------------+--------------------------------
  db1           | RELATIONAL  | NULL
  db2           | RELATIONAL  | NULL
  ts_db         | RELATIONAL  | database for power statistics
...
(6 rows)

Add a comment to a table.

-- 1. Add a comment to the power table.

COMMENT ON TABLE power IS 'power for all devices';
COMMENT ON TABLE

-- 2. Check the table's comments.

SHOW TABLES WITH COMMENT;
  table_name  |    table_type     |      comment
--------------+-------------------+--------------------
  power       | TIME SERIES TABLE | power for all devices
(1 row)

Add a comment to a column.

-- 1. Add a comment to the ts column of the power table.

COMMENT ON COLUMN power.ts IS 'auto-generated';
COMMENT ON COLUMN

-- 2. Check the column's comments.

SHOW COLUMNS FROM power WITH COMMENT;
  column_name |  data_type  | is_nullable | column_default | generation_expression |  indices  | is_hidden | is_tag |              comment
--------------+-------------+-------------+----------------+-----------------------+-----------+-----------+--------+-------------------------------------
  ts          | TIMESTAMPTZ |    false    | NULL           |                       | {primary} |   false   | false  | auto-generated
  col         | INT4        |    true     | NULL           |                       | {}        |   false   | false  | NULL
  tag1        | INT4        |    false    | NULL           |                       | {}        |   false   |  true  | primary tag for comment
  tag2        | INT4        |    true     | NULL           |                       | {}        |   false   |  true  | tag for comment
(4 rows)

# Comments

# COMMENT ON

# Privileges

# Syntax

# Parameters

# Examples