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From "Vincent Cornet (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AMQ-3304) JDBCPersistenceAdapter lockDataSource property (and other settings) should appear on the SQLServer persistence page
Date Fri, 07 Dec 2012 13:31:21 GMT

    [ https://issues.apache.org/jira/browse/AMQ-3304?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13526378#comment-13526378
] 

Vincent Cornet commented on AMQ-3304:
-------------------------------------

A short page, like the one dedicated to SQLServer, could be enough.

First, maybe an example of datasource configuration:
{quote}
A dataSource targetting a Sybase ASE database can be configured as follows:
{code}
  <bean id="sybase-ds" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
 
    <!-- using jConnect -->
    <property name="driverClassName" value="com.sybase.jdbc4.jdbc.SybDriver"/>
    <property name="url" value="jdbc:sybase:Tds:localhost:4000/activemq"/>
    <!-- using JTDS -->
    <!-- <property name="driverClassName" value="net.sourceforge.jtds.jdbc.Driver"/>
-->
    <!-- <property name="url" value="jdbc:jtds:sybase://localhost:4000/activemq"/>
-->

    <property name="username" value="XXX" />
    <property name="password" value="YYY" />
    <!-- and so on with pool config -->
  </bean>
{code}{quote}

Then a paragraph about Sybase-specific behavior:
{quote}
When working on a given Sybase ASE database, each operation (e.g. statement execution) is
appended to the transaction log. This log grows over time, and space has to be freed in order
to let the server keep running.
ASE is able to free space up to the oldest opened transaction; that is, if you keep a transaction
open for too long, the transaction log only grows - until the allocated space is full and
the database goes down.
So when using the Master-Slave feature of ActiveMQ with a database lock on table ACTIVEMQ_LOCK
as synchronization monitor (see http://activemq.apache.org/jdbc-master-slave.html), you have
to be careful. If you use only one dataSource, hence only one database, then the lock mechanism
shall keep a transaction indefinitely open, and while messages are persisted the transaction
log shall grow until you run out of space.

It is therefore strongly advised to use a dedicated database for this lock: just define another
dataSource targetting a minimal database holding no data (only the ACTIVEMQ_LOCK table) and
use it as a lockDataSource in your configuration.
Example:
{code}
        <persistenceAdapter>
            <jdbcPersistenceAdapter dataSource="#sybase-ds" lockDataSource="#another-sybase-ds"/>
        </persistenceAdapter>
{code}
{quote}

                
> JDBCPersistenceAdapter lockDataSource property (and other settings) should appear on
the SQLServer persistence page
> -------------------------------------------------------------------------------------------------------------------
>
>                 Key: AMQ-3304
>                 URL: https://issues.apache.org/jira/browse/AMQ-3304
>             Project: ActiveMQ
>          Issue Type: Improvement
>          Components: Documentation
>    Affects Versions: 5.5.0
>            Reporter: Arnaud BRAND
>            Priority: Minor
>
> When using the JDBCPersistenceAdapter with SQLServer the use of the lockDataSource property
is mandatory, or else the transaction log will fill up (wether the db is in simple or full
recovery mode doesn't change anything), and the broker will eventually crash.
> The page http://activemq.apache.org/sqlserver.html should clearly state that the lockDataSource
should be used and should point to another database.
> Additionnaly, this page could give another configuration tweak for SQLServer which results
in a sensible performance improvement when queues are quite full (>50000 messages in our
configuration):
> {code:xml}
> <statements>
>   <statements findNextMessagesStatement="SELECT TOP 5 ID, MSG FROM ACTIVEMQ_MSGS 
WHERE CONTAINER=? AND ID > ? ORDER BY ID"/>
> </statements>
> {code} 

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