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Horst Scheruga wrote:
If I use the transaction isolation level of READ-COMMITTED,
I have the problems that I do not see changes to the table made
within another connection (and commited) until I call commit in my
connection.
As of my understanding this behaviour is correct for the REPEATABLE-READ
and SERIALIZABLE isolation level, but not for READ-COMMITTED.
Beside the fact that this is not the behaviour I expect,
this results in performance loss, because lots of version have to be
created if multiple users have open connections.
I tried this under Windows 2000 [Version 5.00.2195] SP 3.
(The variables and status are attached to this mail)
Thanks in advance!
Best regards
Horst Scheruga
Show variables:
Variable_name Value
[snip]
version 4.0.4-beta-max-nt
[snip]
The InnoDB storage engine shipped with MySQL-4.0.4 does not support the
READ_COMMITED isolation level, it maps it to REPEATABLE_READ. The InnoDB
storage engine that comes with MySQL-4.0.6 does support READ_COMMITTED.
The particular isolation levels that InnoDB supports, and the details of
their implementation can be found in the InnoDB manual at:
http://www.innodb.com/ibman.html
If you're using READ_COMMITTED for speed purposes, I would re-think
that, as InnoDB tables using REPEATABLE_READ are as fast or faster than
most other databases READ_COMMITTED isolation levels. For example, the
e-week benchmark where MySQL with InnoDB performed as well as Oracle,
and better than SQL Server, Sybase and DB2 was run at REPEATABLE_READ,
while every other database ran at READ_COMMITTED.
-Mark
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__ ___ ___ __
/ |/ /_ __/ __/ __ \/ / Mark Matthews [EMAIL PROTECTED]
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, Full-Time Developer - JDBC/Java
/_/ /_/\_, /___/\___\_\___/ Flossmoor (Chicago), IL USA
___/ www.mysql.com
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