From: Vinay
Date: March 1 2006 10:31pm
Subject: Enforcing Isolation in MySQL database
List-Archive: http://lists.mysql.com/mysql/195329
Message-Id: <003e01c63d7f$f14527e0$157a40c0@vinay>
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----- Original Message -----=20
From: Vinay=20
To: mysql@stripped=20
Sent: Wednesday, March 01, 2006 5:00 PM
Subject: Enforcing Isolation in MySQL database


Hello ,
          I suppose the InnoDB tables in Mysql have REPEATABLE-READ as =
the default isolation. Is the concurrency enforced automatically by the =
database or is there anything=20
the application programmer has to do to make sure the data consistent.


How does the REPEATABLE-READ resolve the following scenario.


User1 opens a application and reads a row on the screen.
User2 opens the same application and read the same row on the screen.


User2 updates a field (and commits ,as the autocommit is on),
User1 still is reading the non-updated row , and updates the same field =
updated by the User2 to different value.


How does  it affect the database when normal select , update queries are =
used.


What should the application programmer to enforce database concurrency.


Thank you,
Vinay


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