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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="FUNCTIONS-INFO"
>9.23. System Information Functions</A
></H1
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-SESSION-TABLE"
>Table 9-47</A
> shows several
functions that extract session and system information.
</P
><P
> In addition to the functions listed in this section, there are a number of
functions related to the statistics system that also provide system
information. See <A
HREF="monitoring-stats.html#MONITORING-STATS-VIEWS"
>Section 26.2.2</A
> for more
information.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-SESSION-TABLE"
></A
><P
><B
>Table 9-47. Session Information Functions</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Return Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>current_catalog</CODE
></TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>name of current database (called <SPAN
CLASS="QUOTE"
>"catalog"</SPAN
> in the SQL standard)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>current_database</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>name of current database</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>current_schema</CODE
>[()]</TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>name of current schema</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>current_schemas</CODE
>(<TT
CLASS="TYPE"
>boolean</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>name[]</TT
></TD
><TD
>names of schemas in search path, optionally including implicit schemas</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>current_user</CODE
></TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>user name of current execution context</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>current_query</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>text of the currently executing query, as submitted
by the client (might contain more than one statement)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_backend_pid</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>int</TT
></TD
><TD
> Process ID of the server process attached to the current session
</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>inet_client_addr</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>inet</TT
></TD
><TD
>address of the remote connection</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>inet_client_port</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>int</TT
></TD
><TD
>port of the remote connection</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>inet_server_addr</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>inet</TT
></TD
><TD
>address of the local connection</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>inet_server_port</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>int</TT
></TD
><TD
>port of the local connection</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_my_temp_schema</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>oid</TT
></TD
><TD
>OID of session's temporary schema, or 0 if none</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_is_other_temp_schema</CODE
>(<TT
CLASS="TYPE"
>oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is schema another session's temporary schema?</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_postmaster_start_time</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>timestamp with time zone</TT
></TD
><TD
>server start time</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_conf_load_time</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>timestamp with time zone</TT
></TD
><TD
>configuration load time</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>session_user</CODE
></TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>session user name</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>user</CODE
></TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>equivalent to <CODE
CLASS="FUNCTION"
>current_user</CODE
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>version</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
><SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> version information</TD
></TR
></TBODY
></TABLE
></DIV
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> <CODE
CLASS="FUNCTION"
>current_catalog</CODE
>, <CODE
CLASS="FUNCTION"
>current_schema</CODE
>,
<CODE
CLASS="FUNCTION"
>current_user</CODE
>, <CODE
CLASS="FUNCTION"
>session_user</CODE
>,
and <CODE
CLASS="FUNCTION"
>user</CODE
> have special syntactic status
in <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
>: they must be called without trailing
parentheses. (In PostgreSQL, parentheses can optionally be used with
<CODE
CLASS="FUNCTION"
>current_schema</CODE
>, but not with the others.)
</P
></BLOCKQUOTE
></DIV
><A
NAME="AEN16928"
></A
><A
NAME="AEN16931"
></A
><A
NAME="AEN16934"
></A
><A
NAME="AEN16937"
></A
><A
NAME="AEN16939"
></A
><A
NAME="AEN16941"
></A
><A
NAME="AEN16943"
></A
><P
> The <CODE
CLASS="FUNCTION"
>session_user</CODE
> is normally the user who initiated
the current database connection; but superusers can change this setting
with <A
HREF="sql-set-session-authorization.html"
><I
>SET SESSION AUTHORIZATION</I
></A
>.
The <CODE
CLASS="FUNCTION"
>current_user</CODE
> is the user identifier
that is applicable for permission checking. Normally it is equal
to the session user, but it can be changed with
<A
HREF="sql-set-role.html"
><I
>SET ROLE</I
></A
>.
It also changes during the execution of
functions with the attribute <TT
CLASS="LITERAL"
>SECURITY DEFINER</TT
>.
In Unix parlance, the session user is the <SPAN
CLASS="QUOTE"
>"real user"</SPAN
> and
the current user is the <SPAN
CLASS="QUOTE"
>"effective user"</SPAN
>.
</P
><P
> <CODE
CLASS="FUNCTION"
>current_schema</CODE
> returns the name of the schema that is
first in the search path (or a null value if the search path is
empty). This is the schema that will be used for any tables or
other named objects that are created without specifying a target schema.
