How to batch INSERT and UPDATE statements with Hibernate

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Introduction

JDBC has long been offering support for DML statement batching. By default, all statements are sent one after the other, each one in a separate network round-trip. Batching allows us to send multiple statements in one-shot, saving unnecessary socket stream flushing.

Hibernate hides the database statements behind a transactional write-behind abstraction layer. An intermediate layer allows us to hide the JDBC batching semantics from the persistence layer logic. This way, we can change the JDBC batching strategy without altering the data access code.

Configuring Hibernate to support JDBC batching is not as easy as it should be, so I’m going to explain everything you need to do in order to make it work.

Testing time

We’ll start with the following entity model:

PostComment Jdbc Batch

The Post has a one-to-many association with the Comment entity:

@OneToMany(
    cascade = CascadeType.ALL, 
    mappedBy = "post", 
    orphanRemoval = true)
private List<Comment> comments = new ArrayList<>();

Or test scenario issues both INSERT and UPDATE statements, so we can validate if JDBC batching is being used:

LOGGER.info("Test batch insert");
long startNanos = System.nanoTime();
doInTransaction(session -> {
    int batchSize = batchSize();
    for(int i = 0; i < itemsCount(); i++) {
        if(i % batchSize == 0 && i > 0) {
            session.flush();
            session.clear();
        }

        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);
    }
});

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
    ));

This test will persist a configurable number of Post entities, each one containing two Comments. For the sake of brevity, we are going to persist 3 Posts and the Dialect default batch size:

protected int itemsCount() {
    return 3;
}

protected int batchSize() {
    return Integer.valueOf(Dialect.DEFAULT_BATCH_SIZE);
}

Default batch support

Hibernate doesn’t implicitly employ JDBC batching and each INSERT and UPDATE statement is executed separately:

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]} 

Configuring hibernate.jdbc.batch_size

To enable JDBC batching, we have to configure the hibernate.jdbc.batch_size property:

A non-zero value enables use of JDBC2 batch updates by Hibernate (e.g. recommended values between 5 and 30)

We’ll set this property and rerun our test:

properties.put("hibernate.jdbc.batch_size", 
    String.valueOf(batchSize()));

This time, the Comment INSERT statements are batched, while the UPDATE statements are left untouched:

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]}

A JDBC batch can target one table only, so every new DML statement targeting a different table ends up the current batch and initiates a new one. Mixing different table statements is therefore undesirable when using SQL batch processing.

Ordering statements

Hibernate can sort INSERT and UPDATE statements using the following configuration options:

properties.put("hibernate.order_inserts", "true");
properties.put("hibernate.order_updates", "true");

While the Post and Comment INSERT statements are batched accordingly, the UPDATE statements are still executed separately:

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]} 

Adding version data batch support

There’s the hibernate.jdbc.batch_versioned_data configuration property we need to set, in order to enable UPDATE batching:

Set this property to true if your JDBC driver returns correct row counts from executeBatch(). It is usually safe to turn this option on. Hibernate will then use batched DML for automatically versioned data. Defaults to false.

We will rerun our test with this property set too:

properties.put("hibernate.jdbc.batch_versioned_data", "true");

Now both the INSERT and the UPDATE statements are properly batched:

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]} 

Benchmark

Now that we managed to configure Hibernate for JDBC batching, we can benchmark the performance gain of statement grouping.

  • the test case uses a PostgreSQL database installed on the same machine with the currently running JVM
  • a batch size of 50 was chosen and each test iteration increases the statement count by an order of magnitude
  • all durations are expressed in milliseconds

The results are:

Statement count No batch Insert duration No batch Update duration Batch Insert duration Batch Update duration
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

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Conclusion

The more rows we INSERT or UPDATE, the more we can benefit from JDBC batching. For write-most applications (e.g enterprise enterprise batch processors), we should definitely enable JDBC batching as the performance benefits might be staggering.

Code available on GitHub.

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6 Comments on “How to batch INSERT and UPDATE statements with Hibernate

    • The automatic batch insert does not work for IDENTITY columns. I works with batch updates and delete statements.

  1. Hi Vlad,

    I always enjoyed your blogs.
    I bought your book “High-Performance Java Persistence” and read thru few chapters. I have a problem and would like solve it efficiently. My postgres db table has multiple foreign keys and the resulting java entity has multiple JoinColumns (with @ManytoOne annotations and fetchType LAZY). How do I insert records in this table in a spring application using JPA? How do I check the foreign keys? Should I not check them before saving the entities? How do I get the errors when some foreign key constraint is violated while doing batch insert? Thanks.

    • The DB already checks the FKs. Being many-to-one associations, the parent ids will be passed from previous loading steps anyway.

      • The input list comes from a client application via rest API. It is possible some fk ids are incorrect. In case of batch insert, I like to continue inserting the good records and report back to the client the bad records (or some info about them). Is it possible?

      • If you fetch the entities in the initial phase of the batch import process, then the validation is done prior to writing the data.

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