ActiveMQ中使用mysql做持久化报错：Cannot execute statement: impossible to write to binary log since BINLOG_FORM

ActiveMQ中如果使用mysql innodb的同时，开启了binlog，那么在ack消息的时候，日志里就可会报错：java.sql.SQLException: Cannot execute statement: binlogging impossible since BINLOG_FORMAT = STATEMENT and at least one table uses a storage engine limited to row-logging. InnoDB is limited to row-logging when transaction isolation level is READ COMMITTED or READ UNCOMMITTED.

这是因为，mysql默认的binlog_format是STATEMENT，而在READ COMMITTED或READ UNCOMMITTED隔离级别下，innodb只能使用的binlog_format是ROW。

而在ActiveMQ的store JDBC实现中（TransactionContext），为了提高并发性能，使用的是READ UNCOMMITTED：

     // a cheap dirty level that we can live with    
     private int transactionIsolation = Connection.TRANSACTION_READ_UNCOMMITTED;

所以，就会出现上面的问题。

解决办法有两个：

1、在mysql里设置binlog_format为ROW，此时binlog会增大，但是一般来说对数据复制支持的更好，建议单机高性能环境下使用。

2、在activemq.xml的jdbcPersistenceAdapter里配置transactionIsolation=“4”，即TRANSACTION_REPEATABLE_READ，此时事务更严格，会影响性能，建议在集群、强实时一致、不强调单机性能的情况下使用。

可以参见源码里的说明：

/**
     * set the Transaction isolation level to something other that TRANSACTION_READ_UNCOMMITTED
     * This allowable dirty isolation level may not be achievable in clustered DB environments
     * so a more restrictive and expensive option may be needed like TRANSACTION_REPEATABLE_READ
     * see isolation level constants in {@link java.sql.Connection}
     * @param transactionIsolation the isolation level to use
     */
    public void setTransactionIsolation(int transactionIsolation) {
        this.transactionIsolation = transactionIsolation;
    }