怎么可以上传自己做的网站,网络系统运维,团员团干部如何登录到系统,东营建设信息网公示介绍 JDBC长期以来一直为DML语句批处理提供支持。 默认情况下#xff0c;所有语句都一个接一个地发送#xff0c;每个语句都在单独的网络往返中发送。 批处理使我们能够一次性发送多个语句#xff0c;从而节省了不必要的套接字流刷新。 Hibernate将数据库语句隐藏在事务后写… 介绍 JDBC长期以来一直为DML语句批处理提供支持。 默认情况下所有语句都一个接一个地发送每个语句都在单独的网络往返中发送。 批处理使我们能够一次性发送多个语句从而节省了不必要的套接字流刷新。 Hibernate将数据库语句隐藏在事务后写抽象层的后面 。 中间层允许我们从持久层逻辑中隐藏JDBC批处理语义。 这样我们可以更改JDBC批处理策略而无需更改数据访问代码。 配置Hibernate来支持JDBC批处理并不是那么容易所以我将解释为使其工作所需要做的一切。 测试时间 我们将从以下实体模型开始 该帖子与Comment实体具有一对多关联 OneToMany(cascade CascadeType.ALL, mappedBy post, orphanRemoval true)
private ListComment comments new ArrayList(); 或者测试场景同时发出INSERT和UPDATE语句因此我们可以验证是否正在使用JDBC批处理 LOGGER.info(Test batch insert);
long startNanos System.nanoTime();
doInTransaction(session - {int batchSize batchSize();for(int i 0; i itemsCount(); i) {Post post new Post(String.format(Post no. %d, i));int j 0;post.addComment(new Comment(String.format(Post comment %d:%d, i, j)));post.addComment(new Comment(String.format(Post comment %d:%d, i, j)));session.persist(post);if(i % batchSize 0 i 0) {session.flush();session.clear();}}
});
LOGGER.info({}.testInsert took {} millis,getClass().getSimpleName(),TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNanos));LOGGER.info(Test batch update);
startNanos System.nanoTime();doInTransaction(session - {ListPost posts session.createQuery(select distinct p from Post p join fetch p.comments c).list();for(Post post : posts) {post.title Blog post.title;for(Comment comment : post.comments) {comment.review Blog comment.review;}}
});LOGGER.info({}.testUpdate took {} millis,getClass().getSimpleName(),TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNanos)); 该测试将保留可配置数量的Post实体每个实体包含两个Comment 。 为了简洁起见我们将保留3个帖子和方言的默认批处理大小 protected int itemsCount() {return 3;
}protected int batchSize() {return Integer.valueOf(Dialect.DEFAULT_BATCH_SIZE);
}默认批处理支持 Hibernate不会隐式使用JDBC批处理并且每个INSERT和UPDATE语句都是分别执行的 Query:{[insert into Post (title, version, id) values (?, ?, ?)][Post no. 0,0,1]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][1,Post comment 0:0,0,51]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][1,Post comment 0:1,0,52]}
Query:{[insert into Post (title, version, id) values (?, ?, ?)][Post no. 1,0,2]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][2,Post comment 1:0,0,53]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][2,Post comment 1:1,0,54]}
Query:{[insert into Post (title, version, id) values (?, ?, ?)][Post no. 2,0,3]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][3,Post comment 2:0,0,55]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][3,Post comment 2:1,0,56]}Query:{[update Post set title?, version? where id? and version?][Blog Post no. 1,1,2,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][2,Blog Post comment 1:0,1,53,0]}
Query:{[update Post set title?, version? where id? and version?][Blog Post no. 0,1,1,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][1,Blog Post comment 0:1,1,52,0]}
Query:{[update Post set title?, version? where id? and version?][Blog Post no. 2,1,3,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][3,Blog Post comment 2:0,1,55,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][3,Blog Post comment 2:1,1,56,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][1,Blog Post comment 0:0,1,51,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][2,Blog Post comment 1:1,1,54,0]}配置 要启用JDBC批处理我们必须配置hibernate.jdbc.batch_size属性 非零值允许Hibernate使用JDBC2批处理更新例如建议值介于5到30之间 我们将设置此属性并重新运行测试 properties.put(hibernate.jdbc.batch_size, String.valueOf(batchSize())); 这次批处理Comment INSERT语句而UPDATE语句保持不变 Query:{[insert into Post (title, version, id) values (?, ?, ?)][Post no. 0,0,1]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][1,Post comment 0:0,0,51]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][1,Post comment 0:1,0,52]}
Query:{[insert into Post (title, version, id) values (?, ?, ?)][Post no. 1,0,2]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][2,Post comment 1:0,0,53]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][2,Post comment 1:1,0,54]}
Query:{[insert into Post (title, version, id) values (?, ?, ?)][Post no. 2,0,3]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][3,Post comment 2:0,0,55]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][3,Post comment 2:1,0,56]}Query:{[update Post set title?, version? where id? and version?][Blog Post no. 1,1,2,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][2,Blog Post comment 1:0,1,53,0]}
Query:{[update Post set title?, version? where id? and version?][Blog Post no. 0,1,1,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][1,Blog Post comment 0:1,1,52,0]}
