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$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.84 2001/11/2105:53:41 thomas Exp $

$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.85 2001/11/2122:33:14 tgl Exp $

PostgreSQL documentation

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<tbody>

<row>

<entry>current_user</>

<entry>name</>

<entry><function>current_user</></entry>

<entry><type>name</></entry>

<entry>user name of current execution context</>

</row>

<row>

<entry>session_user</>

<entry>name</>

<entry><function>session_user</></entry>

<entry><type>name</></entry>

<entry>session user name</>

</row>

<row>

<entry>user</>

<entry>name</>

<entry><function>user</></entry>

<entry><type>name</></entry>

<entry>equivalent to <function>current_user</></>

</row>

</tbody>

<para>

The <function>session_user</> is the user that initiated a database

connection and is fixed for the duration of that connection. The

connection; it is fixed for the duration of that connection. The

<function>current_user</> is the user identifier that is applicable

for permission checking. Currently it is always equal to the session

user, but in the future there might be <quote>setuid</> functions and

</para>

<para>

Note that these functions have special syntactic status in <acronym>SQL</>;

Note that these functions have special syntactic status in <acronym>SQL</>:

they must be called without trailing parentheses.

</para>

</para>

</note>

<table>

<title>System Information Functions</>

<tgroup cols="3">

<thead>

<row><entry>Name</> <entry>Return Type</> <entry>Description</></row>

</thead>

<tbody>

<row>

<entry><function>version</></entry>

<entry><type>text</></entry>

<entry>PostgreSQL version information</>

</row>

</tbody>

</tgroup>

</table>

<indexterm zone="functions-misc">

<primary>version</primary>

</indexterm>

<para>

<function>version()</> returns a string describing the PostgreSQL

server's version.

</para>

<table>

<title>Access Privilege Inquiry Functions</>

<tgroup cols="3">

<para>

<function>has_table_privilege</> determines whether a user

can access a table in a particular way. The user can be

specified by name or by ID (<classname>pg_user</>.<structfield>usesysid</>) or if the argument is omitted

specified by name or by ID

(<classname>pg_user</>.<structfield>usesysid</>), or if the argument is

omitted

<function>current_user</> is assumed. The table can be specified

by name or by OID. (Thus, there are actually six variants of

<function>has_table_privilege</>, which can be distinguished by

</para>

<table>

<title>System Information Functions</>

<title>Catalog Information Functions</>

<tgroup cols="3">

<thead>

<row><entry>Name</> <entry>Return Type</> <entry>Description</></row>

</thead>

<tbody>

<row>

<entry>version</>

<entry>text</>

<entry>PostgreSQL version information</>

<entry><function>pg_get_viewdef</>(<parameter>viewname</parameter>)</entry>

<entry><type>text</></entry>

<entry>Get CREATE VIEW command for view</>

</row>

<row>

<entry><function>pg_get_ruledef</>(<parameter>rulename</parameter>)</entry>

<entry><type>text</></entry>

<entry>Get CREATE RULE command for rule</>

</row>

<row>

<entry><function>pg_get_indexdef</>(<parameter>indexOID</parameter>)</entry>

<entry><type>text</></entry>

<entry>Get CREATE INDEX command for index</>

</row>

<row>

<entry><function>pg_get_userbyid</>(<parameter>userid</parameter>)</entry>

<entry><type>name</></entry>

<entry>Get user name given sysid</>

</row>

</tbody>

</tgroup>

</table>

<indexterm zone="functions-misc">

<primary>version</primary>

<primary>pg_get_viewdef</primary>

</indexterm>

<indexterm zone="functions-misc">

<primary>pg_get_ruledef</primary>

</indexterm>

<indexterm zone="functions-misc">

<primary>pg_get_indexdef</primary>

</indexterm>

<indexterm zone="functions-misc">

<primary>pg_get_userbyid</primary>

</indexterm>

<para>

<function>version()</> returns a string describing the PostgreSQL

server's version.

These functions extract information from the system catalogs.

<function>pg_get_viewdef()</>, <function>pg_get_ruledef()</>, and

<function>pg_get_indexdef()</> respectively reconstruct the creating

command for a view, rule, or index. (Note that this is a decompiled

reconstruction, not the verbatim text of the command.)

<function>pg_get_userbyid()</> extracts a user's name given a

<structfield>usesysid</> value.

</para>

</sect1>