如何使用Hibernate批处理INSERT和UPDATE语句

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 List<Comment> 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 -> {
    List<Post> 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

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