Support HSQLDB Generated Keys Column Name Array In SimpleJdbcInsert

by ADMIN 68 views

Introduction

When working with databases, it's essential to understand how different drivers handle generated keys. In this article, we'll explore the limitations of HSQLDB's generated keys support and how it affects the usage of SimpleJdbcInsert in Spring Framework.

HSQLDB Generated Keys Support

The HSQLDB JDBC Driver, starting from version 2.0, supports the getGeneratedKeys method. However, this support is limited to returning the IDENTITY or GENERATED columns of the table. This means that if a primary key is generated through a different means, such as a trigger or a default value, it will not be returned using the getGeneratedKeys method.

SimpleJdbcInsert and HSQLDB

The SimpleJdbcInsert class in Spring Framework provides a convenient way to insert data into a table. However, when working with HSQLDB, it has some limitations. Specifically, when using the usingGeneratedKeyColumns method to specify the columns to retrieve as generated keys, HSQLDB will only return the IDENTITY or GENERATED columns of the table.

Example Use Case

Let's consider a simple table with a primary key generated through a default value:

CREATE TABLE DEMO(
  id UUID NOY NULL DEFAULT uuid(),
  val INTEGER VARCHAR(10) NOT NULL,
  PRIMARY KEY(id)
);

Using the SimpleJdbcInsert class to insert data into this table, we can specify the columns to retrieve as generated keys:

SimpleJdbcInsert jdbcInsert = new SimpleJdbcInsert(ds)
  .withTableName("DEMO")
  .usingColumns("val")
  .usingGeneratedKeyColumns("id");

KeyHolder keyHolder = jdbcInsert.executeAndReturnKeyHolder(Map.of("val", "foo"));
// keyHolder.getKeys() will be empty!

However, as we can see, the keyHolder.getKeys() method will return an empty result set. This is because HSQLDB only returns the IDENTITY or GENERATED columns of the table, and the primary key is generated through a default value.

Workaround

To retrieve the generated key, we can manually compile the SimpleJdbcInsert object and use the getJdbcTemplate method to execute the insert statement:

SimpleJdbcInsert jdbcInsert = new SimpleJdbcInsert(ds)
  .withTableName("DEMO")
  .usingColumns("val")
  .usingGeneratedKeyColumns("id");

// manually compile to help bypass
jdbcInsert.compile();

KeyHolder keyHolder = new GeneratedKeyHolder();

// ugly and shameless copy pasting of pieces of AbstractJdbcInsert just to prove a point
jdbcInsert.getJdbcTemplate().update(
  con -> {
    PreparedStatement ps = con.prepareStatement(jdbcInsert.getInsertString(), jdbcInsert.getGeneratedKeyNames());
    int[] insertTypes = jdbcInsert.getInsertTypes();
    StatementCreatorUtils.setParameterValue(ps, 1, insertTypes[0], "foo");
    return ps;
  },
  keyHolder);

// keyHolder.getKeys() will contain the uuid!

Conclusion

In conclusion, while HSQLDB supports the getGeneratedKeys method, it has some when working with SimpleJdbcInsert. Specifically, it will only return the IDENTITY or GENERATED columns of the table, and not the primary key generated through a default value. To retrieve the generated key, we can use a workaround by manually compiling the SimpleJdbcInsert object and using the getJdbcTemplate method to execute the insert statement.

Recommendations

  • When working with HSQLDB, use the getGeneratedKeys method with caution, as it may not return the expected results.
  • Consider using a different database driver, such as PostgreSQL, which supports the getGeneratedKeys method more robustly.
  • When using SimpleJdbcInsert, manually compile the object and use the getJdbcTemplate method to execute the insert statement to retrieve the generated key.

Future Work

  • Investigate the possibility of adding support for HSQLDB's generated keys to SimpleJdbcInsert.
  • Consider adding a feature to SimpleJdbcInsert to allow users to specify the columns to retrieve as generated keys, even if they are not IDENTITY or GENERATED columns.

References

Q: What is the issue with HSQLDB's generated keys support?

A: The issue with HSQLDB's generated keys support is that it only returns the IDENTITY or GENERATED columns of the table, and not the primary key generated through a default value.

Q: Why does this matter?

A: This matters because if you're using SimpleJdbcInsert to insert data into a table with a primary key generated through a default value, you won't be able to retrieve the generated key using the getGeneratedKeys method.

Q: What is the workaround for this issue?

A: The workaround for this issue is to manually compile the SimpleJdbcInsert object and use the getJdbcTemplate method to execute the insert statement. This will allow you to retrieve the generated key.

Q: Is this a limitation of HSQLDB or a limitation of SimpleJdbcInsert?

A: This is a limitation of HSQLDB. While SimpleJdbcInsert is designed to work with various database drivers, HSQLDB's generated keys support is not as robust as other drivers.

Q: Can I use a different database driver to avoid this issue?

A: Yes, you can use a different database driver, such as PostgreSQL, which supports the getGeneratedKeys method more robustly.

Q: What are the implications of using the workaround?

A: The implications of using the workaround are that you'll need to manually compile the SimpleJdbcInsert object and use the getJdbcTemplate method to execute the insert statement. This may add complexity to your code and make it harder to maintain.

Q: Is there a way to add support for HSQLDB's generated keys to SimpleJdbcInsert?

A: Yes, it's possible to add support for HSQLDB's generated keys to SimpleJdbcInsert. However, this would require modifying the SimpleJdbcInsert class to handle HSQLDB's generated keys support.

Q: What are the benefits of adding support for HSQLDB's generated keys to SimpleJdbcInsert?

A: The benefits of adding support for HSQLDB's generated keys to SimpleJdbcInsert would be that users would be able to use the getGeneratedKeys method with HSQLDB without having to use the workaround.

Q: Is there a plan to add support for HSQLDB's generated keys to SimpleJdbcInsert?

A: There is no plan to add support for HSQLDB's generated keys to SimpleJdbcInsert at this time. However, users can submit feature requests to the Spring Framework project to request this feature.

Q: What are the next steps for users who are experiencing this issue?

A: The next steps for users who are experiencing this issue are to either use the workaround or to consider using a different database driver that supports the getGeneratedKeys method more robustly.

Q: Can I contribute to the Spring Framework project to add support for HSQLDB's keys?

A: Yes, you can contribute to the Spring Framework project to add support for HSQLDB's generated keys. However, you'll need to follow the project's contribution guidelines and submit a pull request with your changes.

Q: Where can I find more information about this issue?

A: You can find more information about this issue in the Spring Framework documentation and in the HSQLDB JDBC Driver documentation.