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| -rw-r--r-- | doc/src/sgml/ref/pg_resetxlog.sgml | 222 |
1 files changed, 144 insertions, 78 deletions
diff --git a/doc/src/sgml/ref/pg_resetxlog.sgml b/doc/src/sgml/ref/pg_resetxlog.sgml index 1bcc5a7ff03..fd9d0be6f44 100644 --- a/doc/src/sgml/ref/pg_resetxlog.sgml +++ b/doc/src/sgml/ref/pg_resetxlog.sgml @@ -22,15 +22,9 @@ PostgreSQL documentation <refsynopsisdiv> <cmdsynopsis> <command>pg_resetxlog</command> - <arg choice="opt"><option>-c</option> <replaceable class="parameter">xid</replaceable>,<replaceable class="parameter">xid</replaceable></arg> <arg choice="opt"><option>-f</option></arg> <arg choice="opt"><option>-n</option></arg> - <arg choice="opt"><option>-o</option> <replaceable class="parameter">oid</replaceable></arg> - <arg choice="opt"><option>-x</option> <replaceable class="parameter">xid</replaceable></arg> - <arg choice="opt"><option>-e</option> <replaceable class="parameter">xid_epoch</replaceable></arg> - <arg choice="opt"><option>-m</option> <replaceable class="parameter">mxid</replaceable>,<replaceable class="parameter">mxid</replaceable></arg> - <arg choice="opt"><option>-O</option> <replaceable class="parameter">mxoff</replaceable></arg> - <arg choice="opt"><option>-l</option> <replaceable class="parameter">xlogfile</replaceable></arg> + <arg rep="repeat"><replaceable>option</replaceable></arg> <arg choice="req"><arg choice="opt"><option>-D</option></arg> <replaceable class="parameter">datadir</replaceable></arg> </cmdsynopsis> </refsynopsisdiv> @@ -76,78 +70,108 @@ PostgreSQL documentation execute any data-modifying operations in the database before you dump, as any such action is likely to make the corruption worse. </para> + </refsect1> - <para> - The <option>-o</>, <option>-x</>, <option>-e</>, - <option>-m</>, <option>-O</>, - <option>-c</> - and <option>-l</> - options allow the next OID, next transaction ID, next transaction ID's - epoch, next and oldest multitransaction ID, next multitransaction offset, - oldest and newest transaction IDs for which the commit time can be retrieved, - and WAL - starting address values to be set manually. These are only needed when - <command>pg_resetxlog</command> is unable to determine appropriate values - by reading <filename>pg_control</>. Safe values can be determined as - follows: + <refsect1> + <title>Options</title> - <itemizedlist> + <variablelist> + <varlistentry> + <term><option>-f</option></term> <listitem> <para> - A safe value for the next transaction ID (<option>-x</>) - can be determined by looking for the numerically largest - file name in the directory <filename>pg_clog</> under the data directory, - adding one, - and then multiplying by 1048576. Note that the file names are in - hexadecimal. It is usually easiest to specify the option value in - hexadecimal too. For example, if <filename>0011</> is the largest entry - in <filename>pg_clog</>, <literal>-x 0x1200000</> will work (five - trailing zeroes provide the proper multiplier). + Force <command>pg_resetxlog</command> to proceed even if it cannot determine + valid data for <filename>pg_control</>, as explained above. </para> </listitem> + </varlistentry> + <varlistentry> + <term><option>-n</option></term> <listitem> <para> - A safe value for the next multitransaction ID (first part of <option>-m</>) - can be determined by looking for the numerically largest - file name in the directory <filename>pg_multixact/offsets</> under the - data directory, adding one, and then multiplying by 65536. - Conversely, a safe value for the oldest multitransaction ID (second part of - <option>-m</>) - can be determined by looking for the numerically smallest - file name in the same directory and multiplying by 65536. - As above, the file names are in hexadecimal, so the easiest way to do - this is to specify the option value in hexadecimal and append four zeroes. + The <option>-n</> (no operation) option instructs + <command>pg_resetxlog</command> to print the values reconstructed from + <filename>pg_control</> and values about to be changed, and then exit + without modifying anything. This is mainly a debugging tool, but can be + useful as a sanity check before allowing <command>pg_resetxlog</command> + to proceed for real. </para> </listitem> + </varlistentry> + <varlistentry> + <term><option>-V</option></term> + <term><option>--version</option></term> + <listitem><para>Display version information, then exit.</para></listitem> + </varlistentry> + + <varlistentry> + <term><option>-?</option></term> + <term><option>--help</option></term> + <listitem><para>Show help, then exit.</para></listitem> + </varlistentry> + </variablelist> + + <para> + The following options are only needed when + <command>pg_resetxlog</command> is unable to determine appropriate values + by reading <filename>pg_control</>. Safe values can be determined as + described below. For values that take numeric arguments, hexadecimal + values can be specified by using the prefix <literal>0x</literal>. + </para> + + <variablelist> + <varlistentry> + <term><option>-c</option> <replaceable class="parameter">xid</replaceable>,<replaceable class="parameter">xid</replaceable></term> <listitem> <para> - A safe value for the next multitransaction offset (<option>-O</>) - can be determined by looking for the numerically largest - file name in the directory <filename>pg_multixact/members</> under the - data directory, adding one, and then multiplying by 52352. As above, - the file names are in hexadecimal. There is no simple recipe such as - the ones above of appending zeroes. + Manually set the oldest and newest transaction IDs for which the commit + time can be retrieved. </para> - </listitem> - <listitem> <para> A safe value for the oldest transaction ID for which the commit time can - be retrieved (first part of <option>-c</>) can be