Retrieve the Latest Record for Each Group

WITH LatestRecords AS (
    SELECT
        id,
        group_id,
        event_timestamp,
        data_column,
        ROW_NUMBER() OVER (PARTITION BY group_id ORDER BY event_timestamp DESC) as rn
    FROM
        your_table
)
SELECT
    id,
    group_id,
    event_timestamp,
    data_column
FROM
    LatestRecords
WHERE
    rn = 1;

How it works: This SQL snippet uses a Common Table Expression (CTE) and the `ROW_NUMBER()` window function to identify the latest record for each distinct `group_id`. `PARTITION BY group_id` divides the dataset into groups based on the `group_id`, and `ORDER BY event_timestamp DESC` sorts records within each group by their `event_timestamp` in descending order. `ROW_NUMBER()` then assigns a sequential number to each record within its partition, with `1` indicating the latest entry. The outer query subsequently selects only those records where `rn = 1`, effectively retrieving the most recent record for each group.