How to Find the Most Recent Records for Each Method and ID Combination in MySQL?

How to Select the Most Recent Records for Combinations of Fields in a MySQL Table

The provided MySQL table, rpc_responses, stores responses to RPC calls with fields including timestamp, method, id, and response. The goal is to retrieve the most recent responses for distinct combinations of method and id.

To achieve this, we can leverage MySQL's ROW_NUMBER() function with a windowing clause:

SELECT *
FROM (
    SELECT *, 
            ROW_NUMBER() OVER (PARTITION BY method, id ORDER BY timestamp DESC) AS row_num
    FROM rpc_responses
) AS subquery
WHERE row_num = 1

This query uses a subquery to calculate the row number for each distinct combination of method and id, ordered in descending order by the timestamp field. The outer query then filters the results to select only the rows with row number 1, which represents the most recent record for each combination.

This approach should efficiently retrieve the desired data without the need for complex joins or temporary tables.

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