DB2 syntax (limit and dirty read) when running H2 (in DB2 mode)

Question

I have a few methods that I'm currently trying to unit tests. These methods is running fine (in production) against a DB2 v8 using Spring JdbcTemplates.

Each SQL allows "dirty reads" by appending "WITH UR" to the statement. Also, some of them uses "limit" by adding e.g. "FETCH FIRST 1 ROWS ONLY".

This works fine against a real DB2, but I want to unit test these methods against a in-memory database - this is where H2 enters.

Everything works fine if I remove "WITH UR" and the "FETCH FIRST..", but I don't want to change the methods, but simply change the backend database.

As far as I can see this isn't directly possible using H2, as the syntax is different (although I use MODE=DB2).

Now, what to do? Should/could I use another in-memory database? I do not want to change the methods nor add "test" features/hacks, so that's a no-go.

Ideas and likewise is much appreciated!

EDIT

I'm not sure if its me or what, but I get the following error. Notice, I'm using Spring 3.1 and H2 1.3.166 and the url for the database is "jdbc:h2:~/testdb;MODE=DB2". I have no idea why it fails, because the sql works when running in the H2 Console but not from my unit test (guess its not the H2 that is broken):

Tests run: 3, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.109 sec <<< FAILURE!
getAdvisor(impl.AdvisorServiceDaoImplTest)  Time elapsed: 0.078 sec  <<< ERROR!
org.springframework.jdbc.BadSqlGrammarException: PreparedStatementCallback; bad SQL grammar [SELECT * FROM ADVISOR FETCH FIRST 1 ROWS ONLY ]; nested exception is org.h2.jdbc.JdbcSQLException: Syntax error in SQL statement "SELECT * FROM ADVISOR FETCH[*] FIRST 1 ROWS ONLY "; SQL statement:
SELECT * FROM ADVISOR FETCH FIRST 1 ROWS ONLY  [42000-166]
    at org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator.doTranslate(SQLErrorCodeSQLExceptionTranslator.java:233)
    at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72)
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:603)
    at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:637)
    at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:662)
    at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:702)
    at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.queryForObject(NamedParameterJdbcTemplate.java:178)
    at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.queryForObject(NamedParameterJdbcTemplate.java:185)
    at impl.AdvisorServiceDaoImpl.getAdvisor(AdvisorServiceDaoImpl.java:150)
    at impl.AdvisorServiceDaoImplTest.getAdvisor(AdvisorServiceDaoImplTest.java:69)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
    at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:62)
    at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.executeTestSet(AbstractDirectoryTestSuite.java:140)
    at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.execute(AbstractDirectoryTestSuite.java:127)
    at org.apache.maven.surefire.Surefire.run(Surefire.java:177)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:338)
    at org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:997)
Caused by: org.h2.jdbc.JdbcSQLException: Syntax error in SQL statement "SELECT * FROM ADVISOR FETCH[*] FIRST 1 ROWS ONLY "; SQL statement:
SELECT * FROM ADVISOR FETCH FIRST 1 ROWS ONLY  [42000-166]
    at org.h2.message.DbException.getJdbcSQLException(DbException.java:329)
    at org.h2.message.DbException.get(DbException.java:169)
    at org.h2.message.DbException.get(DbException.java:146)
    at org.h2.message.DbException.getSyntaxError(DbException.java:181)
    at org.h2.command.Parser.getSyntaxError(Parser.java:484)
    at org.h2.command.Parser.prepareCommand(Parser.java:233)
    at org.h2.engine.Session.prepareLocal(Session.java:415)
    at org.h2.engine.Session.prepareCommand(Session.java:364)
    at org.h2.jdbc.JdbcConnection.prepareCommand(JdbcConnection.java:1111)
    at org.h2.jdbc.JdbcPreparedStatement.<init>(JdbcPreparedStatement.java:71)
    at org.h2.jdbc.JdbcConnection.prepareStatement(JdbcConnection.java:266)
    at org.springframework.jdbc.core.PreparedStatementCreatorFactory$PreparedStatementCreatorImpl.createPreparedStatement(PreparedStatementCreatorFactory.java:245)
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:581)
    ... 40 more

EDIT #2 In case anyone have the same problem here is what I found out. I was using the following:

<jdbc:embedded-database id="dataSource" type="H2">
    <jdbc:script location="classpath:sql/create_schemas.sql"/>
    <jdbc:script location="classpath:sql/create_tables.sql"/>
    <jdbc:script location="classpath:sql/create_test_data.sql"/>
</jdbc:embedded-database>

This means that Spring will re-instantiate the data source with a generic bean, thus my settings was lost. The solution (in my case) was to simply load the database programmatically with the following:

EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder();
EmbeddedDatabase db = builder.setName("salgdb").setType(EmbeddedDatabaseType.H2)
            .addScript("sql/create_schemas.sql")
            .addScript("sql/create_tables.sql")
            .addScript("sql/create_test_data.sql")
                .build();

Answer 1

What you could do is provide a patch for the H2 database, to support the "WITH UR" feature :-)

"FETCH FIRST 1 ROWS ONLY" already works with a recent version of H2, but only in the DB2 mode. To enable the DB2 mode, append ;MODE=DB2 to the database URL, as in:

jdbc:h2:~/data/test;mode=db2

Example:

create table customer(id int);
select * from customer fetch first 1 rows only;

I have tested this with H2 version 1.3.166, but it should also work in older versions, most likely 1.3.161 and newer. To test it outside of Spring:

• Download H2 from http://h2database.com
• Run the H2 Console tool
• Use the database URL: jdbc:h2:~/temp/testdb;MODE=DB2

• Run the statements:

  create table ADVISOR(id int);

  SELECT * FROM ADVISOR FETCH FIRST 1 ROWS ONLY;

I don't get an exception if I do this.

Answer 2

From version 1.3.175 H2 should support "WITH UR" too. H2 changelog