.. _FlowsDump:

Flows Dump
##########

Ntopng supports flows dump towards multiple downstream databases, namely MySQL, Elasticsearch, Syslog and ClickHouse. Flows dump is enabled using option :code:`-F`.

.. note::

  ClickHouse support is the recommended database backend used to dump flows and alerts.

When flows dump is enabled, a new `Flow Dump Settings` tab appears in the preferences.

.. figure:: ../img/advanced_features_flows_dump_setting.png
  :align: center
  :alt: Flows Dump Settings

  Flows Dump Settings

`Flow Dump Settings` entries are:

- `Flows Dump`: to toggle the dump of flows during the execution of ntopng. Flows dump can be turned on or off using this toggle. Turning flows dump off may be useful when the destination downstream database is running out of space, for debug purposes, or when the user only wants alerts stored in :ref:`ElasticsearchAlerts`.
- `Tiny Flows Dump`: to toggle the dump of tiny flows. Tiny flows are small flows, that is, flows totalling less than a certain configurable number of packets or bytes. Excluding tiny flows from the dump is an effective strategy to reduce the number of dumped flows. This reduction is mostly effective when dumped flows are used to do analyses based on the volume. It is not recommended to use this option when dumped flows are used for security analyses.
- `Maximum Number of Packets per Tiny Flow`: is used to configure the maximum number of packets a flow must have to be considered tiny.
- `Maximum Number of Bytes per Tiny Flow`: is used to configure the maximum number of bytes a flow must have to be considered tiny.
- `Limit the Number of Aggregated Flows`: allows to cap the number of aggregated flows dumped periodically when using nIndex or MySQL. MySQL and nIndex aggregate flows at 5-minute intervals to make certain queries faster. Reducing the number of aggregated flows may be useful to reduce the total number of exports performed and thus, the number of aggregated flows in the database.
- `Maximum Number of Aggregated Flows Dumped Every 5 Minutes`: is used to specify the maximum number of aggregated flows dumped every 5-minutes.

These settings are effective for all databases.

.. toctree::
    :maxdepth: 2

    clickhouse/index
    elastisearch/index
    kafka/index
    syslog/index