..When using a Streaming method (HTTP Stream API, Kafka, AWS Kinesis) to ingest data, Hydrolix provides several customisations for how and when data is written into the table and for using stream authentication.

Configuring How and When Data is Written

When using a Streaming method (HTTP Stream API, Kafka, AWS Kinesis) to ingest data, Hydrolix provides several customisations in how and when data is written into the table.

These customisations are provided as streaming event data often has the characteristics of containing "Hot" data that needs to be made available as soon as possible, and "cold" data that arrives late or out of order. A good example of this are CDN or appliance logs where 95% of logs are provided within a 15 minutes window with the last 5% being supplied later in a 24 hour period.

Settings for Hot and Cold data can be independently configured and cover a variety of "tunables" that determine how often event partitions are flushed to storage and how many partitions are being worked on at any one time.

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Defaults

It is recommended that before changing settings the defaults be used initially. The default settings have been developed to meet the majority of use cases.

Configuring Data Write Settings

The settings for how data is written to the table are configured either through the portal and under the sources menu or via the Restful API - Tables.

To effectively manage incoming stream data, Hydrolix Streaming has configurable options for Hot and Cold data.

• Hot data is near-term data defined as an event received within the hot_data_max_age_minutes window from now().
• Cold data is defined as data that is late arriving event data that is beyond the hot_data_max_age_minutes but before the cold_data_max_age_days.
• Data beyond the cold_data_max_age_days, it is rejected and ignored.

Hot Settings

The following settings define Hot data behavior:

Cold Settings

The following settings define Cold data behavior:

Other Settings

The following settings define all data behavior, hot and cold:

Configuring Stream Authentication Settings

By default, the traefik service uses basic authentication. But Hydrolix also supports token-based authentication for tables. When enabled, API function calls require a token to be passed in the query string or a HTTP header. Hydrolix only performs the operation if the token matches one of the tokens defined for the table.

To enable token-based authentication, set the following values in the stream field of your table settings:

• set token_auth_enabled to true in the stream settings of the table
• set token_list to an array of tokens. This allows for easy token rotations as well as using multiple tokens at the same time.

The following snippet shows a full example of a stream authentication configuration for a table:

"settings": {
  ...
  "stream": {
    "token_auth_enabled": true,
    "token_list": ['token1', 'token2']
  }
  ...
}

Configuring via the API

To configure the table via the API the Tables API endpoints are used.

The following is an example:

POST 'http://myhost/config/v1/orgs/my_org_uuid/projects/my_project_uuid/tables/

{
      "project": "{{project_uuid}}",
      "name": "mytable",
      "description": "An example table",
      "settings": {
         "stream": {
            "hot_data_max_age_minutes": 15,
            "hot_data_max_active_partitions": 4,
            "hot_data_max_rows_per_partition": 1000000,
            "hot_data_max_minutes_per_partition": 5,
            "hot_data_max_open_seconds": 60,
            "hot_data_max_idle_seconds": 30,
            "cold_data_max_age_days": 365,
            "cold_data_max_active_partitions": 5,
            "cold_data_max_rows_per_partition": 1000000,
            "cold_data_max_minutes_per_partition": 15,
            "cold_data_max_open_seconds": 60,
            "cold_data_max_idle_seconds": 30
         }
      }
}

Interdependence with Merge.

More information on merge can be found here. It should be noted that the volume of partitions written directly by the Stream affects the merge service - i.e. more/less partitions to merge later.

Where a higher number of partitions are being created during the initial ingest stream it is important to ensure there are a sufficient amount of merge peers created to merge the resultant data. A higher partition count in the initial loading process may require higher counts (or size) of merge servers.