从EJB计时器中删除大量行

从EJB计时器中删除大量行

您拥有的解决方案仍然会面临交易到期问题。

诀窍是在一个单独的事务中执行每个块，如下面的伪代码所示。

@Entity@NamedQueries ( value = {    @NamedQuery (        name = pagedDeleteExpiredItems        query=    DELETE FROM MyTable WHERe (<table key>) IN (     SELECt <table key> FROM (     SELECt ROWNUM AS row_num, <table key> FROM MyTable     WHERe timestamp <= :currentTime     )     WHERe row_num < :pageSize )    )})public class MyEntity {    @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)    int doPagedDeleteExpiredItems(Date currentTime, int pageSize) {        Query query = em.createNamedQuery("pagedDeleteExpiredItems");        query.setParameter("currentTime", currentTime);        query.setParameter("pageSize", pageSize);        int deleteCount = query.executeUpdate();        return deleteCount;    }}@EJBTimerpublic class DeleteExpiredItemsTimer {    @EJB(beanName = "MyEntity")    MyEntity myEntity;    @TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)    void handleTimeout(Timer timer) {        Date currentTime = getCurrentTime()        int pageSize = 100        int deleteCount;        do { myEntity.doPagedDeleteExpiredItems(currentTime, pageSize);        } while(deleteCount>0);    }}