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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="FUNCTIONS-INFO"
>9.19. System Information Functions</A
></H1
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-SESSION-TABLE"
>Table 9-39</A
> shows several
functions that extract session and system information.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-SESSION-TABLE"
></A
><P
><B
>Table 9-39. 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
><CODE
CLASS="FUNCTION"
>current_database()</CODE
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>name of current database</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>current_schema()</CODE
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>name of current schema</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>current_schemas(boolean)</CODE
></TD
><TD
><TT
CLASS="TYPE"
>name[]</TT
></TD
><TD
>names of schemas in search path optionally including implicit schemas</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>current_user</CODE
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>user name of current execution context</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>inet_client_addr()</CODE
></TD
><TD
><TT
CLASS="TYPE"
>inet</TT
></TD
><TD
>address of the remote connection</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>inet_client_port()</CODE
></TD
><TD
><TT
CLASS="TYPE"
>int4</TT
></TD
><TD
>port of the remote connection</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>inet_server_addr()</CODE
></TD
><TD
><TT
CLASS="TYPE"
>inet</TT
></TD
><TD
>address of the local connection</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>inet_server_port()</CODE
></TD
><TD
><TT
CLASS="TYPE"
>int4</TT
></TD
><TD
>port of the local connection</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>session_user</CODE
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>session user name</TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>user</CODE
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>equivalent to <CODE
CLASS="FUNCTION"
>current_user</CODE
></TD
></TR
><TR
><TD
><CODE
CLASS="FUNCTION"
>version()</CODE
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>PostgreSQL version information</TD
></TR
></TBODY
></TABLE
></DIV
><A
NAME="AEN12972"
></A
><A
NAME="AEN12975"
></A
><A
NAME="AEN12978"
></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"
>SET SESSION AUTHORIZATION</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 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
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> <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.
</P
></BLOCKQUOTE
></DIV
><P
> <CODE
CLASS="FUNCTION"
>current_schema</CODE
> returns the name of the schema that is
at the front of 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 search
path returned.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> The search path may 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="AEN13004"
></A
><A
NAME="AEN13006"
></A
><A
NAME="AEN13008"
></A
><A
NAME="AEN13010"
></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="AEN13017"
></A
><P
> <CODE
CLASS="FUNCTION"
>version()</CODE
> returns a string describing the
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> server's version.
</P
><A
NAME="AEN13022"
></A
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-ACCESS-TABLE"
>Table 9-40</A
> lists functions that
allow the user to query object access privileges programmatically.
See <A
HREF="ddl-priv.html"
>Section 5.7</A
> for more information about
privileges.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-ACCESS-TABLE"
></A
><P
><B
>Table 9-40. 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_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_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_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_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
></TBODY
></TABLE
></DIV
><A
NAME="AEN13151"
></A
><A
NAME="AEN13153"
></A
><A
NAME="AEN13155"
></A
><A
NAME="AEN13157"
></A
><A
NAME="AEN13159"
></A
><A
NAME="AEN13161"
></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 ID
(<TT
CLASS="LITERAL"
>pg_user.usesysid</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"
>RULE</TT
>, <TT
CLASS="LITERAL"
>REFERENCES</TT
>, or
<TT
CLASS="LITERAL"
>TRIGGER</TT
>. (Case of the string is not significant, however.)
An example is:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT has_table_privilege('myschema.mytable', 'select');</PRE
><P>
</P
><P
> <CODE
CLASS="FUNCTION"
>has_database_privilege</CODE
> checks whether a user
can access a database in a particular way. The possibilities for its
arguments are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to
<TT
CLASS="LITERAL"
>CREATE</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. The possibilities for its
arguments 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 8.12</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_language_privilege</CODE
> checks whether a user
can access a procedural language in a particular way. The possibilities
for its arguments 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. The possibilities for its
arguments are analogous to <CODE
CLASS="FUNCTION"
>has_table_privilege</CODE
>.
The desired access privilege type must evaluate to
<TT
CLASS="LITERAL"
>CREATE</TT
> or
<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. The possibilities for its
arguments 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
> To test whether a user holds a grant option on the privilege,
append <TT
CLASS="LITERAL"
> WITH GRANT OPTION</TT
> to the privilege key
word; for example <TT
CLASS="LITERAL"
>'UPDATE WITH GRANT OPTION'</TT
>.
