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<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
-
- This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
- project.
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- Copyright (C) 1998-2018 OpenLink Software
-
- This project is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by the
- Free Software Foundation; only version 2 of the License, dated June 1991.
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- This program is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
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- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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-->
<refentry id="fn_backup">
<refmeta>
<refentrytitle>backup</refentrytitle>
<refmiscinfo>backup</refmiscinfo>
</refmeta>
<refnamediv>
<refname>backup</refname>
<refname>backup_close</refname>
<refname>backup_flush</refname>
<refname>backup_prepare</refname>
<refname>backup_row</refname>
<refpurpose>Write data into transaction log format for backup purposes. Deprecated. </refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis id="fsyn_backup">
<funcprototype id="fproto_backup">
<funcdef><function>backup</function></funcdef>
<paramdef>in <parameter>file</parameter> varchar</paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis id="fsyn_backup_close">
<funcprototype id="fproto_backup_close">
<funcdef><function>backup_close</function></funcdef>
<paramdef></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis id="fsyn_backup_flush">
<funcprototype id="fproto_backup_flush">
<funcdef><function>backup_flush</function></funcdef>
<paramdef></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis id="fsyn_backup_prepare">
<funcprototype id="fproto_backup_prepare">
<funcdef><function>backup_prepare</function></funcdef>
<paramdef>in <parameter>file</parameter> varchar</paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis id="fsyn_backup_row">
<funcprototype id="fproto_backup_row">
<funcdef><function>backup_row</function></funcdef>
<paramdef>in <parameter>row</parameter> any</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="desc_backup">
<title>Description</title>
<important>
<para>
These functions are deprecated. The use of backup_online () is preferred for database backups.
Performing a backup with the destination file /dev/null is a good way of verifying a database's physical integrity.
</para>
<para>All backup files, whether complete (created with
<function>backup</function>) or partial (created with
<function>backup_prepare</function> and <function>backup_row</function>
of selected rows), begin with the complete schema that was effective at
the time of the backup.</para>
<para>Backup and log files contain assumptions about the schema and row
layout of the database. Hence it is not possible to use these for
transferring data between databases. Attempt to do so will result in
unpredictable results. Thus a log or backup may only be replayed on
the same database, an empty database or a copy of the database which
has had no schema changed since it was made.
Also, when replaying a backup file onto an empty database, the +replay-crash-dump switch should be given on the executable command line.
</para></important>
<para>This function requires dba privileges.</para>
<refsect2><title>Full backup</title>
<para>The <function>backup</function> function takes a file name as
argument. The file produced will be in the log format and will recreate
the database as it was at the time of the last checkpoint when replayed
on an empty database. Such a file cannot be replayed on anything except
an empty database. Logs made after the backup can be replayed over the
database resulting from the backup file's replay. No schema operations
are allowed between replays.</para>
</refsect2>
<refsect2>
<title>Partial backups</title>
<para>The <function>backup_prepare</function>,
<function>backup_row</function> and <function>backup_close</function>
operations allow making specific partial backups.</para>
<formalpara><title><function>backup_prepare</function></title>
<para><function>backup_prepare</function> initiates the backup. This
must be the first statement to execute in its transaction. The
rest of the transaction will be a read only snapshot view of the state
as of the last checkpoint. Checkpointing is disabled until
<function>backup_close</function> is called.</para>
</formalpara>
<para>Checkpoints are disabled for the time between
<function>backup_prepare</function> and
<function>backup_close</function>. The backup transaction being
lock-free, it cannot die of deadlock and hence will stay open for the
duration of the backup.</para>
<formalpara><title><function>backup_row</function></title>
<para><function>backup_row</function> writes the row given as
parameter into the backup file that was associated to the current
transaction by a prior <function>backup_prepare</function>. The row
must be obtained obtained by selecting the pseudo column
<varname>_ROW</varname> from any table.</para>
</formalpara>
<formalpara><title><function>backup_flush</function></title>
<para>The <function>backup_flush</function> function will insert a
transaction boundary into the backup log. All rows backed up between
two <function>backup_flush</function> calls will be replayed as a
single transaction by replay. Having long intervals between
<function>backup_flush</function> calls will cause significant memory
consumption at replay time for undo logs.</para>
</formalpara>
<formalpara><title><function>backup_close</function></title>
<para>The <function>backup_close</function> function terminates the
backup and closes the file. The transaction remains a read only
snapshot of the last checkpoint but checkpoints are now re-enabled.
The transaction should be committed or rolled back after
<function>backup_close</function>.</para>
</formalpara>
</refsect2>
</refsect1>
<refsect1 id="params_backup"><title>Parameters</title>
<refsect2><title><parameter>file</parameter></title>
<para><type>varchar</type> <parameter>file</parameter> filename for
the generated log.</para>
</refsect2>
<refsect2><title><function>backup_row</function></title>
<para><type>any</type> <parameter>row</parameter> a value of the pseudo
column <varname>_ROW</varname>.</para>
</refsect2>
</refsect1>
<refsect1 id="seealso_backup"><title>See Also</title>
<para><link linkend="fn_replay">replay</link></para>
<para><link linkend="fn_backup_online"><function>backup_online()</function></link>,
<link linkend="fn_backup_context_clear"><function>backup_context_clear()</function></link></para>
</refsect1>
</refentry>
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