v0-0003-change-pw.patch

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index ed88ac0..5d2f70c 100644
*** a/doc/src/sgml/libpq.sgml
--- b/doc/src/sgml/libpq.sgml
*************** char *PQencryptPasswordConn(PGconn *conn
*** 7116,7121 ****
--- 7116,7167 ----
      </listitem>
     </varlistentry>
  
+    <varlistentry id="libpq-PQchangePassword">
+     <term><function>PQchangePassword</function><indexterm><primary>PQchangePassword</primary></indexterm></term>
+ 
+     <listitem>
+      <para>
+       Changes a <productname>PostgreSQL</productname> password.
+ <synopsis>
+ char *PQchangePassword(PGconn *conn, const char *passwd, const char *user, const char *algorithm);
+ </synopsis>
+       This function uses <function>PQencryptPasswordConn</function>
+       to build and execute the command <literal>ALTER USER ... PASSWORD
+       '...'</literal>, thereby changing the user's password. It exists for
+       the same reason as <function>PQencryptPasswordConn</function>, but
+       is more convenient as it both builds and runs the command for you.
+      </para>
+ 
+      <para>
+       The <parameter>passwd</parameter> and <parameter>user</parameter> arguments
+       are the cleartext password, and the SQL name of the user it is for.
+       <parameter>algorithm</parameter> specifies the encryption algorithm
+       to use to encrypt the password. Currently supported algorithms are
+       <literal>md5</literal> and <literal>scram-sha-256</literal> (<literal>on</literal> and
+       <literal>off</literal> are also accepted as aliases for <literal>md5</literal>, for
+       compatibility with older server versions). Note that support for
+       <literal>scram-sha-256</literal> was introduced in <productname>PostgreSQL</productname>
+       version 10, and will not work correctly with older server versions. If
+       <parameter>algorithm</parameter> is <symbol>NULL</symbol>, this function will query
+       the server for the current value of the
+       <xref linkend="guc-password-encryption"/> setting. That can block, and
+       will fail if the current transaction is aborted, or if the connection
+       is busy executing another query. If you wish to use the default
+       algorithm for the server but want to avoid blocking, query
+       <varname>password_encryption</varname> yourself before calling
+       <xref linkend="libpq-PQchangePassword"/>, and pass that value as the
+       <parameter>algorithm</parameter>.
+      </para>
+ 
+      <para>
+       The return value is a boolean indicating <symbol>true</symbol> for success
+       or <symbol>false</symbol> for failure. On failure a suitable message is
+       stored in the connection object.
+      </para>
+ 
+     </listitem>
+    </varlistentry>
+ 
     <varlistentry id="libpq-PQencryptPassword">
      <term><function>PQencryptPassword</function><indexterm><primary>PQencryptPassword</primary></indexterm></term>