# Flatstore Module

Jan
Janak
FhG FOKUS
jan@iptel.org
2004
2005
FhG FOKUS
$Revision: 1.1.2.1 $
$Date: 2005/06/22 23:16:51 $

## User's Guide

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.

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.

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.

The acc module can be configured to use flatstore module as database backend using the db_url_parameter:

    modparam("acc", "db_url", "flatstore:/var/log/acc")

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.

Name of files in that directory will follow the following pattern:

    <table_name>_<process_name>.log

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.

### Rotating Log Files

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:

- Rename the files that you want to rotate:

      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
      ...

  Note that at this point SER will still be writing all data into the renamed files.

- Send SER the fifo command to close and reopen the renamed files:

      serctl fifo flat_rotate

  This will force SER to close the renamed files and open new ones with original names, such as acc_1.log. 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.

- Move the renamed files somewhere else and process them.

### Dependencies

None.

### Exported Parameters

#### `flush` (integer)

Enable or disable flushing after each write.

Default value is 1.

### Exported Functions

This module does not export any functions usable from the configuration script.