CODEWITHSUNDEEP
mysqllocking
eastwater
eastwater

Reputation: 5640

mysql select for update: not locked for read

Open 2 MySql command line consoles, and set autocommit=0.

console 1 (T1): select * from Employee where id=1 for update;

console 2 (T2): select * from Employee where id=1;
                the result displayed.   // should be locked

T2 should be locked when trying to select the employee. Right? It is select for upate.

console 2 (T2): update Employee set name ="FOO" where id=1;
                locked as expected

Upvotes: 0

Views: 66

Answers (1)

Charlie Dalsass
Charlie Dalsass

Reputation: 2014

No, you'd need to explicitly lock the read query using "LOCK IN SHARE MODE".

Otherwise, reads are not automatically locked in MySQL among separate connections. For more information see:

https://dev.mysql.com/doc/refman/5.7/en/innodb-locking-reads.html

In this document they provide an example where you can force locking - it is not default to lock.

Upvotes: 1

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