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<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" 
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<section id="flatstore" xmlns:xi="http://www.w3.org/2001/XInclude">
    <sectioninfo>
	<authorgroup>
	    <author>
		<firstname>Jan</firstname>
		<surname>Janak</surname>
		<affiliation><orgname>FhG FOKUS</orgname></affiliation>
		<email>jan@iptel.org</email>
	    </author>
	</authorgroup>
	<copyright>
	    <year>2004</year>
	    <year>2005</year>
	    <holder>FhG FOKUS</holder>
	</copyright>
	<revhistory>
	    <revision>
		<revnumber>$Revision: 1.3 $</revnumber>
		<date>$Date: 2005/08/24 22:26:18 $</date>
	    </revision>
	</revhistory>
    </sectioninfo>

    <title>Flatstore Module</title>

    <section id="flatstore.overview">
	<title>Overview</title>
	<para>
	    Flatstore is one of so-called SER database modules. It does not
	    export any functions executable from the configuration scripts, but
	    it exports a subset of functions from the database API and thus
	    other module can use it instead of, for example, mysql module.
	</para>
	<para>
	    The module does not export all functions of the database API, it
	    supports only one function, insert. The module is limited but very
	    fast. It is especially suitable for storing accounting information
	    on sites with extremely high traffic. If MySQL is too slow or if
	    you get a huge amount of accounting data then you can consider
	    using this module. Note that the acc module is the only module that
	    was tested with flastore.
	</para>
	<para>
	    The format of the files produced by this module is plain text. Each
	    line consists of several fields, fields are separated by |
	    character. New information is always appended at the end of the
	    file, searching, deleting and updating of existing data is not
	    supported by the module.
	</para>
	<para>
	    The acc module can be configured to use flatstore module as
	    database backend using the db_url_parameter:
	</para>
	<programlisting>
modparam("acc", "db_url", "flatstore:/var/log/acc")
	</programlisting>
	<para>
	    This configuration options tells acc module that it should use the
	    flatstore module and the flatstore module should create all files
	    in /var/log/acc directory. The directory must exist and SER
	    processes must have permissions to create files in that directory.
	</para>
	<para>
	    Name of files in that directory will follow the following pattern:
	</para>
	<programlisting>
&lt;table_name&gt;_&lt;process_name&gt;.log
	</programlisting>
	<para>
	    For example, entries writen by SER process 8 into acc table would
	    be written in file acc_8.log. For each table there will be several
	    files, one file for every SER process that wrote some data into
	    that table. The main reason why there are several files for each
	    table is that it is much faster to have one file per process,
	    because it does not require any locking and thus SER processes will
	    not block each other. To get the complete data for a table you can
	    simply concatenate the contents of files with the same table name
	    but different process id.
	</para>
	<section id="rotating">
	    <title>Rotating Log Files</title>
	    <para>
		There is a new SER FIFO interface command called flat_rotate.
		When SER receives the command then it will close and reopen all
		files used by flatstore module. The rotation itself has to be
		done by another application (such as logrotate). Follow these
		steps to rotate files generated by flatstore module:
	    </para>
	    <itemizedlist>
		<listitem>
		    <para>
			Rename the files that you want to rotate:
			<screen>
cd /var/log/acc
mv acc_1.log acc_1.log.20050605
mv acc_2.log acc_2.log.20050605
mv acc_4.log acc_3.log.20050605
...
			</screen>
			Note that at this point SER will still be writing all
			data into the renamed files.
		    </para>
		</listitem>
		<listitem>
		    <para>
			Send SER the fifo command to close and reopen the
			renamed files:
			<screen>
serctl fifo flat_rotate
			</screen>
			This will force SER to close the renamed files and open
			new ones with original names, such as
			<filename>acc_1.log</filename>. New files will be open
			at the point when SER has some data to write. It is
			normal that the files will be not created immediately
			if there is no traffic on the proxy server.
		    </para>
		</listitem>
		<listitem>
		    <para>
			Move the renamed files somewhere else and process them.
		    </para>
		</listitem>
	    </itemizedlist>
	</section>
    </section>

    <xi:include href="params.xml"/>

</section>
