First-Last

First-Last features are great for enrichments of fields from one-to-many relations. It is commonly used to enrich an entity with fields of the first or last appearance of a one-to-many related assets or entities.

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Simple first-last feature

In this example, we define simple first-last features for the entity customer:

# customer.yml

features:
- type: first_last
  name: last_call_agent_id
  data_type: string
  asset: db_prod.core.phone_call_dim
  options:
    method: last
    sort_by: created_at
    field: agent_id
  filters: null

type

The feature type. In case of first-last features, it should be set to first_last.

name

Give the feature a name.

asset

The data asset with the field to be added as feature to our entity. asset should be the full path: "db.schema.name".

asset has to be related to our entity (see related data asset).

join_name [optional]

In case multiple join patterns are defined between an entity and a data asset, join_name is used to determine which join path to use for a specific feature.

For more information about using multiple join paths between an entity and a data asset, visit the related data assets page.

data_type [optional]

Specify the feature data type. If no data_type specified, Lynk will assume the data type is string.

The options for data types are:

string

For any type of string data type

number

For any type of number data type. For example: integer, float, decimal etc..

datetime

For any type of time-based data type. For example: date, timestamp, datetime etc..

bool

For boolean data type.

time_field [optional]

Specifies which asset time field to use in case of time-based aggregation is applied to the first-last feature. If not specified, Lynk will use the asset's default time_field.

See time aggregation for more information on how time fields are being used for time-based feature aggregations.

options

The options for the first-last definitions on which field we would like to get and how to sort the related data asset

method

Determines which instance of the data asset to retrieve - the first or the last, based on the sort_by option.

sort_by

The data asset field to sort by.

field

The name of the data asset field to retrieve as the entity feature.

filters

Custom filters to be applied on the data asset. See filters page for in depth information on how to apply filters.