MySQL 8.0

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CREATE TABLE tab( id INT, timestamp TIMESTAMP, metric VARCHAR(10), value INT);
INSERT INTO tab VALUES
(1, '2020-10-31 02:52:02.144030', 'aaaa', 3),
(2, '2020-10-31 02:52:02.144030', 'tttt', 40),
(3, '2020-10-31 02:52:02.144030', 'vvvv', 6),
(4, '2020-10-31 02:53:01.656349', 'aaaa', 3),
(5, '2020-10-31 02:53:01.656349', 'tttt', 40),
(6, '2020-10-31 02:53:01.656349', 'vvvv', 6)
SET @sql = NULL;

SELECT GROUP_CONCAT(
             CONCAT(
                    'MAX(CASE WHEN metric = "', metric,'" THEN value END ) AS ',metric
                    )
       )
  INTO @sql
  FROM ( SELECT DISTINCT metric FROM tab) t;

SET @sql = CONCAT('SELECT timestamp,',@sql,' FROM tab GROUP BY timestamp'); 

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;


timestamp
aaaa
tttt
vvvv


2020-10-31 02:52:02
3
40
6

2020-10-31 02:53:02
3
40
6