MySQL - lock row for reading











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I am using socket.io server and multiple clients are making requests to this server. Server checks a MySQL innoDB table for data and if there is some data it updates its bit/column in table and send data to requested client.



But the problem is my multiple clients are occasionally getting same data.



Reason I feel is, 2 clients make requests to server exactly same point in time and both get same MySQL table row record before it was updated by other client.






mysql socket.io innodb







share|improve this question






















  • If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.
    – t.niese
    yesterday












  • Possible duplicate of Locking a row in a MYSQL table during a transaction
    – t.niese
    yesterday










  • How to properly use transactions and locks to ensure database integrity?
    – t.niese
    yesterday










  • @t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.
    – Irfan DANISH
    yesterday










  • If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.
    – t.niese
    23 hours ago

















up vote
1
down vote

favorite












I am using socket.io server and multiple clients are making requests to this server. Server checks a MySQL innoDB table for data and if there is some data it updates its bit/column in table and send data to requested client.



But the problem is my multiple clients are occasionally getting same data.



Reason I feel is, 2 clients make requests to server exactly same point in time and both get same MySQL table row record before it was updated by other client.






mysql socket.io innodb







share|improve this question






















  • If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.
    – t.niese
    yesterday












  • Possible duplicate of Locking a row in a MYSQL table during a transaction
    – t.niese
    yesterday










  • How to properly use transactions and locks to ensure database integrity?
    – t.niese
    yesterday










  • @t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.
    – Irfan DANISH
    yesterday










  • If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.
    – t.niese
    23 hours ago















up vote
1
down vote

favorite









up vote
1
down vote

favorite











I am using socket.io server and multiple clients are making requests to this server. Server checks a MySQL innoDB table for data and if there is some data it updates its bit/column in table and send data to requested client.



But the problem is my multiple clients are occasionally getting same data.



Reason I feel is, 2 clients make requests to server exactly same point in time and both get same MySQL table row record before it was updated by other client.






mysql socket.io innodb







share|improve this question













I am using socket.io server and multiple clients are making requests to this server. Server checks a MySQL innoDB table for data and if there is some data it updates its bit/column in table and send data to requested client.



But the problem is my multiple clients are occasionally getting same data.



Reason I feel is, 2 clients make requests to server exactly same point in time and both get same MySQL table row record before it was updated by other client.






mysql socket.io innodb




mysql socket.io innodb






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked yesterday









Irfan DANISH

4,77783054




4,77783054












  • If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.
    – t.niese
    yesterday












  • Possible duplicate of Locking a row in a MYSQL table during a transaction
    – t.niese
    yesterday










  • How to properly use transactions and locks to ensure database integrity?
    – t.niese
    yesterday










  • @t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.
    – Irfan DANISH
    yesterday










  • If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.
    – t.niese
    23 hours ago




















  • If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.
    – t.niese
    yesterday












  • Possible duplicate of Locking a row in a MYSQL table during a transaction
    – t.niese
    yesterday










  • How to properly use transactions and locks to ensure database integrity?
    – t.niese
    yesterday










  • @t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.
    – Irfan DANISH
    yesterday










  • If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.
    – t.niese
    23 hours ago


















If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.
– t.niese
yesterday






If you use the received data in follow-up select, insert or update then you have to use FOR UPDATE or FOR SHARE within the transaction.
– t.niese
yesterday














Possible duplicate of Locking a row in a MYSQL table during a transaction
– t.niese
yesterday




Possible duplicate of Locking a row in a MYSQL table during a transaction
– t.niese
yesterday












How to properly use transactions and locks to ensure database integrity?
– t.niese
yesterday




How to properly use transactions and locks to ensure database integrity?
– t.niese
yesterday












@t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.
– Irfan DANISH
yesterday




@t.niese - the link you shared is something different. Those locking doesn't lock a row for reading. I want to lock read, means the row my one connection is processing should not be read by other connection.
– Irfan DANISH
yesterday












If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.
– t.niese
23 hours ago






If you use FOR UPDATE then Other transactions are blocked from updating those rows, from doing SELECT ... FOR SHARE, or from reading the data in certain transaction isolation levels.. So if your isolation level is set up correctly then you can't have two transactions having a SELECT .. FOR UPDATE on the same row. So either the second transaction fails, or waits until the first FOR UPDATE finished.
– t.niese
23 hours ago



















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