The `pgmemento.row_log` table is the most important log table in pgMemento, because it stores the historic data a.k.a the audit trail. It only consists of four columns:
* `id BIGSERIAL`: The Primary Key
* `audit_id BIGINT NOT NULL`: The implicit link to a table's row
* `event_key TEXT`: Concatenated metadata of table event to join with `table_event_log` table
* `old_data JSONB`: The old values of changed columns in a JSONB object
* `new_data JSONB`: The old values of changed columns in a JSONB object

The `row_log` is filled by [AFTER table triggers](https://github.com/pgMemento/pgMemento/wiki/DML-logging) or some [event triggers](https://github.com/pgMemento/pgMemento/wiki/DDL-logging) e.g. in case of ALTER COLUMN or DROP COLUMN events. The `audit_id` column creates the link to each row of audited tables. It's the tracer of the audit trail.

The `event_key` column stores the transaction and statement unix timestamp as well as the internal txid, the event type, the table name and schema name. Thus, row logs can be referenced with a table event and corresponding transaction. The temporal part of the key also allows for partitioning the `row_log` table.