<CODE
CLASS="FUNCTION"
>current_schemas(boolean)</CODE
> returns an array of the names of all
schemas presently in the search path. The Boolean option determines whether or not
implicitly included system schemas such as <TT
CLASS="LITERAL"
>pg_catalog</TT
> are included in the
returned search path.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> The search path can be altered at run time. The command is:
</P><PRE
CLASS="PROGRAMLISTING"
>SET search_path TO <TT
CLASS="REPLACEABLE"
><I
>schema</I
></TT
> [<SPAN
CLASS="OPTIONAL"
>, <TT
CLASS="REPLACEABLE"
><I
>schema</I
></TT
>, ...</SPAN
>]</PRE
><P>
</P
></BLOCKQUOTE
></DIV
><A
NAME="AEN16963"
></A
><A
NAME="AEN16965"
></A
><A
NAME="AEN16967"
></A
><A
NAME="AEN16969"
></A
><P
> <CODE
CLASS="FUNCTION"
>inet_client_addr</CODE
> returns the IP address of the
current client, and <CODE
CLASS="FUNCTION"
>inet_client_port</CODE
> returns the
port number.
<CODE
CLASS="FUNCTION"
>inet_server_addr</CODE
> returns the IP address on which
the server accepted the current connection, and
<CODE
CLASS="FUNCTION"
>inet_server_port</CODE
> returns the port number.
All these functions return NULL if the current connection is via a
Unix-domain socket.
</P
><A
NAME="AEN16976"
></A
><A
NAME="AEN16978"
></A
><P
> <CODE
CLASS="FUNCTION"
>pg_my_temp_schema</CODE
> returns the OID of the current
session's temporary schema, or zero if it has none (because it has not
created any temporary tables).
<CODE
CLASS="FUNCTION"
>pg_is_other_temp_schema</CODE
> returns true if the
given OID is the OID of another session's temporary schema.
(This can be useful, for example, to exclude other sessions' temporary
tables from a catalog display.)
</P
><A
NAME="AEN16983"
></A
><P
> <CODE
CLASS="FUNCTION"
>pg_postmaster_start_time</CODE
> returns the
<TT
CLASS="TYPE"
>timestamp with time zone</TT
> when the
server started.
</P
><A
NAME="AEN16988"
></A
><P
> <CODE
CLASS="FUNCTION"
>pg_conf_load_time</CODE
> returns the
<TT
CLASS="TYPE"
>timestamp with time zone</TT
> when the
server configuration files were last loaded.
(If the current session was alive at the time, this will be the time
when the session itself re-read the configuration files, so the
reading will vary a little in different sessions. Otherwise it is
the time when the postmaster process re-read the configuration files.)
</P
><A
NAME="AEN16993"
></A
><P
> <CODE
CLASS="FUNCTION"
>version</CODE
> returns a string describing the
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> server's version.
</P
><A
NAME="AEN16998"
></A
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-ACCESS-TABLE"
>Table 9-48</A
> lists functions that
allow the user to query object access privileges programmatically.
See <A
HREF="ddl-priv.html"
>Section 5.6</A
> for more information about
privileges.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-ACCESS-TABLE"
></A
><P
><B
>Table 9-48. Access Privilege Inquiry Functions</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Return Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_any_column_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>table</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for any column of table</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_any_column_privilege</CODE
>(<TT
CLASS="PARAMETER"
>table</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for any column of table</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_column_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>table</TT
>,
<TT
CLASS="PARAMETER"
>column</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for column</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_column_privilege</CODE
>(<TT
CLASS="PARAMETER"
>table</TT
>,
<TT
CLASS="PARAMETER"
>column</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for column</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_database_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>database</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for database</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_database_privilege</CODE
>(<TT
CLASS="PARAMETER"
>database</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for database</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_foreign_data_wrapper_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>fdw</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for foreign-data wrapper</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_foreign_data_wrapper_privilege</CODE
>(<TT
CLASS="PARAMETER"
>fdw</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for foreign-data wrapper</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_function_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>function</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for function</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_function_privilege</CODE
>(<TT
CLASS="PARAMETER"
>function</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for function</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_language_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>language</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for language</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_language_privilege</CODE
>(<TT
CLASS="PARAMETER"
>language</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for language</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_schema_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>schema</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for schema</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_schema_privilege</CODE
>(<TT
CLASS="PARAMETER"
>schema</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for schema</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_server_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>server</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for foreign server</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_server_privilege</CODE
>(<TT
CLASS="PARAMETER"
>server</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for foreign server</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>table</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for table</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>(<TT
CLASS="PARAMETER"
>table</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for table</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_tablespace_privilege</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>tablespace</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for tablespace</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>has_tablespace_privilege</CODE
>(<TT
CLASS="PARAMETER"
>tablespace</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for tablespace</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_has_role</CODE
>(<TT
CLASS="PARAMETER"
>user</TT
>,
<TT
CLASS="PARAMETER"
>role</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does user have privilege for role</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_has_role</CODE
>(<TT
CLASS="PARAMETER"
>role</TT
>,
<TT
CLASS="PARAMETER"
>privilege</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>does current user have privilege for role</TD
></TR
></TBODY
></TABLE
></DIV
><A
NAME="AEN17224"
></A
><A
NAME="AEN17226"
></A
><A
NAME="AEN17228"
></A
><A
NAME="AEN17230"
></A
><A
NAME="AEN17232"
></A
><A
NAME="AEN17234"
></A
><A
NAME="AEN17236"
></A
><A
NAME="AEN17238"
></A
><A
NAME="AEN17240"
></A
><A
NAME="AEN17242"
></A
><A
NAME="AEN17244"
></A
><P
> <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
> checks whether a user
can access a table in a particular way. The user can be
specified by name or by OID
(<TT
CLASS="LITERAL"
>pg_authid.oid</TT
>), or if the argument is
omitted
<CODE
CLASS="FUNCTION"
>current_user</CODE
> is assumed. The table can be specified
by name or by OID. (Thus, there are actually six variants of
<CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>, which can be distinguished by
the number and types of their arguments.) When specifying by name,
the name can be schema-qualified if necessary.
