The name of the entity column. For Kafka sources, use dot-prefixed path notation to reference
fields within the key or value schema (e.g., "value.user_id", "key.partition_key"). For nested
fields, the leaf node name (e.g., "user_id" from "value.trip_details.user_id") is what will
be present in materialized tables and expected to match at query time.
Colon-prefixed notation (e.g., "value:user_id") is supported for backwards
compatibility but is deprecated; migrate to dot notation.
The name of the entity column. For Kafka sources, use dot-prefixed path notation to reference fields within the key or value schema (e.g., "value.user_id", "key.partition_key"). For nested fields, the leaf node name (e.g., "user_id" from "value.trip_details.user_id") is what will be present in materialized tables and expected to match at query time. Colon-prefixed notation (e.g., "value:user_id") is supported for backwards compatibility but is deprecated; migrate to dot notation.