content/integrate/write-behind/data-transformation/_index.md
The key functionality that Write-behind performs is mapping the data coming from Debezium Server (representing a Source Database row data or row state change) into a Redis key with a value of [Hash]({{< relref "/develop/data-types/hashes" >}}) or [JSON]({{< relref "/develop/data-types/json/" >}}). There are two types of data transformations in Write-behind:
By default, each source row is converted into one hash or one JSON key in Redis. This conversion uses the Debezium schema-based conversion. The incoming data includes the schema and Write-behind uses a set of handlers to automatically convert each source column to a Redis Hash field or JSON type based on the Debezium type in the schema. See [data type conversion]({{< relref "/integrate/write-behind/reference/data-types-conversion" >}}) for a full reference on these conversions.
If the user wants to add or modify this default mapping, Write-behind provides declarative data transformations. These transformations are represented in YAML files. Each file contains a job, which is a set of transformations per source table. See [declarative transformations]({{< relref "/integrate/write-behind/data-transformation/data-transformation-pipeline" >}}) for more information.
{{< image filename="/images/rdi/data-transformation-flow.png" >}}