The desired access privilege type
is specified by a text string, which must evaluate to one of the
values <TT
CLASS="LITERAL"
>SELECT</TT
>, <TT
CLASS="LITERAL"
>INSERT</TT
>,
<TT
CLASS="LITERAL"
>UPDATE</TT
>, <TT
CLASS="LITERAL"
>DELETE</TT
>, <TT
CLASS="LITERAL"
>TRUNCATE</TT
>,
<TT
CLASS="LITERAL"
>REFERENCES</TT
>, or <TT
CLASS="LITERAL"
>TRIGGER</TT
>. Optionally,
<TT
CLASS="LITERAL"
>WITH GRANT OPTION</TT
> can be added to a privilege type to test
whether the privilege is held with grant option. Also, multiple privilege
types can be listed separated by commas, in which case the result will
be <TT
CLASS="LITERAL"
>true</TT
> if any of the listed privileges is held.
(Case of the privilege string is not significant, and extra whitespace
is allowed between but not within privilege names.)
Some examples:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT has_table_privilege('myschema.mytable', 'select');
SELECT has_table_privilege('joe', 'mytable', 'INSERT, SELECT WITH GRANT OPTION');</PRE
><P>
</P
><P
> <CODE
CLASS="FUNCTION"
>has_any_column_privilege</CODE
> checks whether a user can
access any column of a table in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>,
except that the desired access privilege type must evaluate to some
combination of
<TT
CLASS="LITERAL"
>SELECT</TT
>,
<TT
CLASS="LITERAL"
>INSERT</TT
>,
<TT
CLASS="LITERAL"
>UPDATE</TT
>, or
<TT
CLASS="LITERAL"
>REFERENCES</TT
>. Note that having any of these privileges
at the table level implicitly grants it for each column of the table,
so <CODE
CLASS="FUNCTION"
>has_any_column_privilege</CODE
> will always return
<TT
CLASS="LITERAL"
>true</TT
> if <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
> does for the same
arguments. But <CODE
CLASS="FUNCTION"
>has_any_column_privilege</CODE
> also succeeds if
there is a column-level grant of the privilege for at least one column.
</P
><P
> <CODE
CLASS="FUNCTION"
>has_column_privilege</CODE
> checks whether a user
can access a column in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>,
with the addition that the column can be specified either by name
or attribute number.
The desired access privilege type must evaluate to some combination of
<TT
CLASS="LITERAL"
>SELECT</TT
>,
<TT
CLASS="LITERAL"
>INSERT</TT
>,
<TT
CLASS="LITERAL"
>UPDATE</TT
>, or
<TT
CLASS="LITERAL"
>REFERENCES</TT
>. Note that having any of these privileges
at the table level implicitly grants it for each column of the table.
</P
><P
> <CODE
CLASS="FUNCTION"
>has_database_privilege</CODE
> checks whether a user
can access a database in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to some combination of
<TT
CLASS="LITERAL"
>CREATE</TT
>,
<TT
CLASS="LITERAL"
>CONNECT</TT
>,
<TT
CLASS="LITERAL"
>TEMPORARY</TT
>, or
<TT
CLASS="LITERAL"
>TEMP</TT
> (which is equivalent to
<TT
CLASS="LITERAL"
>TEMPORARY</TT
>).
