Vinay,
----- Original Message -----
From: ""Vinay"" <[EMAIL PROTECTED]>
Newsgroups: mailing.database.myodbc
Sent: Thursday, March 02, 2006 12:20 AM
Subject: Enforcing Isolation in MySQL database
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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.
you should use SELECT ... FOR UPDATE in this case. A normal plain SELECT in
InnoDB does not lock the rows it reads.
What should the application programmer to enforce database concurrency.
Thank you,
Vinay
Best regards,
Heikki
Oracle Corp./Innobase Oy
InnoDB - transactions, row level locking, and foreign keys for MySQL
InnoDB Hot Backup - a hot backup tool for InnoDB which also backs up MyISAM
tables
http://www.innodb.com/order.php
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