# Db_flatstore Module

## Admin Guide

### Overview

Db_flatstore is one of the &kamailio; 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 modules can use it as a database driver, instead of, for example, the db_mysql module.

The module does not implement all functions of the database API, it supports only one function, insert. This means that 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. Please note that the acc module is the only module that was tested with the flatstore module.

The format of the files produced by this module is plain text. Each line consists of several fields, fields are separated by the "|" character (vertical bar). 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 db_flatstore module as database backend using the db_url_parameter:

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

This configuration option tells the acc module that it should use the db_flatstore module and the db_flatstore module should create all files in the /var/log/acc directory. The directory must exist and &kamailio; 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 written by the &kamailio; process 8 into the acc table would be written in file acc_8.log. For each table there will be several files, one file for every &kamailio; 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 &kamailio; 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

The module implements a &kamailio; management interface command called flatstore.k_rotate. When &kamailio; receives the command it will close and reopen all files used by the db_flatstore module. The rotation itself has to be done by another application (such as logrotate). Follow these steps to rotate files generated by the db_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 &kamailio; will still be writing all data into the renamed files.

- Send &kamailio; the management command to close and reopen the renamed files:

      &sercmd; flatstore.k_rotate

  This will force &kamailio; 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 &kamailio; has some data to write. It is normal that the files will be not created immediately if there is no traffic on the SIP server.

- Move the renamed files somewhere else and process them.