</P
><P
> <CODE
CLASS="FUNCTION"
>has_function_privilege</CODE
> checks whether a user
can access a function in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
When specifying a function by a text string rather than by OID,
the allowed input is the same as for the <TT
CLASS="TYPE"
>regprocedure</TT
> data type
(see <A
HREF="datatype-oid.html"
>Section 8.16</A
>).
The desired access privilege type must evaluate to
<TT
CLASS="LITERAL"
>EXECUTE</TT
>.
An example is:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT has_function_privilege('joeuser', 'myfunc(int, text)', 'execute');</PRE
><P>
</P
><P
> <CODE
CLASS="FUNCTION"
>has_foreign_data_wrapper_privilege</CODE
> checks whether a user
can access a foreign-data wrapper in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to
<TT
CLASS="LITERAL"
>USAGE</TT
>.
</P
><P
> <CODE
CLASS="FUNCTION"
>has_language_privilege</CODE
> checks whether a user
can access a procedural language in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to
<TT
CLASS="LITERAL"
>USAGE</TT
>.
</P
><P
> <CODE
CLASS="FUNCTION"
>has_schema_privilege</CODE
> checks whether a user
can access a schema in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to some combination of
<TT
CLASS="LITERAL"
>CREATE</TT
> or
<TT
CLASS="LITERAL"
>USAGE</TT
>.
</P
><P
> <CODE
CLASS="FUNCTION"
>has_server_privilege</CODE
> checks whether a user
can access a foreign server in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to
<TT
CLASS="LITERAL"
>USAGE</TT
>.
</P
><P
> <CODE
CLASS="FUNCTION"
>has_tablespace_privilege</CODE
> checks whether a user
can access a tablespace in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to
<TT
CLASS="LITERAL"
>CREATE</TT
>.
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_has_role</CODE
> checks whether a user
can access a role in a particular way.
Its argument possibilities
are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to some combination of
<TT
CLASS="LITERAL"
>MEMBER</TT
> or
<TT
CLASS="LITERAL"
>USAGE</TT
>.
<TT
CLASS="LITERAL"
>MEMBER</TT
> denotes direct or indirect membership in
the role (that is, the right to do <TT
CLASS="COMMAND"
>SET ROLE</TT
>), while
<TT
CLASS="LITERAL"
>USAGE</TT
> denotes whether the privileges of the role
are immediately available without doing <TT
CLASS="COMMAND"
>SET ROLE</TT
>.
</P
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-SCHEMA-TABLE"
>Table 9-49</A
> shows functions that
determine whether a certain object is <I
CLASS="FIRSTTERM"
>visible</I
> in the
current schema search path.
For example, a table is said to be visible if its
containing schema is in the search path and no table of the same
name appears earlier in the search path. This is equivalent to the
statement that the table can be referenced by name without explicit
schema qualification. To list the names of all visible tables:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT relname FROM pg_class WHERE pg_table_is_visible(oid);</PRE
><P>
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-SCHEMA-TABLE"
></A
><P
><B
>Table 9-49. Schema Visibility Inquiry Functions</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Return Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_conversion_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>conversion_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is conversion visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_function_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>function_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is function visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_operator_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>operator_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is operator visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_opclass_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>opclass_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is operator class visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_table_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>table_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is table visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_ts_config_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>config_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is text search configuration visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_ts_dict_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>dict_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is text search dictionary visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_ts_parser_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>parser_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is text search parser visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_ts_template_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>template_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is text search template visible in search path</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_type_is_visible</CODE
>(<TT
CLASS="PARAMETER"
>type_oid</TT
>)</TT
>
</TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is type (or domain) visible in search path</TD
></TR
></TBODY
></TABLE
></DIV
><A
NAME="AEN17417"
></A
><A
NAME="AEN17419"
></A
><A
NAME="AEN17421"
></A
><A
NAME="AEN17423"
></A
><A
NAME="AEN17425"
></A
><A
NAME="AEN17427"
></A
><A
NAME="AEN17429"
></A
><A
NAME="AEN17431"
></A
><A
NAME="AEN17433"
></A
><A
NAME="AEN17435"
></A
><P
> Each function performs the visibility check for one type of database
object. Note that <CODE
CLASS="FUNCTION"
>pg_table_is_visible</CODE
> can also be used
with views, indexes and sequences; <CODE
CLASS="FUNCTION"
>pg_type_is_visible</CODE
>
can also be used with domains. For functions and operators, an object in
the search path is visible if there is no object of the same name
<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>and argument data type(s)</I
></SPAN
> earlier in the path. For operator
classes, both name and associated index access method are considered.
