Build a Java App with CockroachDB and Hibernate

This tutorial shows you how build a simple Java application with CockroachDB and the Hibernate ORM.

We recommend using Java versions 8+ with CockroachDB.

For another use of Hibernate with CockroachDB, see our examples-orms repository.

Step 1. Start CockroachDB

Use CockroachDB Cloud

Choose your installation method

You can create a CockroachDB Basic cluster using either the CockroachDB Cloud Console, a web-based graphical user interface (GUI) tool, or ccloud, a command-line interface (CLI) tool.

Cloud Console (GUI)

Create a free cluster

Organizations without billing information on file can only create one CockroachDB Basic cluster.

1. If you haven’t already, sign up for a CockroachDB Cloud account.

2. Log in to your CockroachDB Cloud account.

3. On the Clusters page, click Create cluster.

4. On the Select a plan page, select Basic.

5. On the Cloud & Regions page, select a cloud provider (GCP or AWS) in the Cloud provider section.

6. In the Regions section, select a region for the cluster. Refer to for the regions where CockroachDB Basic clusters can be deployed. To create a multi-region cluster, click Add region and select additional regions.

7. Click Next: Capacity.

8. On the Capacity page, select Start for free. Click Next: Finalize.

9. On the Finalize page, click Create cluster.

   Your cluster will be created in a few seconds and the Create SQL user dialog will display.

Create a SQL user

The Create SQL user dialog allows you to create a new SQL user and password.

1. Enter a username in the SQL user field or use the one provided by default.

2. Click Generate & save password.

3. Copy the generated password and save it in a secure location.

4. Click Next.

   Currently, all new SQL users are created with admin privileges. For more information and to change the default settings, see .

Get the connection information

The Connect to cluster dialog shows information about how to connect to your cluster.

1. Select Parameters only from the Select option dropdown.
2. Copy the connection information for each parameter displayed and save it in a secure location.

ccloud CLI

Follow these steps to create a CockroachDB Basic cluster using the ccloud CLI tool.

The ccloud CLI tool is in Preview.

Install ccloud

Mac

You can install ccloud using either Homebrew or by downloading the binary.

Use Homebrew

1. Install Homebrew.

2. Install using the ccloud tap:

   brew install cockroachdb/tap/ccloud
   

Download the binary

In a terminal, enter the following command to download and extract the ccloud binary and add it to your PATH:

curl https://binaries.cockroachdb.com/ccloud/ccloud_darwin-amd64_.tar.gz | tar -xJ && cp -i ccloud /usr/local/bin/

Use the ARM 64 binary if you have an M-series Mac:

curl https://binaries.cockroachdb.com/ccloud/ccloud_darwin-arm64_.tar.gz | tar -xJ && cp -i ccloud /usr/local/bin/

Linux

In a terminal, enter the following command to download and extract the ccloud binary and add it to your PATH:

curl https://binaries.cockroachdb.com/ccloud/ccloud_linux-amd64_.tar.gz | tar -xz && cp -i ccloud /usr/local/bin/

Windows

In a PowerShell window, enter the following command to download and extract the ccloud binary and add it to your PATH:

$ErrorActionPreference = "Stop"; [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $ProgressPreference = 'SilentlyContinue'; $null = New-Item -Type Directory -Force $env:appdata/ccloud; Invoke-WebRequest -Uri https://binaries.cockroachdb.com/ccloud/ccloud_windows-amd64_.zip -OutFile ccloud.zip; Expand-Archive -Force -Path ccloud.zip; Copy-Item -Force ccloud/ccloud.exe -Destination $env:appdata/ccloud; $Env:PATH += ";$env:appdata/ccloud"; # We recommend adding ";$env:appdata/ccloud" to the Path variable for your system environment. See https://docs.microsoft.com/powershell/module/microsoft.powershell.core/about/about_environment_variables#saving-changes-to-environment-variables for more information.

Run ccloud quickstart to create a new cluster, create a SQL user, and retrieve the connection string.

The easiest way of getting started with CockroachDB Cloud is to use ccloud quickstart. The ccloud quickstart command guides you through logging in to CockroachDB Cloud, creating a new CockroachDB Basic cluster, and connecting to the new cluster. Run ccloud quickstart and follow the instructions:

ccloud quickstart

The ccloud quickstart command will open a browser window to log you in to CockroachDB Cloud. If you are new to CockroachDB Cloud, you can register using one of the single sign-on (SSO) options, or create a new account using an email address.