Query:{[update Post set title?, version? where id? and version?][Blog Post no. 2,1,3,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][3,Blog Post comment 2:0,1,55,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][3,Blog Post comment 2:1,1,56,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][1,Blog Post comment 0:0,1,51,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][2,Blog Post comment 1:1,1,54,0]} JDBC批处理只能针对一个表因此针对不同表的每个新DML语句都会终止当前的批处理并启动一个新的。 因此在使用SQL批处理时不希望混合使用不同的表语句。 订购说明 Hibernate可以使用以下配置选项对INSERT和UPDATE语句进行排序 properties.put(hibernate.order_inserts, true);
properties.put(hibernate.order_updates, true); 尽管对Post和Comment INSERT语句进行了相应的批处理但UPDATE语句仍单独执行 Query:{[insert into Post (title, version, id) values (?, ?, ?)][Post no. 0,0,1]} {[insert into Post (title, version, id) values (?, ?, ?)][Post no. 1,0,2]} {[insert into Post (title, version, id) values (?, ?, ?)][Post no. 2,0,3]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][1,Post comment 0:0,0,51]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][1,Post comment 0:1,0,52]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][2,Post comment 1:0,0,53]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][2,Post comment 1:1,0,54]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][3,Post comment 2:0,0,55]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][3,Post comment 2:1,0,56]}Query:{[update Comment set post_id?, review?, version? where id? and version?][1,Blog Post comment 0:0,1,51,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][1,Blog Post comment 0:1,1,52,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][2,Blog Post comment 1:0,1,53,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][2,Blog Post comment 1:1,1,54,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][3,Blog Post comment 2:0,1,55,0]}
Query:{[update Comment set post_id?, review?, version? where id? and version?][3,Blog Post comment 2:1,1,56,0]}
Query:{[update Post set title?, version? where id? and version?][Blog Post no. 0,1,1,0]}
Query:{[update Post set title?, version? where id? and version?][Blog Post no. 1,1,2,0]}
Query:{[update Post set title?, version? where id? and version?][Blog Post no. 2,1,3,0]}添加版本数据批处理支持 我们需要设置hibernate.jdbc.batch_versioned_data配置属性以启用UPDATE批处理 如果您的JDBC驱动程序从executeBatch返回正确的行数则将此属性设置为true。 通常可以安全地打开此选项。 然后Hibernate将使用批处理的DML来自动版本化数据。 默认为false。 我们也将使用此属性集重新运行测试 properties.put(hibernate.jdbc.batch_versioned_data, true); 现在 INSERT和UPDATE语句均已正确批处理 Query:{[insert into Post (title, version, id) values (?, ?, ?)][Post no. 0,0,1]} {[insert into Post (title, version, id) values (?, ?, ?)][Post no. 1,0,2]} {[insert into Post (title, version, id) values (?, ?, ?)][Post no. 2,0,3]}
Query:{[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][1,Post comment 0:0,0,51]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][1,Post comment 0:1,0,52]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][2,Post comment 1:0,0,53]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][2,Post comment 1:1,0,54]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][3,Post comment 2:0,0,55]} {[insert into Comment (post_id, review, version, id) values (?, ?, ?, ?)][3,Post comment 2:1,0,56]}Query:{[update Comment set post_id?, review?, version? where id? and version?][1,Blog Post comment 0:0,1,51,0]} {[update Comment set post_id?, review?, version? where id? and version?][1,Blog Post comment 0:1,1,52,0]} {[update Comment set post_id?, review?, version? where id? and version?][2,Blog Post comment 1:0,1,53,0]} {[update Comment set post_id?, review?, version? where id? and version?][2,Blog Post comment 1:1,1,54,0]} {[update Comment set post_id?, review?, version? where id? and version?][3,Blog Post comment 2:0,1,55,0]} {[update Comment set post_id?, review?, version? where id? and version?][3,Blog Post comment 2:1,1,56,0]}
Query:{[update Post set title?, version? where id? and version?][Blog Post no. 0,1,1,0]} {[update Post set title?, version? where id? and version?][Blog Post no. 1,1,2,0]} {[update Post set title?, version? where id? and version?][Blog Post no. 2,1,3,0]}基准测试 既然我们已经为JDBC批处理配置了Hibernate我们就可以对语句分组的性能提升进行基准测试。 测试用例使用与当前正在运行的JVM安装在同一台机器上的PostgreSQL数据库 选择了50的批量并且每次测试迭代都会将语句计数增加一个数量级 所有持续时间均以毫秒表示 报表数量 无批次插入持续时间 无批次更新持续时间 批量插入时间 批量更新持续时间 30 218 178 191 144 300 311 327 208 217 3000 1047 1089 556 478 30000 5889 6032 2640 2301 300000 51785 57869 16052 20954 我们执行INSERT或UPDATE的行越多从JDBC批处理中受益越多。 对于最写的应用程序例如企业级企业批处理程序 我们绝对应该启用JDBC批处理因为其性能优势可能是惊人的 。 代码可在GitHub上获得 。 翻译自: https://www.javacodegeeks.com/2015/03/how-to-batch-insert-and-update-statements-with-hibernate.html