</P
><P
> All these functions require object OIDs to identify the object to be
checked. If you want to test an object by name, it is convenient to use
the OID alias types (<TT
CLASS="TYPE"
>regclass</TT
>, <TT
CLASS="TYPE"
>regtype</TT
>,
<TT
CLASS="TYPE"
>regprocedure</TT
>, <TT
CLASS="TYPE"
>regoperator</TT
>, <TT
CLASS="TYPE"
>regconfig</TT
>,
or <TT
CLASS="TYPE"
>regdictionary</TT
>),
for example:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT pg_type_is_visible('myschema.widget'::regtype);</PRE
><P>
Note that it would not make much sense to test a non-schema-qualified
type name in this way — if the name can be recognized at all, it must be visible.
</P
><A
NAME="AEN17449"
></A
><A
NAME="AEN17451"
></A
><A
NAME="AEN17453"
></A
><A
NAME="AEN17455"
></A
><A
NAME="AEN17457"
></A
><A
NAME="AEN17459"
></A
><A
NAME="AEN17461"
></A
><A
NAME="AEN17463"
></A
><A
NAME="AEN17465"
></A
><A
NAME="AEN17467"
></A
><A
NAME="AEN17469"
></A
><A
NAME="AEN17471"
></A
><A
NAME="AEN17473"
></A
><A
NAME="AEN17475"
></A
><A
NAME="AEN17477"
></A
><A
NAME="AEN17479"
></A
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-CATALOG-TABLE"
>Table 9-50</A
> lists functions that
extract information from the system catalogs.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-CATALOG-TABLE"
></A
><P
><B
>Table 9-50. System Catalog Information Functions</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Return Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>format_type</CODE
>(<TT
CLASS="PARAMETER"
>type_oid</TT
>, <TT
CLASS="PARAMETER"
>typemod</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get SQL name of a data type</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_keywords</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>setof record</TT
></TD
><TD
>get list of SQL keywords and their categories</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_constraintdef</CODE
>(<TT
CLASS="PARAMETER"
>constraint_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get definition of a constraint</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_constraintdef</CODE
>(<TT
CLASS="PARAMETER"
>constraint_oid</TT
>, <TT
CLASS="PARAMETER"
>pretty_bool</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get definition of a constraint</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_expr</CODE
>(<TT
CLASS="PARAMETER"
>expr_text</TT
>, <TT
CLASS="PARAMETER"
>relation_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>decompile internal form of an expression, assuming that any Vars
in it refer to the relation indicated by the second parameter</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_expr</CODE
>(<TT
CLASS="PARAMETER"
>expr_text</TT
>, <TT
CLASS="PARAMETER"
>relation_oid</TT
>, <TT
CLASS="PARAMETER"
>pretty_bool</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>decompile internal form of an expression, assuming that any Vars
in it refer to the relation indicated by the second parameter</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_functiondef</CODE
>(<TT
CLASS="PARAMETER"
>func_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get definition of a function</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_function_arguments</CODE
>(<TT
CLASS="PARAMETER"
>func_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get argument list of function's definition (with default values)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_function_identity_arguments</CODE
>(<TT
CLASS="PARAMETER"
>func_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get argument list to identify a function (without default values)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_function_result</CODE
>(<TT
CLASS="PARAMETER"
>func_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get <TT
CLASS="LITERAL"
>RETURNS</TT
> clause for function</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_indexdef</CODE
>(<TT
CLASS="PARAMETER"
>index_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get <TT
CLASS="COMMAND"
>CREATE INDEX</TT
> command for index</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_indexdef</CODE
>(<TT
CLASS="PARAMETER"
>index_oid</TT
>, <TT
CLASS="PARAMETER"
>column_no</TT
>, <TT
CLASS="PARAMETER"
>pretty_bool</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get <TT
CLASS="COMMAND"
>CREATE INDEX</TT
> command for index,
or definition of just one index column when
<TT
CLASS="PARAMETER"
>column_no</TT
> is not zero</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_ruledef</CODE
>(<TT
CLASS="PARAMETER"
>rule_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get <TT
CLASS="COMMAND"
>CREATE RULE</TT
> command for rule</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_ruledef</CODE
>(<TT
CLASS="PARAMETER"
>rule_oid</TT
>, <TT
CLASS="PARAMETER"
>pretty_bool</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get <TT
CLASS="COMMAND"
>CREATE RULE</TT
> command for rule</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_serial_sequence</CODE
>(<TT
CLASS="PARAMETER"
>table_name</TT
>, <TT
