NPE in Spring-JDBC with Oracle and SimpleJdbcInsert [SPR-16495]

[spring-projects-issues]

John Ahlroos opened SPR-16495 and commented

When running the following code:

// Inserts a row and returns the generated id
public String performInsert()
{
  SimpleJdbcInsert insert = new SimpleJdbcInsert(dataSource)
                .withTableName(LOG_TABLE_NAME)
                .withSchemaName(SCHEMA_NAME)
                .usingGeneratedKeyColumns(ID_COLUMN)
                .usingColumns(VALUE_COLUMN);
        KeyHolder keyHolder = insert.executeAndReturnKeyHolder(Collections.singletonMap(VALUE_COLUMN, json));
        String id = (String) keyHolder.getKeys().get(ID_COLUMN);
        return id;
}

This code will work with Spring JDBC 4.3.6.RELEASE but if I change it to 4.3.7.RELEASE or above it will fail in:

Caused by: java.lang.NullPointerException
	at org.springframework.jdbc.core.metadata.OracleTableMetaDataProvider.lookupDefaultSchema(OracleTableMetaDataProvider.java:79)
	at org.springframework.jdbc.core.metadata.OracleTableMetaDataProvider.<init>(OracleTableMetaDataProvider.java:68)
	at org.springframework.jdbc.core.metadata.TableMetaDataProviderFactory$1.processMetaData(TableMetaDataProviderFactory.java:74)
	at org.springframework.jdbc.support.JdbcUtils.extractDatabaseMetaData(JdbcUtils.java:336)
	at org.springframework.jdbc.core.metadata.TableMetaDataProviderFactory.createMetaDataProvider(TableMetaDataProviderFactory.java:64)
	at org.springframework.jdbc.core.metadata.TableMetaDataContext.processMetaData(TableMetaDataContext.java:206)
	at org.springframework.jdbc.core.simple.AbstractJdbcInsert.compileInternal(AbstractJdbcInsert.java:280)
	at org.springframework.jdbc.core.simple.AbstractJdbcInsert.compile(AbstractJdbcInsert.java:266)
	at org.springframework.jdbc.core.simple.AbstractJdbcInsert.checkCompiled(AbstractJdbcInsert.java:313)
	at org.springframework.jdbc.core.simple.AbstractJdbcInsert.doExecuteAndReturnKeyHolder(AbstractJdbcInsert.java:396)
	at org.springframework.jdbc.core.simple.SimpleJdbcInsert.executeAndReturnKeyHolder(SimpleJdbcInsert.java:142)

---

Affects: 4.3.14

Issue Links:

• SimpleJdbcCall can't access synonyms in Oracle database [SPR-16478] #21022 SimpleJdbcCall can't access synonyms in Oracle database
• Drop NativeJdbcExtractor mechanism in favor of java.sql.Connection.unwrap() [SPR-14670] #19234 Drop NativeJdbcExtractor mechanism in favor of java.sql.Connection.unwrap()

Referenced from: commits f2dc075, 766e602

Backported to: 4.3.15

[spring-projects-issues]

Juergen Hoeller commented

This turns out to be rather odd: The only reference that can be null add that point is the Connection returned from DatabaseMetaData.getConnection()... and I can't see any change in 4.3.7 that would have caused a regression here either. So we can be defensive against null there... but why is the metadata Connection not available in the first place?

[spring-projects-issues]

Juergen Hoeller commented

This seems to be a side effect of the #19234 refactoring: Instead of catching Exception as we did before, we changed it to SQLException... not covering an NPE anymore. Of course we never meant to cover an NPE in the first place, so by defensively checking whether the Connection is null there, we should be equally safe.

[spring-projects-issues]

John Ahlroos commented

Here is the difference in the implementations of lookupDefaultSchema().

In 4.3.6 we consume the NPE in an empty catch clause:

private void lookupDefaultSchema(DatabaseMetaData databaseMetaData) {
		try {
			CallableStatement cstmt = null;
			try {
				cstmt = databaseMetaData.getConnection().prepareCall("{? = call sys_context('USERENV', 'CURRENT_SCHEMA')}");
				cstmt.registerOutParameter(1, Types.VARCHAR);
				cstmt.execute();
				this.defaultSchema = cstmt.getString(1);
			}
			finally {
				if (cstmt != null) {
					cstmt.close();
				}
			}
		}
		catch (Exception ignore) {
		}
	}

While in 4.3.7 we only catch the SQLExceptions and let the NPE pass:

private void lookupDefaultSchema(DatabaseMetaData databaseMetaData) {
		try {
			CallableStatement cstmt = null;
			try {
				cstmt = databaseMetaData.getConnection().prepareCall(
						"{? = call sys_context('USERENV', 'CURRENT_SCHEMA')}");
				cstmt.registerOutParameter(1, Types.VARCHAR);
				cstmt.execute();
				this.defaultSchema = cstmt.getString(1);
			}
			finally {
				if (cstmt != null) {
					cstmt.close();
				}
			}
		}
		catch (SQLException ex) {
			logger.debug("Encountered exception during default schema lookup", ex);
		}
	}

That is most likely why it stopped working.

Why the connection is null from DatabaseMetaData I don't know, it seems to be the case for both versions. The implementation (SerialDatabaseMetaData) I get there is coming from Weblogic's client library (wlfullclient.jar) so it might be a bug there. Anyway, I think it might be a good idea to revert the Exception handling back as this method is only a lookup method that tries the guess the schema.

[spring-projects-issues]

Juergen Hoeller commented

We posted at almost the same time there, coming to the same conclusion :-)

Since we're generally trying to avoid accidental over-catching, I've added a not-null check for the Connection instead, logging a specific debug message in that case. A similar check applies to the initializeWithTableColumnMetaData implementation now when trying to include synonyms.