The ccloud quickstart command will prompt you for the cluster name, cloud provider, and cloud provider region, then ask if you want to connect to the cluster. Each prompt has default values that you can select, or change if you want a different option.

Select General connection string, then copy the connection string displayed and save it in a secure location. The connection string is the line starting postgresql://.

? How would you like to connect? General connection string
Retrieving cluster info: succeeded
 Downloading cluster cert to /Users/maxroach/.postgresql/root.crt: succeeded
postgresql://maxroach:[e-mail]:26257/defaultdb?sslmode=verify-full&sslrootcert=%2FUsers%2Fmaxroach%2F.postgresql%2Froot.crt

Use a Local Cluster

1. If you haven’t already, .

2. Run the command:

   $ cockroach start-single-node --advertise-addr 'localhost' --insecure
   

   This starts an insecure, single-node cluster.

3. Take note of the following connection information in the SQL shell welcome text:

   CockroachDB node starting at 2021-08-30 17:25:30.06524 +0000 UTC (took 4.3s)
   build:               CCL v21.1.6 @ 2021/07/20 15:33:43 (go1.15.11)
   webui:               http://localhost:8080
   sql:                 postgresql://root@localhost:26257?sslmode=disable
   

   You’ll use the sql connection string to connect to the cluster later in this tutorial.

The --insecure flag used in this tutorial is intended for non-production testing only. To run CockroachDB in production, use a secure cluster instead.

Step 2. Get the sample code

Clone the example-app-java-hibernate repo to your machine:

git clone https://github.com/cockroachlabs/example-app-java-hibernate/

The version of the CockroachDB Hibernate dialect in hibernate.cfg.xml corresponds to a version of CockroachDB. For more information, see .

Step 3. Run the code

The sample code in this tutorial (Sample.java) uses Hibernate to map Java methods to SQL operations. The code performs the following operations, which roughly correspond to method calls in the Sample class:

1. Creates an accounts table as specified by the Account mapping class.
2. Inserts rows into the table with the addAccounts() method.
3. Transfers money from one account to another with the transferFunds() method.
4. Prints out account balances before and after the transfer with the getAccountBalance() method.

In addition, the code shows a pattern for automatically handling by wrapping transactions in a higher-order function named runTransaction(). It also includes a method for testing the retry handling logic (Sample.forceRetryLogic()), which will be run if you set the FORCE_RETRY variable to true.

It does all of the above using the practices we recommend for using Hibernate (and the underlying JDBC connection) with CockroachDB, which are listed in the Recommended Practices section below.

The contents of Sample.java:

package com.cockroachlabs;

public class Sample implements Serializable {

    private static final Random RAND = new Random();
    private static final boolean FORCE_RETRY = false;
    private static final String RETRY_SQL_STATE = "40001";
    private static final int MAX_ATTEMPT_COUNT = 6;

    private static Function<Session, BigDecimal> addAccounts() throws JDBCException {
        Function<Session, BigDecimal> f = s -> {
            BigDecimal rv = new BigDecimal(0);
            try {
                s.save(new Account(1, 1000));
                s.save(new Account(2, 250));
                s.save(new Account(3, 314159));
                rv = BigDecimal.valueOf(1);
                System.out.printf("APP: addAccounts() --> %.2f\n", rv);
            } catch (JDBCException e) {
                throw e;
            }
            return rv;
        };
        return f;
    }

    private static Function<Session, BigDecimal> transferFunds(long fromId, long toId, BigDecimal amount) throws JDBCException {
        Function<Session, BigDecimal> f = s -> {
            BigDecimal rv = new BigDecimal(0);
            try {
                Account fromAccount = (Account) s.get(Account.class, fromId);
                Account toAccount = (Account) s.get(Account.class, toId);
                if (!(amount.compareTo(fromAccount.getBalance()) > 0)) {
                    fromAccount.balance = fromAccount.balance.subtract(amount);
                    toAccount.balance = toAccount.balance.add(amount);
                    s.save(fromAccount);
                    s.save(toAccount);
                    rv = amount;
                    System.out.printf("APP: transferFunds(%d, %d, %.2f) --> %.2f\n", fromId, toId, amount, rv);
                }
            } catch (JDBCException e) {
                throw e;
            }
            return rv;
        };
        return f;
    }

