[ 
https://forge.continuent.org/jira/browse/SEQUOIA-1150?page=comments#action_15563
 ] 

Emmanuel Cecchet commented on SEQUOIA-1150:
-------------------------------------------

Regarding the test file, note that the proper way to begin/commit transactions 
in Java is:
c.setAutocommit(false);
s.execute(...);
c.commit();

Sequoia automatically replaces s.execute("begin") and s.execute("commit") to 
the proper methods of the connection API.

> SELECT  ... FOR UPDATE with no actual UPDATE prevents backend recovery
> ----------------------------------------------------------------------
>
>          Key: SEQUOIA-1150
>          URL: https://forge.continuent.org/jira/browse/SEQUOIA-1150
>      Project: Sequoia
>         Type: Bug

>   Components: Recovery Log
>     Versions: sequoia 2.10.10
>  Environment: Discovered on Centos 5 with MySQL 5.1 for backends and 
> Controller
> Single controller configuration
>     Reporter: Joel Kozikowski
>     Assignee: Emmanuel Cecchet
>     Priority: Critical
>  Attachments: TestSequoiaSelectForUpdate.java
>
>
> If the following sequence is issued to the database:
> 1) Start transaction
> 2) SELECT * WHERE ID = 1234 FOR UPDATE
> 3) End transaction
> 4) <zero or more other queries>
> 5) Start transaction
> 6) SELECT * WHERE ID = 1234 FOR UPDATE
> 7) End transaction
> The following gets written to the recovery log:
> 1) BEGIN (transaction n)
> 2) SELECT * WHERE ID = 1234 FOR UPDATE (transaction n)
> 3) BEGIN (transaction n+1)
> 4) SELECT * WHERE ID = 1234 FOR UPDATE (transaction n+1)
> The absense of a "COMMIT" in the recovery log causes ""Lock wait timeout 
> exceeded; try restarting transaction"
>  in MySQL when played back (because two seprate transactions are trying to 
> lock the same record, but never release the locks).

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