Postgresql 中文操作指南

COMMENT

COMMENT——定义或更改对象的注释

COMMENT — define or change the comment of an object

Synopsis

COMMENT ON
{
  ACCESS METHOD object_name |
  AGGREGATE aggregate_name ( aggregate_signature ) |
  CAST (source_type AS target_type) |
  COLLATION object_name |
  COLUMN relation_name.column_name |
  CONSTRAINT constraint_name ON table_name |
  CONSTRAINT constraint_name ON DOMAIN domain_name |
  CONVERSION object_name |
  DATABASE object_name |
  DOMAIN object_name |
  EXTENSION object_name |
  EVENT TRIGGER 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 |
  MATERIALIZED VIEW object_name |
  OPERATOR operator_name (left_type, right_type) |
  OPERATOR CLASS object_name USING index_method |
  OPERATOR FAMILY object_name USING index_method |
  POLICY policy_name ON table_name |
  [ PROCEDURAL ] LANGUAGE object_name |
  PROCEDURE procedure_name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ] |
  PUBLICATION object_name |
  ROLE object_name |
  ROUTINE routine_name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ] |
  RULE rule_name ON table_name |
  SCHEMA object_name |
  SEQUENCE object_name |
  SERVER object_name |
  STATISTICS object_name |
  SUBSCRIPTION 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 |
  TRANSFORM FOR type_name LANGUAGE lang_name |
  TRIGGER trigger_name ON table_name |
  TYPE object_name |
  VIEW object_name
} IS { string_literal | NULL }

where aggregate_signature is:

* |
[ argmode ] [ argname ] argtype [ , ... ] |
[ [ argmode ] [ argname ] argtype [ , ... ] ] ORDER BY [ argmode ] [ argname ] argtype [ , ... ]

Description

COMMENT 存储有关数据库对象的注释。

COMMENT stores a comment about a database object.

每个对象仅存储一个注释字符串，因此要修改注释，请对同一对象发出新的 COMMENT 命令。要移除注释，请在文本字符串中写 NULL 。当对象被删除时，注释将被自动删除。

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.

在要进行注释的对象上获取一个 SHARE UPDATE EXCLUSIVE 锁。

A SHARE UPDATE EXCLUSIVE lock is acquired on the object to be commented.

对于大多数类型的对象，只有对象的拥有者可以设置注释。角色没有所有者，因此 COMMENT ON ROLE 的规则是：必须成为超级用户才能对超级用户角色进行注释，或者具有 CREATEROLE 权限并且被授予目标角色上的 ADMIN OPTION 。同样，访问方法也没有所有者；必须成为超级用户才能对访问方法进行注释。当然，超级用户可以对任何事物进行注释。

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 and have been granted ADMIN OPTION on the target role. Likewise, access methods don’t have owners either; you must be superuser to comment on an access method. Of course, a superuser can comment on anything.

可以使用 psql 的 \d 命令族查看注释。其他用于检索注释的用户界面可以构建在 psql 所使用的相同内置函数之上，即 obj_description 、 col_description 和 shobj_description （见 Table 9.78 ）。

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 9.78).

Parameters

  • object_namerelation_name.column_nameaggregate_nameconstraint_namefunction_nameoperator_namepolicy_nameprocedure_nameroutine_namerule_nametrigger_name

    • The name of the object to be commented. Names of objects that reside in schemas (tables, functions, etc.) can be schema-qualified. When commenting on a column, relation_name must refer to a table, view, composite type, or foreign table.

  • table_name__domain_name

    • When creating a comment on a constraint, a trigger, a rule or a policy these parameters specify the name of the table or domain on which that object is defined.

  • 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, procedure, or aggregate argument: IN, OUT, INOUT, or VARIADIC. If omitted, the default is IN. Note that COMMENT 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, procedure, or aggregate argument. Note that COMMENT 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 of a function, procedure, or aggregate argument.

  • 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 operator.

  • PROCEDURAL

    • This is a noise word.

  • type_name

    • The name of the data type of the transform.

  • lang_name

    • The name of the language of the transform.

  • string_literal

    • The new comment contents, written as a string literal.

  • NULL

    • Write NULL to drop the comment.

Notes

目前没有用于查看注释的安全机制：连接到数据库的任何用户都可以查看该数据库中所有对象的注释。对于诸如数据库、角色和表空间等共享对象，注释会全局存储，因此连接到集群中任何数据库的任何用户都可以查看所有共享对象的注释。因此，请不要在注释中放入安全关键信息。

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

附加一个注释到表 mytable ：

Attach a comment to the table mytable:

COMMENT ON TABLE mytable IS 'This is my table.';

再次将其移除：

Remove it again:

COMMENT ON TABLE mytable IS NULL;

更多一些示例：

Some more examples:

COMMENT ON ACCESS METHOD gin IS 'GIN index access method';
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 CONSTRAINT dom_col_constr ON DOMAIN dom IS 'Constrains col of domain';
COMMENT ON DATABASE my_database IS 'Development Database';
COMMENT ON DOMAIN my_domain IS 'Email Address Domain';
COMMENT ON EVENT TRIGGER abort_ddl IS 'Aborts all DDL commands';
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 MATERIALIZED VIEW my_matview IS 'Summary of order history';
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 POLICY my_policy ON mytable IS 'Filter rows by users';
COMMENT ON PROCEDURE my_proc (integer, integer) IS 'Runs a report';
COMMENT ON PUBLICATION alltables IS 'Publishes all operations on all tables';
COMMENT ON ROLE my_role IS 'Administration group for finance tables';
COMMENT ON ROUTINE my_routine (integer, integer) IS 'Runs a routine (which is a function or procedure)';
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 STATISTICS my_statistics IS 'Improves planner row estimations';
COMMENT ON SUBSCRIPTION alltables IS 'Subscription for all operations on all tables';
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 TRANSFORM FOR hstore LANGUAGE plpython3u IS 'Transform between hstore and Python dict';
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

SQL 标准中没有 COMMENT 命令。

There is no COMMENT command in the SQL standard.