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Aug 29, 2022 · Databases

Why Parallel DELETEs on a MySQL Table Trigger Lock Wait Timeouts

When trying to change a table’s primary key from int to bigint, a 500‑million‑row MySQL table required data archiving and a bulk MODIFY, but parallel DELETE statements caused lock‑wait timeouts; experiments reveal that under REPEATABLE READ the range scan locks the boundary row, leading to contention.