CLASS="PARAMETER"
>column_name</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get name of the sequence that a <TT
CLASS="TYPE"
>serial</TT
> or <TT
CLASS="TYPE"
>bigserial</TT
> column
uses</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>pg_get_triggerdef</CODE
>(<TT
CLASS="PARAMETER"
>trigger_oid</TT
>)</TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get <TT
CLASS="COMMAND"
>CREATE [ CONSTRAINT ] TRIGGER</TT
> command for trigger</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_userbyid</CODE
>(<TT
CLASS="PARAMETER"
>role_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>get role name with given OID</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_viewdef</CODE
>(<TT
CLASS="PARAMETER"
>view_name</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get underlying <TT
CLASS="COMMAND"
>SELECT</TT
> command for view (<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>deprecated</I
></SPAN
>)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_viewdef</CODE
>(<TT
CLASS="PARAMETER"
>view_name</TT
>, <TT
CLASS="PARAMETER"
>pretty_bool</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get underlying <TT
CLASS="COMMAND"
>SELECT</TT
> command for view (<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>deprecated</I
></SPAN
>)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_viewdef</CODE
>(<TT
CLASS="PARAMETER"
>view_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get underlying <TT
CLASS="COMMAND"
>SELECT</TT
> command for view</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_get_viewdef</CODE
>(<TT
CLASS="PARAMETER"
>view_oid</TT
>, <TT
CLASS="PARAMETER"
>pretty_bool</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get underlying <TT
CLASS="COMMAND"
>SELECT</TT
> command for view</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_tablespace_databases</CODE
>(<TT
CLASS="PARAMETER"
>tablespace_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>setof oid</TT
></TD
><TD
>get the set of database OIDs that have objects in the tablespace</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>pg_typeof</CODE
>(<TT
CLASS="PARAMETER"
>any</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>regtype</TT
></TD
><TD
>get the data type of any value</TD
></TR
></TBODY
></TABLE
></DIV
><P
> <CODE
CLASS="FUNCTION"
>format_type</CODE
> returns the SQL name of a data type that
is identified by its type OID and possibly a type modifier. Pass NULL
for the type modifier if no specific modifier is known.
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_get_keywords</CODE
> returns a set of records describing
the SQL keywords recognized by the server. The <TT
CLASS="STRUCTFIELD"
>word</TT
> column
contains the keyword. The <TT
CLASS="STRUCTFIELD"
>catcode</TT
> column contains a
category code: <TT
CLASS="LITERAL"
>U</TT
> for unreserved, <TT
CLASS="LITERAL"
>C</TT
> for column name,
<TT
CLASS="LITERAL"
>T</TT
> for type or function name, or <TT
CLASS="LITERAL"
>R</TT
> for reserved.
The <TT
CLASS="STRUCTFIELD"
>catdesc</TT
> column contains a possibly-localized string
describing the category.
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_get_constraintdef</CODE
>,
<CODE
CLASS="FUNCTION"
>pg_get_indexdef</CODE
>, <CODE
CLASS="FUNCTION"
>pg_get_ruledef</CODE
>,
and <CODE
CLASS="FUNCTION"
>pg_get_triggerdef</CODE
>, respectively reconstruct the
creating command for a constraint, index, rule, or trigger. (Note that this
is a decompiled reconstruction, not the original text of the command.)
<CODE
CLASS="FUNCTION"
>pg_get_expr</CODE
> decompiles the internal form of an
individual expression, such as the default value for a column. It can be
useful when examining the contents of system catalogs. If the expression
might contain Vars, specify the OID of the relation they refer to as the
second parameter; if no Vars are expected, zero is sufficient.
<CODE
CLASS="FUNCTION"
>pg_get_viewdef</CODE
> reconstructs the <TT
CLASS="COMMAND"
>SELECT</TT
>
query that defines a view. Most of these functions come in two variants,
one of which can optionally <SPAN
CLASS="QUOTE"
>"pretty-print"</SPAN
> the result. The
pretty-printed format is more readable, but the default format is more
likely to be interpreted the same way by future versions of
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>; avoid using pretty-printed output for dump
purposes. Passing <TT
CLASS="LITERAL"
>false</TT
> for the pretty-print parameter yields
the same result as the variant that does not have the parameter at all.
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_get_functiondef</CODE
> returns a complete
<TT
CLASS="COMMAND"
>CREATE OR REPLACE FUNCTION</TT
> statement for a function.
<CODE
CLASS="FUNCTION"
>pg_get_function_arguments</CODE
> returns the argument list
of a function, in the form it would need to appear in within
<TT
CLASS="COMMAND"
>CREATE FUNCTION</TT
>.
<CODE
CLASS="FUNCTION"
>pg_get_function_result</CODE
> similarly returns the
appropriate <TT
CLASS="LITERAL"
>RETURNS</TT
> clause for the function.
