From: "John Naylor" <john.naylor@enterprisedb.com>;
Date: Mon, Mar 20, 2023 04:49 PM
To: "Daniel Gustafsson"<daniel@yesql.se>;
Cc: "Pavel Stehule"<pavel.stehule@gmail.com>;"Xiong He"<iihero@qq.com>;"pgsql-bugs"<pgsql-bugs@lists.postgresql.org>;
Subject: Re: About the function current_user
On Mon, Mar 20, 2023 at 3:16 PM Daniel Gustafsson <
daniel@yesql.se> wrote:
> The syntax of current_user and current_role are mandated by the SQL
> specification, we have this note in the documentation:
>
> "current_catalog, current_role, current_schema, current_user,
> session_user, and user have special syntactic status in SQL: they must
> be called without trailing parentheses. In PostgreSQL, parentheses can
> optionally be used with current_schema, but not with the others."
To further illuminate why the last one is special: It's not a fully-reserved keyword:
$ grep current_ src/include/parser/kwlist.h
PG_KEYWORD("current_catalog", CURRENT_CATALOG, RESERVED_KEYWORD, BARE_LABEL)
PG_KEYWORD("current_date", CURRENT_DATE, RESERVED_KEYWORD, BARE_LABEL)
PG_KEYWORD("current_role", CURRENT_ROLE, RESERVED_KEYWORD, BARE_LABEL)
PG_KEYWORD("current_schema", CURRENT_SCHEMA, TYPE_FUNC_NAME_KEYWORD, BARE_LABEL)
PG_KEYWORD("current_time", CURRENT_TIME, RESERVED_KEYWORD, BARE_LABEL)
PG_KEYWORD("current_timestamp", CURRENT_TIMESTAMP, RESERVED_KEYWORD, BARE_LABEL)
PG_KEYWORD("current_user", CURRENT_USER, RESERVED_KEYWORD, BARE_LABEL)
--
John Naylor
EDB:
http://www.enterprisedb.com
