Code RoomCounter upsert hangs intermittently

HardPrep Room Coding #1842

Counter upsert hangs intermittently

Code reviewDatabases & SQLConcurrencySenior–Staff~32 min

Review this SQL stored-procedure body (MySQL/InnoDB, REPEATABLE READ) that upserts a daily counter.

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1START TRANSACTION;

2

3SELECT count FROM daily_counters

4 WHERE day = CURDATE() AND metric = p_metric

5 FOR UPDATE;

6

7-- if no row, insert it

8INSERT INTO daily_counters (day, metric, count)

9 VALUES (CURDATE(), p_metric, 1);

10

11UPDATE daily_counters SET count = count + 1

12 WHERE day = CURDATE() AND metric = p_metric;

13

14COMMIT;

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