Mysql InnoDB Transaction - Why does a SELECT lock the table?

threads

[jezzer300]

I have
- Mysql 4.0.2a
- InnoDB using the default isolation type: repeatable read
- My table (x_cart) is InnoDB and Sequence row (auto_increament) is an index.

Why does my first thread cause my second thread to wait until it's done a commit?

Thread 1 first does this...

START TRANSACTION;
SELECT * from x_cart where sequence=1;

Thread 2 then does this before thread 1 commits:

START TRANSACTION;
SELECT * from x_cart where sequence=13;

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I'm not even asked the row to be locked "FOR UPDATE", so why does the 2nd thread/transaction have to wait for the first to commit?

[jezzer300]

This problem is now fixed. Wasn't to do with the above code!