事务期间不会阻止SQL UPDATE / INSERTS

Question

I have a table where it is constantly being sent UPDATES/INSERTS from other processes, and I am trying to perform a transaction to my SQL table where I rotate the table and move some of the last values into the new table that I just created:

BEGIN TRANSACTION;
CREATE TABLE temp LIKE sales;
RENAME TABLE sales TO sales_05_04_19, temp TO sales
INSERT INTO sales SELECT * FROM sales_05_04_19 WHERE time > 1556953200000;
COMMIT;

But it does not appear to be blocking these UPDATES/INSERTS and some seem to actually make it through to the newly created sales table before the transaction's INSERT occurs. This causes me to get the error on the transaction insert:

(1062, "Duplicate entry '1' for key 'PRIMARY'")

I thought that this transaction would block the UPDATES/INSERTS until it commits, but that doesn't seem to be the case here. So I feel that I would need to acquire a lock. How would I go about doing this (if that is the right approach to fixing this)?

Answer 1

If you want to prevent updates on a table while you do this kind of thing, you'll need to LOCK TABLES rather than use a transaction. I suggest creating your new table, locking both it and the old one, doing the rename switcheroo, doing your insert, then releasing the locks. There is no need for the transaction. Transactions avoid inconsistency, but they do not guarantee order, and DDL statements like create and rename table are not transaction-safe in any case.