<CODE
CLASS="FUNCTION"
>pg_get_function_identity_arguments</CODE
> returns the
argument list necessary to identify a function, in the form it
would need to appear in within <TT
CLASS="COMMAND"
>ALTER FUNCTION</TT
>, for
instance. This form omits default values.
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_get_serial_sequence</CODE
> returns the name of the
sequence associated with a column, or NULL if no sequence is associated
with the column. The first input parameter is a table name with
optional schema, and the second parameter is a column name. Because
the first parameter is potentially a schema and table, it is not treated
as a double-quoted identifier, meaning it is lowercased by default,
while the second parameter, being just a column name, is treated as
double-quoted and has its case preserved. The function returns a value
suitably formatted for passing to sequence functions (see <A
HREF="functions-sequence.html"
>Section 9.15</A
>). This association can be modified or
removed with <TT
CLASS="COMMAND"
>ALTER SEQUENCE OWNED BY</TT
>. (The function
probably should have been called
<CODE
CLASS="FUNCTION"
>pg_get_owned_sequence</CODE
>; its current name reflects the fact
that it's typically used with <TT
CLASS="TYPE"
>serial</TT
> or <TT
CLASS="TYPE"
>bigserial</TT
>
columns.)
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_get_userbyid</CODE
> extracts a role's name given
its OID.
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_tablespace_databases</CODE
> allows a tablespace to be
examined. It returns the set of OIDs of databases that have objects stored
in the tablespace. If this function returns any rows, the tablespace is not
empty and cannot be dropped. To display the specific objects populating the
tablespace, you will need to connect to the databases identified by
<CODE
CLASS="FUNCTION"
>pg_tablespace_databases</CODE
> and query their
<TT
CLASS="STRUCTNAME"
>pg_class</TT
> catalogs.
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_typeof</CODE
> returns the OID of the data type of the
value that is passed to it. This can be helpful for troubleshooting or
dynamically constructing SQL queries. The function is declared as
returning <TT
CLASS="TYPE"
>regtype</TT
>, which is an OID alias type (see
<A
HREF="datatype-oid.html"
>Section 8.16</A
>); this means that it is the same as an
OID for comparison purposes but displays as a type name. For example:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT pg_typeof(33);
pg_typeof
-----------
integer
(1 row)
SELECT typlen FROM pg_type WHERE oid = pg_typeof(33);
typlen
--------
4
(1 row)</PRE
><P>
</P
><A
NAME="AEN17749"
></A
><A
NAME="AEN17751"
></A
><A
NAME="AEN17753"
></A
><A
NAME="AEN17755"
></A
><P
> The functions shown in <A
HREF="functions-info.html#FUNCTIONS-INFO-COMMENT-TABLE"
>Table 9-51</A
>
extract comments previously stored with the <A
HREF="sql-comment.html"
><I
>COMMENT</I
></A
> command. A null value is returned if no
comment could be found for the specified parameters.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-COMMENT-TABLE"
></A
><P
><B
>Table 9-51. Comment Information Functions</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Return Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>col_description</CODE
>(<TT
CLASS="PARAMETER"
>table_oid</TT
>, <TT
CLASS="PARAMETER"
>column_number</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get comment for a table column</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>obj_description</CODE
>(<TT
CLASS="PARAMETER"
>object_oid</TT
>, <TT
CLASS="PARAMETER"
>catalog_name</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get comment for a database object</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>obj_description</CODE
>(<TT
CLASS="PARAMETER"
>object_oid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get comment for a database object (<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>deprecated</I
></SPAN
>)</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>shobj_description</CODE
>(<TT
CLASS="PARAMETER"
>object_oid</TT
>, <TT
CLASS="PARAMETER"
>catalog_name</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get comment for a shared database object</TD
></TR
></TBODY
></TABLE
></DIV
><P
> <CODE
CLASS="FUNCTION"
>col_description</CODE
> returns the comment for a table column,
which is specified by the OID of its table and its column number.
<CODE
CLASS="FUNCTION"
>obj_description</CODE
> cannot be used for table columns since
columns do not have OIDs of their own.
</P
><P
> The two-parameter form of <CODE
CLASS="FUNCTION"
>obj_description</CODE
> returns the
comment for a database object specified by its OID and the name of the
containing system catalog. For example,
<TT
CLASS="LITERAL"
>obj_description(123456,'pg_class')</TT
>
would retrieve the comment for the table with OID 123456.
The one-parameter form of <CODE
CLASS="FUNCTION"
>obj_description</CODE
> requires only
the object OID. It is deprecated since there is no guarantee that
OIDs are unique across different system catalogs; therefore, the wrong
comment might be returned.
