== Onyx Export and Purge ==

=== Sources of Info ===
The Onyx User Guide has a useful Chapter 12 "Topics for System Administrators" with details of the export and purge functions. 

 * The User Guide can be found here http://wiki.obiba.org/confluence/display/ONYX/Onyx+User+Guide 

Other useful links to the obiba wiki
 * Configuring export and purge http://wiki.obiba.org/confluence/display/ONYX16x/Configuring+Data+Export+and+Purge
 * Data Exportation from Onyx. Interesting, but don't know how up to date: http://wiki.obiba.org/confluence/display/ONYX/Data+Exportation+from+Onyx 
 * Onyx Variables: http://wiki.obiba.org/confluence/display/ONYX/Onyx+Variables

=== Overview ===

'''Exporting data''' from Onyx means reading data from the Onyx database and writing it to one or more export destinations. Exporting does not delete any data from the Onyx database. Deleting data from the database is done by the purge function. An export destination is a compressed zip file. Participant data and experimental conditions data can be exported. Configuration of data export is done entirely in configuration files, not through the Onyx user interface. Some things that can be configured:
 * Which data is selected for export
 * Directory to which export files are written
 * How many export destinations are defined

NB: Only system administrators can execute a data export from the Onyx user interface. My understanding is that this means an export is triggered from the user interface. 

'''Purging data''' means deleting data from the Onyx database. Only participant data can be purged — not experimental conditions data.
Configuration of data purging is done entirely in configuration files, not through the Onyx user interface. As per data export, only a system administrator can execute a purge of data by a function from within the user interface.

=== Sample Config Export File and resulting Export Zip File ===