    // Test our retry handling logic if FORCE_RETRY is true.  This
    // method is only used to test the retry logic.  It is not
    // intended for production code.
    private static Function<Session, BigDecimal> forceRetryLogic() throws JDBCException {
        Function<Session, BigDecimal> f = s -> {
            BigDecimal rv = new BigDecimal(-1);
            try {
                System.out.printf("APP: testRetryLogic: BEFORE EXCEPTION\n");
                s.createNativeQuery("SELECT crdb_internal.force_retry('1s')").executeUpdate();
            } catch (JDBCException e) {
                System.out.printf("APP: testRetryLogic: AFTER EXCEPTION\n");
                throw e;
            }
            return rv;
        };
        return f;
    }

    private static Function<Session, BigDecimal> getAccountBalance(long id) throws JDBCException {
        Function<Session, BigDecimal> f = s -> {
            BigDecimal balance;
            try {
                Account account = s.get(Account.class, id);
                balance = account.getBalance();
                System.out.printf("APP: getAccountBalance(%d) --> %.2f\n", id, balance);
            } catch (JDBCException e) {
                throw e;
            }
            return balance;
        };
        return f;
    }

    // Run SQL code in a way that automatically handles the
    // transaction retry logic so we don't have to duplicate it in
    // various places.
    private static BigDecimal runTransaction(Session session, Function<Session, BigDecimal> fn) {
        BigDecimal rv = new BigDecimal(0);
        int attemptCount = 0;

        while (attemptCount < MAX_ATTEMPT_COUNT) {
            attemptCount++;

            if (attemptCount > 1) {
                System.out.printf("APP: Entering retry loop again, iteration %d\n", attemptCount);
            }

            Transaction txn = session.beginTransaction();
            System.out.printf("APP: BEGIN;\n");

            if (attemptCount == MAX_ATTEMPT_COUNT) {
                String err = String.format("hit max of %s attempts, aborting", MAX_ATTEMPT_COUNT);
                throw new RuntimeException(err);
            }

            // This block is only used to test the retry logic.
            // It is not necessary in production code.  See also
            // the method 'testRetryLogic()'.
            if (FORCE_RETRY) {
                session.createNativeQuery("SELECT now()").list();
            }

            try {
                rv = fn.apply(session);
                if (!rv.equals(-1)) {
                    txn.commit();
                    System.out.printf("APP: COMMIT;\n");
                    break;
                }
            } catch (JDBCException e) {
                if (RETRY_SQL_STATE.equals(e.getSQLState())) {
                    // Since this is a transaction retry error, we
                    // roll back the transaction and sleep a little
                    // before trying again.  Each time through the
                    // loop we sleep for a little longer than the last
                    // time (A.K.A. exponential backoff).
                    System.out.printf("APP: retryable exception occurred:\n    sql state = [%s]\n    message = [%s]\n    retry counter = %s\n", e.getSQLState(), e.getMessage(), attemptCount);
                    System.out.printf("APP: ROLLBACK;\n");
                    txn.rollback();
                    int sleepMillis = (int) (Math.pow(2, attemptCount) * 100) + RAND.nextInt(100);
                    System.out.printf("APP: Hit 40001 transaction retry error, sleeping %s milliseconds\n", sleepMillis);
                    try {
                        Thread.sleep(sleepMillis);
                    } catch (InterruptedException ignored) {
                        // no-op
                    }
                    rv = BigDecimal.valueOf(-1);
                } else {
                    throw e;
                }
            }
        }
        return rv;
    }

    public static void main(String[] args) {
        // Create a SessionFactory based on our hibernate.cfg.xml configuration
        // file, which defines how to connect to the database.
        SessionFactory sessionFactory
                = new Configuration()
                        .configure("hibernate.cfg.xml")
                        .addAnnotatedClass(Account.class)
                        .buildSessionFactory();

        try (Session session = sessionFactory.openSession()) {
            long fromAccountId = 1;
            long toAccountId = 2;
            BigDecimal transferAmount = BigDecimal.valueOf(100);

            if (FORCE_RETRY) {
                System.out.printf("APP: About to test retry logic in 'runTransaction'\n");
                runTransaction(session, forceRetryLogic());
            } else {

                runTransaction(session, addAccounts());
                BigDecimal fromBalance = runTransaction(session, getAccountBalance(fromAccountId));
                BigDecimal toBalance = runTransaction(session, getAccountBalance(toAccountId));
                if (!fromBalance.equals(-1) && !toBalance.equals(-1)) {
                    // Success!
                    System.out.printf("APP: getAccountBalance(%d) --> %.2f\n", fromAccountId, fromBalance);
                    System.out.printf("APP: getAccountBalance(%d) --> %.2f\n", toAccountId, toBalance);
                }