</P
><P
> <CODE
CLASS="FUNCTION"
>shobj_description</CODE
> is used just like
<CODE
CLASS="FUNCTION"
>obj_description</CODE
> except it is used for retrieving
comments on shared objects. Some system catalogs are global to all
databases within each cluster and their descriptions are stored globally
as well.
</P
><A
NAME="AEN17816"
></A
><A
NAME="AEN17818"
></A
><A
NAME="AEN17820"
></A
><A
NAME="AEN17822"
></A
><A
NAME="AEN17824"
></A
><A
NAME="AEN17826"
></A
><P
> The functions shown in <A
HREF="functions-info.html#FUNCTIONS-TXID-SNAPSHOT"
>Table 9-52</A
>
provide server transaction information in an exportable form. The main
use of these functions is to determine which transactions were committed
between two snapshots.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-TXID-SNAPSHOT"
></A
><P
><B
>Table 9-52. Transaction IDs and snapshots</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Return Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>txid_current</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>get current transaction ID</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>txid_current_snapshot</CODE
>()</TT
></TD
><TD
><TT
CLASS="TYPE"
>txid_snapshot</TT
></TD
><TD
>get current snapshot</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>txid_snapshot_xmin</CODE
>(<TT
CLASS="PARAMETER"
>txid_snapshot</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>get xmin of snapshot</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>txid_snapshot_xmax</CODE
>(<TT
CLASS="PARAMETER"
>txid_snapshot</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>bigint</TT
></TD
><TD
>get xmax of snapshot</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>txid_snapshot_xip</CODE
>(<TT
CLASS="PARAMETER"
>txid_snapshot</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>setof bigint</TT
></TD
><TD
>get in-progress transaction IDs in snapshot</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
><CODE
CLASS="FUNCTION"
>txid_visible_in_snapshot</CODE
>(<TT
CLASS="PARAMETER"
>bigint</TT
>, <TT
CLASS="PARAMETER"
>txid_snapshot</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>boolean</TT
></TD
><TD
>is transaction ID visible in snapshot? (do not use with subtransaction ids)</TD
></TR
></TBODY
></TABLE
></DIV
><P
> The internal transaction ID type (<TT
CLASS="TYPE"
>xid</TT
>) is 32 bits wide and
wraps around every 4 billion transactions. However, these functions
export a 64-bit format that is extended with an <SPAN
CLASS="QUOTE"
>"epoch"</SPAN
> counter
so it will not wrap around during the life of an installation.
The data type used by these functions, <TT
CLASS="TYPE"
>txid_snapshot</TT
>,
stores information about transaction ID
visibility at a particular moment in time. Its components are
described in <A
HREF="functions-info.html#FUNCTIONS-TXID-SNAPSHOT-PARTS"
>Table 9-53</A
>.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-TXID-SNAPSHOT-PARTS"
></A
><P
><B
>Table 9-53. Snapshot components</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="TYPE"
>xmin</TT
></TD
><TD
> Earliest transaction ID (txid) that is still active. All earlier
transactions will either be committed and visible, or rolled
back and dead.
</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>xmax</TT
></TD
><TD
> First as-yet-unassigned txid. All txids greater than or equal to this
are not yet started as of the time of the snapshot, and thus invisible.
</TD
></TR
><TR
><TD
><TT
CLASS="TYPE"
>xip_list</TT
></TD
><TD
> Active txids at the time of the snapshot. The list
includes only those active txids between <TT
CLASS="LITERAL"
>xmin</TT
>
and <TT
CLASS="LITERAL"
>xmax</TT
>; there might be active txids higher
than <TT
CLASS="LITERAL"
>xmax</TT
>. A txid that is <TT
CLASS="LITERAL"
>xmin <= txid <
xmax</TT
> and not in this list was already completed
at the time of the snapshot, and thus either visible or
dead according to its commit status. The list does not
include txids of subtransactions.
</TD
></TR
></TBODY
></TABLE
></DIV
><P
> <TT
CLASS="TYPE"
>txid_snapshot</TT
>'s textual representation is
<TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>xmin</I
></TT
>:<TT
CLASS="REPLACEABLE"
><I
>xmax</I
></TT
>:<TT
CLASS="REPLACEABLE"
><I
>xip_list</I
></TT
></TT
>.
For example <TT
CLASS="LITERAL"
>10:20:10,14,15</TT
> means
<TT
CLASS="LITERAL"
>xmin=10, xmax=20, xip_list=10, 14, 15</TT
>.
</P
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