determined by looking + be retrieved (first part) can be determined by looking for the numerically smallest file name in the directory <filename>pg_commit_ts</> under the data directory. Conversely, a safe value for the newest transaction ID for which the commit time can be - retrieved (second part of <option>-c</>) can be determined by looking for - the numerically greatest file name in the same directory. As above, the - file names are in hexadecimal. + retrieved (second part) can be determined by looking for the numerically + greatest file name in the same directory. The file names are in + hexadecimal. </para> </listitem> + </varlistentry> + <varlistentry> + <term><option>-e</option> <replaceable class="parameter">xid_epoch</replaceable></term> <listitem> <para> - The WAL starting address (<option>-l</>) should be + Manually set the next transaction ID's epoch. + </para> + + <para> + The transaction ID epoch is not actually stored anywhere in the database + except in the field that is set by <command>pg_resetxlog</command>, + so any value will work so far as the database itself is concerned. + You might need to adjust this value to ensure that replication + systems such as <application>Slony-I</> and + <application>Skytools</> work correctly — + if so, an appropriate value should be obtainable from the state of + the downstream replicated database. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-l</option> <replaceable class="parameter">xlogfile</replaceable></term> + <listitem> + <para> + Manually set the WAL starting address. + </para> + + <para> + The WAL starting address should be larger than any WAL segment file name currently existing in the directory <filename>pg_xlog</> under the data directory. These names are also in hexadecimal and have three parts. The first @@ -168,46 +192,81 @@ PostgreSQL documentation </para> </note> </listitem> + </varlistentry> + + <varlistentry> + <term><option>-m</option> <replaceable class="parameter">mxid</replaceable>,<replaceable class="parameter">mxid</replaceable></term> + <listitem> + <para> + Manually set the next and oldest multitransaction ID. + </para> + + <para> + A safe value for the next multitransaction ID (first part) can be + determined by looking for the numerically largest file name in the + directory <filename>pg_multixact/offsets</> under the data directory, + adding one, and then multiplying by 65536 (0x10000). Conversely, a safe + value for the oldest multitransaction ID (second part of + <option>-m</>) can be determined by looking for the numerically smallest + file name in the same directory and multiplying by 65536. The file + names are in hexadecimal, so the easiest way to do this is to specify + the option value in hexadecimal and append four zeroes. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term><option>-o</option> <replaceable class="parameter">oid</replaceable></term> <listitem> <para> + Manually set the next OID. + </para> + + <para> There is no comparably easy way to determine a next OID that's beyond the largest one in the database, but fortunately it is not critical to get the next-OID setting right. </para> </listitem> + </varlistentry> + <varlistentry> + <term><option>-O</option> <replaceable class="parameter">mxoff</replaceable></term> <listitem> <para> - The transaction ID epoch is not actually stored anywhere in the database - except in the field that is set by <command>pg_resetxlog</command>, - so any value will work so far as the database itself is concerned. - You might need to adjust this value to ensure that replication - systems such as <application>Slony-I</> and - <application>Skytools</> work correctly — - if so, an appropriate value should be obtainable from the state of - the downstream replicated database. + Manually set the next multitransaction offset. </para> - </listitem> - </itemizedlist> - </para> - <para> - The <option>-n</> (no operation) option instructs - <command>pg_resetxlog</command> to print the values reconstructed from - <filename>pg_control</> and values about to be changed, and then exit - without modifying anything. This is mainly a debugging tool, but can be - useful as a sanity check before allowing <command>pg_resetxlog</command> - to proceed for real. - </para> + <para> + A safe value can be determined by looking for the numerically largest + file name in the directory <filename>pg_multixact/members</> under the + data directory, adding one, and then multiplying by 52352 (0xCC80). + The file names are in hexadecimal. There is no simple recipe such as + the ones for other options of appending zeroes. + </para> + </listitem> + </varlistentry> - <para> - The <option>-V</> and <option>--version</> options print - the <application>pg_resetxlog</application> version and exit. The - options <option>-?</> and <option>--help</> show supported arguments, - and exit. - </para> + <varlistentry> + <term><option>-x</option> <replaceable class="parameter">xid</replaceable></term> + <listitem> + <para> + Manually set the next transaction ID. + </para> + <para> + A safe value can be determined by looking for the numerically largest + file name in the directory <filename>pg_clog</> under the data directory, + adding one, + and then multiplying by 1048576 (0x100000). Note that the file names are in + hexadecimal. It is usually easiest to specify the option value in + hexadecimal too. For example, if <filename>0011</> is the largest entry + in <filename>pg_clog</>, <literal>-x 0x1200000</> will work (five + trailing zeroes provide the proper multiplier). + </para> + </listitem> + </varlistentry> + </variablelist> </refsect1> <refsect1> @@ -224,4 +283,11 @@ PostgreSQL documentation </para> </refsect1> + <refsect1> + <title>See Also</title> + + <simplelist type="inline"> + <member><xref linkend="app-pgcontroldata"></member> + </simplelist> + </refsect1> </refentry> |