                // Transfer $100 from account 1 to account 2
                BigDecimal transferResult = runTransaction(session, transferFunds(fromAccountId, toAccountId, transferAmount));
                if (!transferResult.equals(-1)) {
                    // Success!
                    System.out.printf("APP: transferFunds(%d, %d, %.2f) --> %.2f \n", fromAccountId, toAccountId, transferAmount, transferResult);

                    BigDecimal fromBalanceAfter = runTransaction(session, getAccountBalance(fromAccountId));
                    BigDecimal toBalanceAfter = runTransaction(session, getAccountBalance(toAccountId));
                    if (!fromBalanceAfter.equals(-1) && !toBalanceAfter.equals(-1)) {
                        // Success!
                        System.out.printf("APP: getAccountBalance(%d) --> %.2f\n", fromAccountId, fromBalanceAfter);
                        System.out.printf("APP: getAccountBalance(%d) --> %.2f\n", toAccountId, toBalanceAfter);
                    }
                }
            }
        } finally {
            sessionFactory.close();
        }
    }
}

Update the connection configuration

Open src/main/resources/hibernate.cfg.xml, and set the hibernate.connection.url, hibernate.connection.username, and hibernate.connection.password properties, using the connection information that you obtained from the Cloud Console:

<property name="hibernate.connection.url">jdbc:postgresql://{host}:{port}/defaultdb?sslmode=verify-full</property
<property name="hibernate.connection.username">{username}</property
<property name="hibernate.connection.password">{password}</property

Run the code

Compile and run the code using gradlew, which will also download the dependencies:

$ cd example-app-java-hibernate

$ ./gradlew run

Toward the end of the output, you should see:

APP: BEGIN;
APP: addAccounts() --> 1.00
APP: COMMIT;
APP: BEGIN;
APP: getAccountBalance(1) --> 1000.00
APP: COMMIT;
APP: BEGIN;
APP: getAccountBalance(2) --> 250.00
APP: COMMIT;
APP: getAccountBalance(1) --> 1000.00
APP: getAccountBalance(2) --> 250.00
APP: BEGIN;
APP: transferFunds(1, 2, 100.00) --> 100.00
APP: COMMIT;
APP: transferFunds(1, 2, 100.00) --> 100.00
APP: BEGIN;
APP: getAccountBalance(1) --> 900.00
APP: COMMIT;
APP: BEGIN;
APP: getAccountBalance(2) --> 350.00
APP: COMMIT;
APP: getAccountBalance(1) --> 900.00
APP: getAccountBalance(2) --> 350.00

Recommended Practices

Generate PKCS8 keys for client authentication

You can pass the to to generate a key in PKCS#8 format, which is the standard key encoding format in Java. For example, if you have the user max:

$ cockroach cert create-client max --certs-dir=certs --ca-key=my-safe-directory/ca.key --also-generate-pkcs8-key

The generated PKCS8 key will be named client.max.key.pk8.

CockroachDB Cloud does not yet support certificate-based user authentication.

Use IMPORT INTO to read in large data sets

If you are trying to get a large data set into CockroachDB all at once (a bulk import), avoid writing client-side code altogether and use the statement instead. It is much faster and more efficient than making a series of and . It bypasses the altogether and writes directly to the of the database.

For more information about importing data from PostgreSQL, see .

For more information about importing data from MySQL, see .

Use reWriteBatchedInserts for increased speed

We strongly recommend setting reWriteBatchedInserts=true; we have seen 2-3x performance improvements with it enabled. From the JDBC connection parameters documentation:

This will change batch inserts from insert into foo (col1, col2, col3) values (1,2,3) into insert into foo (col1, col2, col3) values (1,2,3), (4,5,6) this provides 2-3x performance improvement

Retrieve large data sets in chunks using cursors

CockroachDB now supports the PostgreSQL wire-protocol cursors for implicit transactions and explicit transactions executed to completion. This means the PGJDBC driver can use this protocol to stream queries with large result sets. This is much faster than .

For instructions showing how to use cursors in your Java code, see Getting results based on a cursor from the PGJDBC documentation.

Note that interleaved execution (partial execution of multiple statements within the same connection and transaction) is not supported when Statement.setFetchSize() is used.

What’s next?

Read more about using the Hibernate ORM, or check out a more realistic implementation of Hibernate with CockroachDB in our examples-orms repository.

You might also be interested in the following pages:

• Client Connection Parameters
• Connection Pooling
• Data Replication
• CockroachDB Resilience
• Replication & Rebalancing