Allow pg_resetxlog -f to reset pg_control counters using xlog

information, and add a -r option to reset pg_control without affecting
xlog.

yuanjia lee

doc/src/sgml/ref/pg_resetxlog.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/pg_resetxlog.sgml,v 1.13 2006/04/25 21:02:33 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/pg_resetxlog.sgml,v 1.14 2006/04/26 02:17:15 momjian Exp $
 PostgreSQL documentation
 -->
 
@@ -20,6 +20,7 @@ PostgreSQL documentation
    <command>pg_resetxlog</command>
    <arg>-f</arg>
    <arg>-n</arg>
+   <arg>-r</arg>
    <arg>-o<replaceable class="parameter">oid</replaceable> </arg>
    <arg>-x <replaceable class="parameter">xid</replaceable> </arg>
    <arg>-m <replaceable class="parameter">mxid</replaceable> </arg>
@@ -57,22 +58,22 @@ PostgreSQL documentation
 
   <para>
    If <command>pg_resetxlog</command> complains that it cannot determine
-   valid data for <filename>pg_control</>, you can force it to proceed anyway
-   by specifying the <literal>-f</> (force) switch.  In this case plausible
-   values will be substituted for the missing data.  Most of the fields can be
-   expected to match, but manual assistance may be needed for the next OID,
-   next transaction ID, next multitransaction ID and offset,
-   WAL starting address, and database locale fields.
-   The first five of these can be set using the switches discussed below.
-   <command>pg_resetxlog</command>'s own environment is the source for its
-   guess at the locale fields; take care that <envar>LANG</> and so forth
-   match the environment that <command>initdb</> was run in.
-   If you are not able to determine correct values for all these fields,
-   <literal>-f</> can still be used, but
+   valid data for <filename>pg_control</>, you can force it to proceed
+   anyway by specifying the <literal>-f</> (force) switch. In this case
+   plausible values will be substituted for the missing data.
+   <command>pg_resetxlog</command>'s own environment is the source for
+   its guess at the locale fields; take care that <envar>LANG</> and so
+   forth match the environment that <command>initdb</> was run in.
+   <filename>/xlog</> files are used to determine other parameters, like
+   next OID, next transaction ID, next multi-transaction ID and offset,
+   WAL starting address, and database locale fields. Because determined
+   values might be wrong, the first five of these can be set using the
+   switches discussed below. If you are not able to determine correct
+   values for all these fields, <literal>-f</> can still be used, but
    the recovered database must be treated with even more suspicion than
-   usual: an immediate dump and reload is imperative.  <emphasis>Do not</>
-   execute any data-modifying operations in the database before you dump;
-   as any such action is likely to make the corruption worse.
+   usual: an immediate dump and reload is imperative. <emphasis>Do
+   not</> execute any data-modifying operations in the database before
+   you dump; as any such action is likely to make the corruption worse.
   </para>
 
   <para>
@@ -149,6 +150,11 @@ PostgreSQL documentation
    </itemizedlist>
   </para>
 
+  <para>
+   The <literal>-r</> restores <filename>pg_control</> counters listed
+   above without resetting the write-ahead log.
+  </para>
+
   <para>
    The <literal>-n</> (no operation) switch instructs
    <command>pg_resetxlog</command> to print the values reconstructed from