Re: About the function current_user

On Mon, Mar 20, 2023 at 3:16 PM Daniel Gustafsson <daniel(at)yesql(dot)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