</P
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-SCHEMA-TABLE"
>Table 9-41</A
> shows functions that
determine whether a certain object is <I
CLASS="FIRSTTERM"
>visible</I
> in the
current schema search path. 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. For example, 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 9-41. 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_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_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
><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_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
></TBODY
></TABLE
></DIV
><A
NAME="AEN13267"
></A
><A
NAME="AEN13269"
></A
><A
NAME="AEN13271"
></A
><A
NAME="AEN13273"
></A
><A
NAME="AEN13275"
></A
><A
NAME="AEN13277"
></A
><P
> <CODE
CLASS="FUNCTION"
>pg_table_is_visible</CODE
> performs the check for
tables (or views, or any other kind of <TT
CLASS="LITERAL"
>pg_class</TT
> entry).
<CODE
CLASS="FUNCTION"
>pg_type_is_visible</CODE
>,
<CODE
CLASS="FUNCTION"
>pg_function_is_visible</CODE
>,
<CODE
CLASS="FUNCTION"
>pg_operator_is_visible</CODE
>,
<CODE
CLASS="FUNCTION"
>pg_opclass_is_visible</CODE
>, and
<CODE
CLASS="FUNCTION"
>pg_conversion_is_visible</CODE
> perform the same sort of
visibility check for types (and domains), functions, operators, operator classes
and conversions, respectively. 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
>, or <TT
CLASS="TYPE"
>regoperator</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 an unqualified name in
this way — if the name can be recognized at all, it must be visible.
</P
><A
NAME="AEN13294"
></A
><A
NAME="AEN13296"
></A
><A
NAME="AEN13298"
></A
><A
NAME="AEN13300"
></A
><A
NAME="AEN13302"
></A
><A
NAME="AEN13304"
></A
><A
NAME="AEN13306"
></A
><A
NAME="AEN13308"
></A
><A
NAME="AEN13310"
></A
><A
NAME="AEN13312"
></A
><P
> <A
HREF="functions-info.html#FUNCTIONS-INFO-CATALOG-TABLE"
>Table 9-42</A
> lists functions that
extract information from the system catalogs.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-CATALOG-TABLE"
></A
><P
><B
>Table 9-42. 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_viewdef</CODE
>(<TT
CLASS="PARAMETER"
>view_name</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>get <TT
CLASS="COMMAND"
>CREATE VIEW</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 <TT
CLASS="COMMAND"
>CREATE VIEW</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 <TT
CLASS="COMMAND"
>CREATE VIEW</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 <TT
CLASS="COMMAND"
>CREATE VIEW</TT
> command for view</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_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
><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_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_userbyid</CODE
>(<TT
CLASS="PARAMETER"
>userid</TT
>)</TT
></TD
><TD
><TT
CLASS="TYPE"
>name</TT
></TD
><TD
>get user name with given ID</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
><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 set of database OIDs that have objects in the tablespace</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_viewdef</CODE
>,
<CODE
CLASS="FUNCTION"
>pg_get_ruledef</CODE
>,
<CODE
CLASS="FUNCTION"
>pg_get_indexdef</CODE
>,
<CODE
CLASS="FUNCTION"
>pg_get_triggerdef</CODE
>, and
<CODE
CLASS="FUNCTION"
>pg_get_constraintdef</CODE
> respectively
reconstruct the creating command for a view, rule, index, trigger, or
constraint. (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
may be useful when examining the contents of system catalogs.
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_userbyid</CODE
>
extracts a user's name given a user ID number.
<CODE
CLASS="FUNCTION"
>pg_get_serial_sequence</CODE
>
fetches the name of the sequence associated with a serial or
bigserial column. The name is suitably formatted
for passing to the sequence functions (see <A
HREF="functions-sequence.html"
>Section 9.12</A
>).
NULL is returned if the column does not have a sequence attached.
</P
><P
> <CODE
CLASS="FUNCTION"
>pg_tablespace_databases</CODE
> allows usage examination of a
tablespace. It will return a set of OIDs of databases that have objects
stored in the tablespace. If this function returns any row, 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
><A
NAME="AEN13505"
></A
><A
NAME="AEN13507"
></A
><A
NAME="AEN13509"
></A
><P
> The functions shown in <A
HREF="functions-info.html#FUNCTIONS-INFO-COMMENT-TABLE"
>Table 9-43</A
> extract comments
previously stored with the <TT
CLASS="COMMAND"
>COMMENT</TT
> command. A
null value is returned if no comment could be found matching the
specified parameters.
</P
><DIV
CLASS="TABLE"
><A
NAME="FUNCTIONS-INFO-COMMENT-TABLE"
></A
><P
><B
>Table 9-43. 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"
>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"
>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
></TBODY
></TABLE
></DIV
><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 a table with OID 123456.
The one-parameter form of <CODE
CLASS="FUNCTION"
>obj_description</CODE
> requires only
the object OID. It is now deprecated since there is no guarantee that
OIDs are unique across different system catalogs; therefore, the wrong
comment could be returned.
</P
><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
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