====== Update ======
{{indexmenu_n>4}}

If you have a large amount of received data, before update it is recommended to
  - Stop receivers <code>fastor-stop</code>
  - Wait for the completion of inserts into the database <code>clickhouse-client --query="select * from system.processes sp where sp.query like 'insert into%'" | wc -l</code>
  - Stop DB <code>fastor-db-stop</code>

Updating is performed using the same scripts as in the [[dpi:dpi_components:qoestor:install_and_update:install|Installation]] section. 


<note important>In some systems, the database starts very slowly (from several minutes to several tens of minutes, especially in systems with long-term data storage) and when updating you may receive an error like **ERROR: while updating DB scheme**

{{:dpi:dpi_components:qoestor:dbcheme_update_err.png?600|}}

Wait for the database to start. You can check the tail /var/log/clickhouse-server/clickhouse-server.log logs, or simply try to launch the clickhouse-client client - if there is a connection, then the database has started and is ready for connections.


After starting the database, run the command <code>fastor-db-scheme</code>
</note>
<note important>Do not forget to execute <code>fastor-db-scheme</code> after update. This insures cases when the schema does not have time to update as a result of a long restart of the database. </note>

<note warning>If QoE Stor is installed on CentOS 7, use the [[dpi:dpi_components:qoestor:install_and_update:update:centos7]] guide.</note>