How to select the most recent set of dated records from a mysql table

Posted by Ken on Stack Overflow See other posts from Stack Overflow or by Ken
Published on 2009-01-12T15:11:08Z Indexed on 2010/06/06 9:32 UTC
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mysql

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date

I am storing the response to various rpc calls in a mysql table with the following fields:

Table: rpc_responses

timestamp   (date)
method      (varchar)
id          (varchar)
response    (mediumtext)

PRIMARY KEY(timestamp,method,id)

What is the best method of selecting the most recent responses for all existing combinations of method and id?

For each date there can only be one response for a given method/id.
Not all call combinations are necessarily present for a given date.
There are dozens of methods, thousands of ids and at least 356 different dates

Sample data:

timestamp  method  id response
2009-01-10 getThud 16 "....."
2009-01-10 getFoo  12 "....."
2009-01-10 getBar  12 "....."
2009-01-11 getFoo  12 "....."
2009-01-11 getBar  16 "....."

Desired result:

2009-01-10 getThud 16 "....."
2009-01-10 getBar 12 "....."
2009-01-11 getFoo 12 "....."
2009-01-11 getBar 16 "....."

(I don't think this is the same question - it won't give me the most recent response)

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